Perkins 4-236 Shop Manual

 

The Perkins 4-236 is one of those small diesel engines that seemingly got adopted for every use under the sun.  One of those uses was in boats, and Eolian has one.

Because I like to have documentation on Eolian's important bits, I wanted the shop manual for this engine, and thanks to the courtesy of Martyn Lancing of Lancing Marine in the UK, I now have one.

If you would like a copy, provide me with your email address via a comment or at the email address in the Contact page of this blog.  The shop manual is a PDF document and is 15 MB in size, so be certain that your email provider will handle a message that large.

Perkins 4-236 Shop Manual

Genset Summer

After doing all that work on the generator this spring, when we got back after a couple of weeks at anchor, I found this...

Yep - the seawater pump on the generator had failed.

Apparently the first to go was the seal - that's what keeps the seawater inside the pump and away from the bearings that support the shaft:

That's not supposed to be three different pieces...

In fact the seal was so far gone that it came out in three pieces.

And then, because Kohler didn't see fit to use sealed bearings, the seawater running past the failed seal got into the bearings.  High carbon steel does not do well with exposure to salt water...

Bearings no more...

But thankfully, I have the tools and a rebuild kit was just an eBay away for a nominal sum, so one more time into the bilges, and the pump was as good as new.  Actually better than new, because the rebuild kit came with stainless bolts to replace the brass (?!) phillips screws that had originally held the cover plate on.  I also replaced the single brass (again...) screw that held the pump cam in place with a stainless one.  That brass screw came out in three pieces...  I can just barely imagine what would have happened if the cam had come loose in there when the pump was running...

Better than new!

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Genset Summer

Closure

I have to give all 3 of you patient readers closure on the generator issues...

It's done.  Finished.

I filled the fresh water side with water/antifreeze mix, opened the seawater valve and started it.

There were two problems.  The first was apparent even before the engine fired - diesel mist was escaping from the exhaust elbow flange.  I had been gentle with the 8 mm dia bolts that hold it on, fearing that I could strip or break them.   Apparently I had been too gentle.  A little judicious torque applied to the bolts solved that problem.

Next, after a few minutes of running, the engine started to slow down in what all of us with diesel engines recognize as the dreaded 'air bubble' somewhere in the system.  I bled it again (and got out some more air) but that didn't solve the problem.  Apparently there was now a bubble between the injection pump and the injectors.  Finally I started it up and applied a load (the water heater) which caused lots of diesel to be injected into the cylinders.  That did it - the air was swept out, leaving behind a smooth running engine.

So, this may be the longest oil change on record...  I started the oil change on 3/23, and here we are at the first day of May.

Gratuitous picture showing the finished product, again

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Closure

Almost...

It's hard to remember after so much work on the generator, that the original intent was only to change the oil.

Done, nearly

Nevertheless, here we are.  I got everything reassembled, with only a couple of difficult spots.

The first relief was that reinstalling the fuel line to the pump went a lot easier than when the filter end was firmly attached (I made up the filter connection, and then installed the filter...).  Everything else went pretty much by the book.

Old vs. New

But the new exhaust elbow caused a little difficulty because the water connection was rotated counterclockwise a little (see the little block bolted to the head at the far left in the 'old' view - where the wires go).  As a consequence, it interfered with the cylinder head over-temperature sensor.  But that was remedied by installing the sensor to another threaded hole in the head only an inch below the original.

The biggest problem was the wiring to the head over-temp sensor and the exhaust elbow over-temp sensor.  At the head sensor, there were two wires in the terminal (the sensors are in parallel - either can shut the engine down).  When I was sliding the connector on, one of the wires pulled out of the terminal.  It turns out that these are unusual terminals (read: Sebo's doesn't stock them), so I had to spend nearly an hour laboriously un-crimping the terminal and then re-crimping it with both wires firmly attached.

Done!

But I ran out of time.  I have bled the fuel system, but I still need to bleed the seawater side and refill the fresh water side of the engine.  Then I need to run it and look for:

• Oil leaks
• Exhaust leaks
• Fresh water leaks
• Salt water leaks

Hopefully there won't be any of these, and I can finally pull the curtains closed on this year's annual genset oil change.


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Almost...

Recursive Maintenance Continues

Maintenance recursiveness continues.

Being unable to budge the stubs left from grinding off the bolt heads, the only remedy was to remove the exhaust manifold/cooler to provide access for more drastic treatment of the bolt remainders than I could bring to bear with it in situ.

But...  before removing the exhaust manifold/cooler I had to drain both the antifreeze treated fresh water and the seawater from it.  This posed a problem because the genset and the heat pump share a thru hull, strainer and feed line.  Because it is still too cool here to do without the heat pump, I needed to install a shutoff valve in the genset seawater feed.

Genset seawater feed shutoff valve

This had it's own set of problems, first of which was a trip up into town to get some fittings.  Of course.  Despite the fact that I have a huge number of fittings aboard, none of them were suitable.  Then shut down the heat pump, close the seacock, cut the hose and clean up the mess from the drainage.  Finally, install the valve.

Draining the manifold/cooler

Now it was possible to drain the manifold.  Because Yanmar provided both drain petcocks and even drain hoses on the 2GMF, this was a clean job. 

And finally, removal of the now empty manifold was quite straightforward.

It turned out that the bolt stub removal was also easy...  because I took the manifold to Gustav at EngineTec here in Anacortes (highly recommended by Jason, and now I can add my enthusiastic recommendation as well).  An hour after I had dropped it off, Gustav called me telling me it was ready for pickup.  I barely had time to finish a post removal celebratory beer!

All I lack for reassembly is the gasket that goes between the manifold and the engine - currently on order.

---

I lay the blame for this incident at the feet of Kohler, the genset manufacturer.  Kohler adapted the Yanmar 2GMF to power the generator.  When they did so, one of the changes they had to make (in addition to relocating the oil filter) was to reorient the exhaust elbow.  The Yanmar elbow points straight down - that would have interfered with the generator body.

Kohler tilted the elbow to the right

So Kohler cut the elbow pipe off the flange and rewelded it at an angle to clear the generator body.  So far, so good.

The problem was that they made a dog's breakfast of it.  When the pipe was rewelded to the flange, the flange warped, making a seal against the manifold completely impossible.  Rather than redoing the weld, perhaps on a fresh, heavier flange, Kohler sealed the 1/8" gap using JB Weld or something similar applied to the manifold, and then to make sure, they installed two gaskets.  This all became obvious when I was able to inspect the manifold, and when I removed the gaskets and exposed the JB Weld (or whatever) on the manifold flange.  This crappy jury rig held for a while... perhaps 400 engine hours.  And then the leakage started.

Yanmar: 1
Kohler:   0


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Recursive Maintenance Continues

Genset Stage Three

Heads ground off the bolts

As I mentioned previously, I intended to grind the heads off of the bolts.  I could not budge the two on the right with a wrench without risking twisting them off, and the two on the left had corroded to the point where their heads were just nubs.  The plan was to grind off the heads, remove the elbow, and then use ViceGrip pliers to grip the stubs and turn them out, if possible.  The only tool that I could get to bear on the bolts was a Dremel tool with a little 3/4" grinding head...  it took about an hour for each bolt.

It's off!

Amazingly, even with the bolt heads removed, I had to drive a screwdriver between the elbow and the exhaust manifold to free the elbow. Corrosion products completely filled up the space between the bolts and the holes in the elbow flange, bonding it tightly. This does not bode well for being able to remove the bolts...

The inner tube is loose

...And this tells part of the story. The inner pipe was loose and had been ejected part way down the hose that attaches to the exhaust elbow...

Warped flange

And this is the rest of the story: the near edge (the bottom) of the flange is significantly warped. Combined with the loose inner pipe (above), this meant that hot seawater would be leaking out of the bottom of the flange. That seawater was supposed to cascade down around the inner pipe and join the exhaust gases near the far end of the elbow. Instead it was right there at the warped flange.

New fuel pump installed

With the primary and time-limiting task out of the way and the old elbow shipped off to Ben at ExhaustElbow.com, I had more room to work and more time, so I installed the new fuel pump.

Shiny new exhaust elbow

Late breaking news: Ben has completed the new elbow and will be shipping it soon! Gotta get those bolt stubs out!

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Genset Stage Three

Genset Saga Continues

Well, there has been a little progress.

Kohler oil filter stand-in

I have removed the remote oil filter mount, the (rusted out) oil lines and the heavy iron casting that Kohler installed to replace the oil filter and provide attachment points for the oil lines.  Holy cow!  That was not trivial work.  The banjo fittings at the oil line ends used 25 mm bolts, and it was pretty much everything I could muster in the confined space to break them loose.

As another example of Salnick’s Law of Recursive Maintenance, it was not possible to actually separate the oil lines from the engine because they were behind the water feed line to the sea water pump.  Since I had then to drain and disconnect the pump, this provided a perfect opportunity to replace the pump impeller.  The old impeller looked like it was new.

And while the pump was out I got the oil lines out, tho even with the water fed line out of the way it was still a complex geometry problem to unthread the lines in the cramped operation space.

Oil filter in Yanmar factory location (oil lines still in place)

In order to ensure that I had no leaks, I installed a new filter, reconnected the sea water line and fired up the genset.  There were no leaks, oil or water!

Next on the agenda:

• Replace the corroded mess of a fuel lift pump
• Remove the exhaust elbow and send it to the fabricator who will make me a new one out of 316SS.  This will not be easy.  Two of the bolts that hold the elbow on are corroded to the point that the heads are just nubs.  And of course these are the ones that are nearly impossible to get at.  To add, I can’t budge the other two... without risk of snapping them off. 
  
  My next plan is to use a Dremel tool to tediously grind off the heads of the bolts, remove the elbow and then use vice grips to attempt to remove the remaining “studs”.  Two of the bolts go into thru-holes in a flange on the block, so the worst case scenario there would be that they get drilled out and replaced with bolts and nuts.  The other two, the hardest to get at (naturally), go into blind holes...

And so the saga continues...

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Genset Saga Continues

The Boaty Way of Things

As a normal part of pre-season maintenance, I change the oil in the generator.

No big deal, right?  Should take less than an hour.

Before I remove the oil via a suction tube shoved down the dipstick hole, I heat it up - this makes the process go much faster.  I heat it up by running the generator, naturally.  So I started the generator.

After a while, it shut itself down.  Not the slowly chugging of a fuel starvation issue, but sudden - like I had hit the kill switch.

I pulled up the floorboard and was rewarded with an oil-spattered view...  the generator had spat out all its oil and shut itself down on lack of oil pressure.  What a mess!  Thankfully there is a drip pan under the engine big enough to contain the entire oil charge...  and that's where it was.  The part not on the batteries, walls, floorboards, etc.

I had had this happen once before due to the failure of the oil filter gasket, so I presumed that was what had happened here.  Consequently, I purchased (dearly) a factory authorized oil filter, presuming that the aftermarket filter that I had installed last year was the culprit.  And installed it. and filled the generator with fresh oil (whew!  that was the original objective).

When I started it, I was greeted with a spray of clean oil, right in the face.

OK...  not the oil filter.

A close examination revealed that the leak was likely at the oil pipe...  "Oil pipe," you ask?  Yes.  Kohler, the manufacturer of the genset, used a Yanmar 2gmf diesel engine as a power source.  But the Yanmar design has the oil filter screwed into the block in a horizontal position.  This means that when it is removed, it dumps a cup of oil all over the place, and more particularly, it would dump it outside the drip pan under the engine.  Kohler's answer?  Relocate the oil filter to the other side of the engine where there is a tight spot where it could be mounted vertically, and over the drip pan.

The fuel pump is in that corrosion... somewhere...

But sadly, this location is exactly under the location where the exhaust elbow will drip, if it is failing (uh oh...).  Yeah.  And so add the fuel lift pump.

So far, it seems that I need to replace the feed pipe to the oil filter, the lift pump, and the exhaust elbow.  Here are the costs:

Item	Cost
Lift Pump	$86
Oil Pipe	$209
Exhaust Elbow	$767

Now I want to put this into perspective...  A fuel pump for a big block Chevrolet engine costs less than $20.  And $209 for a 12" piece of 1/4" steel tubing??  But HOLY COW!  The exhaust elbow is breathtakingly expensive for an 8" long fabricated mild steel item.  I would have to bet that if I just bought the parts to build this generator from scratch it would cost as much as the entire boat!

In the boaty way of things, the perforated oil pipe cannot be removed without disconnecting and draining the sea water feed to the generator.  And a BIG wrench.  So, since I will have the feed disconnected from the sea water pump, I might just as well change the impeller there too, right?  Add another $40 and a big hassle.  And this presumes that I can get it apart without stripping any screws...

So, the current status is this:

• I have a new fuel pump on order.  
• I have a water pump impeller on order.  
• I will order the oil feed pipe once I have everything apart and haven't (hopefully) broken anything else in the process.  I don't see any alternative to this yet.

And as for the exhaust elbow?  I have a query out there with an individual who will build me one out of 316 stainless for far less than the factory mild steel one...

Salnick's Law of Recursive Maintenance

Whatever you want to do, you have to do something else first...

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The Boaty Way of Things

A January to Remember

One down, one to go

January was quite the month!  In no particular order:

• Eolian's heat pump quit delivering heat.  It didn't take too long to determine why...  Tho the Freon pressure was acceptable when the compressor wasn't running, the suction side dropped to 0 psi when the compressor started.  We're nearly out of Freon!
  Clearly there is a leak, otherwise the Freon would still be in there.  The operative question is:  Is this a recent, big leak, or is this a long-term tiny leak?  The heat pump is about 5 years old, so I guess either is possible.
  I have ordered and have been delivered of a 5 lb container of the proper refrigerant, and a syringe full of leak-stop.  Now all I need is the opportunity to load those into the system.  But...
• Tho I am still recovering from the near-paralysis event I experienced late this summer, I had cataract surgery scheduled for January.  If you're not interested in this, skip ahead...
  A most interesting operation - takes about 15-20 minutes, and you are semi-conscious for the duration.  The room is darkened and you are staring into a bright light - you never really see the surgeon open your cornea, slide in an ultrasound probe that destroys your old lens and sucks out the pieces, and then slide in a new lens.  The anticipation is far worse than the operation.
  Here I am the day following - vision still a little cloudy and blurry - I was told to expect that.  But surprisingly, the view thru my new eye is quite different from my old one!  It is as if everything in my old eye is being viewed thru an amber/brownish filter.  Colors are much truer thru my new eye!  A huge and unanticipated advantage! 
  Other eye later in the month.  No more prescription sunglasses!  I can have Polaroid sunglasses!
• The heat exchanger in our gas furnace at our log cabin developed a leak - we could smell combustion products in the house when the wind blew.  It was under warranty, but the labor was going to be $1700.  Thankfully, the technician that confirmed the perforation of the heat exchanger assigned the cause to under-sized ductwork - ductwork that the technician's company had installed.  They agreed to eat the labor charges, as well as to modify the ductwork at their cost.  That was completed this week.
• Eolian's TV crapped out.  While we were watching it, it started to cycle thru red screen, blue screen, white screen, green screen, etc.  Nothing would break the cycle, including a last ditch bit of percussive maintenance.
  New TV ordered and installed last week.
• Tho it has less than 50,000 miles on it, the rebuilt engine that our Suburban's Previous Owner installed in it is obviously failing.  Aside from a defective valve lifter that randomly turns it into a 7-cylinder engine, it consumes a half a gallon of water for every tank of gasoline.  I have found and fixed all the leaks (there were many), but the water consumption continues.  I presume that the intake manifold is leaking into an intake runner (there's no water in the oil).  I have the receipts from the Previous Owner's engine - he got a Chevy long block for $1000 - that is an amazingly low price - apparently too low in fact.
  So the Suburban goes into the auto hospital for a new engine.  My son convinced me that I should save myself for working on the classics in the shop:  65 Mustang, 68 GTO, and the current project, 1959 Impala. So somebody else gets to wrangle this one.
• Oh, and I figured out how to make my Sailrite LSZ-1 sew successfully with Tenara thread...

And it's worth remembering, the month isn't over yet...

A January to Remember

Runaway Starter

Starter motors are not designed for continuous service - they are not provided with any cooling capabilities.  This is because the design expectation is that they will see only intermittent service.  They are high-current, high-power devices however, especially the ones that are expected to crank diesel high-compression engines.  Now hold that thought...

A recent discussion on The Retirement Project bears review here.  It seems that when TJ went to start his engine, the engine start push button stuck, leaving the starter motor running continuously after the diesel had started.  Because of the lack of cooling, a runaway starter motor is a serious problem - aside from destroying the starter, a fire could result.

I recall an incident where a young woman pulled into a gas station where I was refueling my car, and proceeded to fuel hers.  Her starter motor was running, after she shut down her engine (presumably it had been running since she started her car...).  Running, but running poorly - the heat buildup had caused the armature to swell and it was dragging on the field poles, creating more demand for electricity and even more heat.  I opened her hood and found the battery lead to be red hot, smoking, with all the insulation burned off.  Remember, this was at a gas station, where this car (and mine!) were actively taking on fuel.  I shut off the fuel feeds to both cars and then used a tire iron to break the red-hot wire (easy - copper is soft when it is red hot).  The cause?  Welded contacts in the starter solenoid.

One time when driving (I was 17 at the time) my father's 1959 Oldsmobile, the same thing happened to me.  Again, the tool of choice was a tire iron, and I used it to try to pry the battery connection off of the battery.  And failed.  Instead, the post and part of the battery plates came out of the top of the battery, complete with plenty of sparks and acid.  In retrospect, it is lucky I didn't get to experience a hydrogen explosion.  Again:  the cause was welded starter solenoid contacts.

I guess it is not surprising that this happens - these contacts carry prodigious current - 75 - 100 amps in a car engine and more for a diesel, and are connected to a very inductive load.  When they are asked to open, the magnetic field in the starter collapses, boosting the voltage at the contacts, keeping the current flowing for an instant even tho the contacts are open: an arc occurs.  Most of the time, the contacts continue to open, extinguishing the arc.  But if the contacts are already damaged from arcing, the arc gets a head start because the contacts are already hot...

In TJ's case above, the cause was not welded contacts in the starter solenoid, but rather a stuck starter button.  But in my experience, this is much rarer than welded contacts in the starter solenoid.  Regardless of the cause however, the remedy to a runaway starter is the same:  Disconnect the battery.

Easier said than done.

All cars, and almost all boats have a hard-wired connection between the battery and the starter.  In boats, the usual case is that that "Off-1-Both-2" battery switch is only carrying the house loads - the starter is hard-wired.

I believe that this is a pretty serious safety hazard.

Blue Seas M-Series Mini Selector Battery Switch

Those big battery switches can easily carry the starter current load.  Even the smallest ones have tremendous current carrying capabilities. Here's a mini Blue Seas one:

• Cranking Rating: 10 sec. 1,500 Amps
• Intermittent Rating: 5 min. 500 Amps
• Continuous Rating: 300 Amps

For comparison, cranking Eolian's starter (Perkins 4-236 diesel) draws 200 amps - I know this because everything on Eolian goes thru the shunt for our Link2000 monitor. And everything also goes thru the battery switch on the power panel. Including the starter.  I can't take credit for this - Downeast (Eolian's manufacturer) built her this way.

If the starter on your boat does not go thru a battery switch (or THE battery switch), I'd sure try to find a way to make it so...

Runaway Starter

Expansion & Bubbles

Everything gets bigger when you heat it.  Fact of the universe.
Water is one of "everything", so when your engine warms up, the cooling water in it gets bigger - it expands.

In older cars, space was left at the top of the radiator for the water to expand into.  In newer cars, the radiator is filled to the brim, and there is an external expansion tank.  There is always one somewhere in the system - there has to be.

Expansion tank on Eolian's engine

It is no different for boat engines.  But.  No radiator, no expansion space in the radiator.  But there has to be an expansion space somewhere in the system.  Right?

OK, now second thought:  air bubbles.  Where do they collect?  Yup, you got it in one - at the highest point in the system, eventually.  In a car, we're back to that space in the radiator.  It's easy to replace the air bubbles in the system with more coolant if they collect in the expansion tank.  It's a good combination of uses.  And in any modern car, the expansion tank or exit to the external reservoir is at the highest point in the system.

Ah, but in a boat.  In a boat, the "radiator" (there isn't one - it's a heat exchanger instead) is unlikely to be the highest point in the system...  Do you have a water heater that gets its heat from engine cooling water?  I'll bet it is mounted considerably higher than the engine.  How about a Red Dot heater (Eolian has both)?  Same question.  So where do the inevitable air bubbles accumulate?

Well, at the highest point in the system.  Always.  On Eolian, that was the water heater.  So, guess how effective the heater was, given that the hot water coils were filled mostly with air?  Yeah, not so much.

Expansion tank, above the water heater

It's been years now, but I installed an auxiliary expansion tank/reservoir at the inlet for the engine cooling water at the water heater.  And collected a lot of air in it.  The expansion tank on the engine simply got filled completely with water - an ineffective and irrelevant (and now removed) bulge in the system.  I put a 14 lb radiator cap on the engine expansion tank, and moved the original 7 lb cap to the auxiliary expansion tank by the water heater.  That way the cap on the engine would never release, and the one on the auxiliary tank would.

Big change in water heater efficiency!

So where do the air bubbles in your engine cooling system accumulate?

Expansion & Bubbles

Only One Expansion Tank Now

(Part one of this story is here.)

Like with so many things,the preparation for this task far outweighed its actual execution.

Corroding cast aluminum expansion tank

There are only 4 bolts that hold the expansion tank on the engine, and they do not protrude into the water passage.  This means that they were not rusted or corroded - they were easily removed.  Loosening the hose clamp attaching the tank to the heat exchanger, and the tank was easily lifted out of position.  Far less work than I anticipated.

It's out!

...and the corrosion is worse than I knew

It turns out that the worst of the corrosion was at the hose attachment spud.  It was so bad here that I fear that I could knock off that spud with a sharp blow.  Good to get this failure point off the boat.

In an earlier post, I detailed the time and effort spent in trying to find a replacement fitting that would serve as a thermostat housing and provide a connection to the heat exchanger.  That search satisfied, I thought I was out of the woods.

Not so much.

Since I was in there, I know that my son would chide me if I did not replace the 40-year old thermostat.  So I started a search for a thermostat for a Perkins 4-236, 160°F.  Well it turns out that none of the diesel supply houses in Anacortes could provide one corresponding to the part number in my engine manual.  Or even in a cross-reference manual.

I thought that the thermostat looked very familiar. The one oddball thing was this little device:

Jiggle pin

I told you I did deep research...  In typically British fashion, it is called a "Jiggle Pin."  Its function is to allow air bubbles trapped below the thermostat to pass thru it when the engine is not running.  When there is water flow, the jiggle pin moves up and blocks the hole, stopping water from bypassing the thermostat.  A nice feature, but not strictly necessary, since once the thermostat opens, there is free passage for bubbles, which will then accumulate in the highest point in the cooling system.

I did find some Perkins thermostats.  In England.  For $50, not including shipping.

So I went to my local NAPA store.  I LOVE NAPA!!  No pimply-faced kid behind the counter that can't do anything without the computer (you should see their faces when I answer their question, "What kind of car is this from?" with "It's a Downeast 45 sailboat with a Perkins 4-236 diesel...  they are paralyzed) - experienced countermen who know engines.  I showed the thermostat to the counterman, and allowed as how it sure looked like one for a small block Chevy engine...  he went and got one off the shelf and with his calipers we compared the Perkins and Chevy thermostats.  Yup, the $8 Chevy thermostat is a drop-in replacement, tho without the (not strictly necessary) jiggle pin.

And then the second, and harder problem:  I needed a 1.5" hose that had one end expanded to 1.75" to fit over my new fitting.  And it had to have a right angle bend right past the expansion.  And a straight section at least 8" long to reach the heat exchanger.  Try searching for that on line!  The NAPA counterman took me into the hose room and gave me his calipers and left me to search.  It took me two minutes to find a suitable hose, a NAPA 8349.

What's left of the hose after I cut off the part I needed.  There are still a couple of useful bends there...

So, thanks to NAPA, in the space of 15 minutes I had solved both the thermostat and hose problems and was on my way back to the boat.  Can I say it again?  I LOVE NAPA!!

Done!

I ran the engine until it was hot, the thermostat opened, and the bubbles had accumulated in the expansion tank.  Job done!

Expansion tank, higher than the water heater

Only One Expansion Tank Now

Easter Egg Hunt

Perkins 4-236 Expansion Tank

Eolian has a diesel engine, a Perkins 4-236.   Because this is a marine installation, there is no radiator (instead there is a heat exchanger), and therefore no expansion space in the radiator.  For the marine installation, Perkins created a cast aluminum tank to provide the expansion space.

Tho the engine is still in its prime, the tank is failing (galvanic corrosion because it is in contact with steel?  Probably.)

One more lead-in:  An expansion tank should be the high point in the system, so that bubbles and air trapped in the system accumulate there.  But Eolian has an engine-heated water heater which is mounted above the engine, making it the high point in the system.  Long ago I added an after market expansion tank at the water heater engine cooling water inlet, so that we would not accumulate a big air bubble in the water heater, drastically reducing its heating capacity.  Eolian does not need the expansion tank on the engine.

So the fix to the failing expansion tank is simple, right?  Just remove the tank.

Not so fast.  The expansion tank traps the engine thermostat against the casting it is mounted to.  With the tank removed, we will need something else to hold the thermostat in place, and provide a connection for the 1.5" hose that carries the water from the engine to the heat exchanger.

My first thought was to contact our local diesel engine supply house, looking for a Perkins part to bolt on in place of the tank to do just that.  No luck.  Apparently Perkins made that special water outlet casting (which bolts onto the front of the head making a right angle turn upward and providing a four-bolt mounting for the thermostat and the tank), just for use with the expansion tank.  It seems that all other non-marine installations have only a two-bolt mounting pad for a standard water neck/radiator hose connection.

I considered just making a flat plate that gets bolted onto the platform to trap the thermostat, and then drilling it to accept a standard small block Chevy water neck.  I am still considering this option.

But wait...  What do you mean non-marine Perkins installations?  Where else are Perkins 4-236 engines used?  Very little research revealed that the Perkins 4-236 may have been the almost-universal industrial small diesel:

• Taxi cabs
• Fork lifts (Hyster)
• Towed air compressors
• Towed welders (Lincoln)
• Industrial tow vehicles, eg luggage tow trucks on runway ramps (Clark)
• Farm tractors (Massey)
• ... and more

Water outlet casting, thermostat, and water neck

For all these other installations, it turns out that Perkins made a whole host of water outlet casting and water neck combinations, with the resulting water flow directed to the left hand side of the engine, straight ahead, straight up, to the right, and several angles in between.

Wonderful!  A whole new universe of possibilities has opened up!

I contacted my brother-in-law back in Indiana (thanks Tom!) who is an antique tractor collector, and he provided me with several contacts for Massey tractor salvage yards, many of which provided additional contacts...  you know how this goes.  Almost everyone I talked to was very friendly and curious about my problem ("Did you say the engine is mounted in a boat??").  Finally, I found that Massey (tractors) part no. 37762701 would provide me with a water outlet facing forward, and to which I could (hopefully...) bolt a Chevrolet small block water neck.  This part is available new for a cost ranging from £19, $57, to $295 depending on where you look.

Massey 37762701

But I continued the search, this time starting with Lincoln welders, which also used the Perkins 4-236 engine.  In the way of the Internet, that led me hither and yon, but surprisingly, I ended up on a forum where boat owners with 4-236 engines were discussing using JBWeld to repair failing expansion tanks.  And one of the posters mentioned Trans Atlantic Diesels, and that they sold a number of parts that addressed exactly the problem of failing expansion tanks on Perkins diesels.  One of the solutions they sell is a combination expansion tank, exhaust manifold and heat exchanger, made by Bowman.  This was more than I wanted or needed (I've already replaced the heat exchanger with a Monel one, and replaced the exhaust manifold with a stainless steel one), but that forum poster also mentioned that supplied with this kit was a part that bolted directly onto the existing water outlet, trapping the thermostat and providing a hose outlet going to the right side of the engine...

Exactly!

Oh. My. Gosh.  This is exactly what I started out looking for originally!  So I called them.  You'll want to talk to Sheri Alexander - she is by far the most knowledgeable about Perkins engines, and in particular the marine versions, of anyone that I have talked to in this long journey.  Yup, they have such a thing!  But the one they sell with the Bowman  unit is designed for 2" hose, and my setup uses 1.5" hose...  Sherrie said they'd fabricate one for me with the 1.5" outlet for no additional charge!  And when I called back to provide the Perkins part number for my thermostat, she was already downstairs talking to the fabrication shop!

The Easter egg hunt is over.  The second part of the story, the actual removal of the expansion tank and installation of the new water neck/thermostat housing, is here.

Easter Egg Hunt

More Propeller Thoughts

Some time back I did a mind dump of some thinking about boat propellers.  And one of the comments on that post hit a nerve - one that I have been thinking about for years.

Tip vortices.  What are these?  They are the spiraling water that slips off the ends of the prop blades when it is turning.  They come from the fact that water on one side of the prop is at a higher pressure than water on the other side.  This arrangement holds just fine until you get to the end of the blade, and then the high pressure water just spills off the blade and joins the low pressure on the other side, making a vortex.  For visualization, the same thing happens at the ends of an airplane wing, causing sometimes beautiful effects.  And drag.

Wing Tip Vortices

Making vortices uses energy - energy that could have been used to propel water astern giving thrust.  So, how to stop this waste?  On an airplane wing (or a keel...), one way is to put up a fence to stop the spill-over, thus the development of winglets and winged keels.

So what would a fence on a propeller blade look like?

• Start with a conventional propeller.  
• Add a ring that goes all the way around the ends of the blades.  
• Extend the blades profile to meet the ring.  

This is an interesting example - the ring here is being touted as a guard, which of course it is.  But it almost meets the purpose of a fence.  It falls short only in that the ring is not wide enough to fully cover the ends of the prop blades.

Stationary ring bolted to engine

Why doesn't this prop guard achieve the purpose?  In fact, this is probably worse than no ring at all.  The tips will still be forming vortices, which will then immediately impact the (stationary) ring, creating additional turbulence and drag.    It is important that the tips extend to and attach to the ring, and that the ring rotates with the propeller.

Ducted fans have been using (stationary, however) rings forever.  And the cross section of the rings is designed to minimize flow turbulence as the fluid enters the duct (look at the leading edge of a jet engine cowling for an example).  If the rotating ring had such a cross section, drag could be reduced even further.

Now, if only I had a bronze foundry and some propeller tooling to play with...

If someone out there wants  to do the experiment, I need a RH 20x14 prop to fit a 1.25" shaft...

More Propeller Thoughts

Drip, Drip - Round 2

Junior version

Rats. Bought the wrong one. Anybody need a brand new filter bowl for a Racor 500FG?  (Mine are 900FGs, it turns out).

Now I gotta wait for shipping.  Again.

Drip, Drip - Round 2

Drip, drip

All last summer whenever we ran our generator, the smell of diesel wafted up from under the floorboards.  I looked in vain for a leak on the generator, and had even begun to suspect that there was a high-pressure leak downstream from the injection pump - that would produce a fine mist that might not accumulate and reveal itself.

But when I pulled up the floorboards recently, after not having run the generator for months I found some diesel down there on the floor.

The hunt began anew.

What I finally found was that Racor filter #1 was very slowly leaking diesel... and that it was dripping onto the exhaust hose from the generator.  This explained why the smell seemed to be associated with running the generator.

Examination of the Racor filter bowl showed diesel wetting the lower portion of the bowl.

Racor #1 (filter bowl nearly empty)

There are two penetrations of the bowl - one for the drain (black), and one for a water detection probe or a plug if the probe is not installed (we don't have the probe, so: the white plug):

Bowl penetrations

What to do?  Well, the very first step was to valve Racor #1 out of the fuel line and Racor #2 in instead.  Then I had to get the diesel out of the bowl.  Thankfully, there is enough room under the bowl drain to fit an empty oil bottle.  Draining filled nearly three of these, pausing to go outside and dump them back into the tank, before the bowl was empty.

Diesel drainage tool

I then  removed the bowl.  I removed the drain fitting and the plug and inspected the o-rings that seal each...  Couldn't see anything wrong.  But I cleaned everything up and reinstalled the fittings and then the bowl.

I've refilled the Racor and am waiting to see if the leak re-appears.

While I am waiting (this is a slooow leak), I spent some time online looking to see if I could purchase those o-rings.  No dice.  I could probably take the o-rings to somewhere like Tri-county Diesel and try to get some replacements (both of these o-rings are viton, not neoprene, which makes it a little harder).

But then I found that I could buy an entire new filter bowl, complete with the drain and plug fittings and o-rings for less than $10, so I ordered one (how could I not?).  If my re-making of the o-ring connections fails to stop the leak, I'll just install the new bowl and keep the old one as a spare (I'll replace the o-rings on the old bowl with equivalent neoprene ones).

Drip, drip

Six Hours

I don't know what's the matter with me.

I have changed Eolian's oil twenty times now.  Each time I have run the engine prior to the task... to warm up the stiff oil (down there in the bilge, the temperature could be near the water temperature, 48° right now).

But not this time.  See, I was going to change the oil filter with this oil change, and I decided not to run the engine before that.  Eolian's Perkins 4-236 has a horizontally mounted oil filter, and with a long period between engine runs, it partially drains back thru the oil passages.  I didn't want to have to deal with a full oil filter when removing it.

So I decided to pump out the oil with our vacuum can, without an engine run, when it was cold.

Wow, was that a bad decision.

It took six hours of pumping on the vacuum can to get the 8 quarts of oil out.  Yes, the oil filter change-out wasn't as messy...  but it was so not worth it.

Oh, and I have a vacuum leak in the can somewhere.  It wasn't enough to pull a vacuum and renew it when it was filled with oil.  No, I had to pretty much keep pumping, for six hours straight.

I'm so exhausted that I can barely lift this bottle of beer to my lips.

Six Hours

Random Propeller Thoughts

Eolian's low aspect ratio propeller

I've been thinking about propellers lately.  A lot.


No, I can't explain that.  Perhaps it is a residue of our recent election.  Or something.

Nevertheless...

Now, I am not a trained Naval Architect.  But still, I have thoughts which seem coherent (to me at least, but then the judge may be biased), some brought on by casual observation of a rooster tail following a heavy cruiser.  Even riding on a ferry you can see evidence of a jet of water that eventually surfaces astern.

To me, the whole idea of thinking of a propeller as a water screw is, well, screwed.

Imagine that the that theoretical speed of a boat which would be determined only by the pitch of the prop and its RPM is called S_t.  In the common parlance, "slippage" - that condition when the boat is moving at less than S_t, is considered to be an inefficiency.

But imagine that a boat is moving thru the water at exactly S_t...  there is zero "slippage" - the prop is a perfect screw.  But then the only force on the prop is drag, as it completes its revolutions thru the water.  So how then is any force created* to move the boat forward?

How about this instead:  Newton's Third  Law:  For every action there is an equal and opposite reaction.  Imagine now that the prop's mission in life is to throw as much water astern as it can...  in a sense the boat becomes a rocket, propelled by the water being thrown away aft.  This theory would have as a consequence that "slippage" is required for propulsion.  If the boat reaches S_t, from the boat's perspective NO water is being thrown aft... NO propulsion.  This also says that a boat will never reach S_t, because the closer it gets, the less propulsive force is available - a hydraulic version of Zeno's Paradox.

Given a fixed amount of horsepower applied to the shaft, the product of the amount of water discharged and its speed are fixed.  If you want more water discharged, then for a fixed amount of horsepower input, the discharge speed of the water must be decreased.  And vice versa.  So, if you want a high speed discharge jet (high S_t), you must compromise with less water in the jet.  Therefore, assuming the same Chevy V8 engine, installed in a high-speed racing hydrofoil, you'll need a comparatively small diameter prop with a HUGE pitch.  With that same engine in a tug, a large, slow-turning prop will give you humongous thrust, but with the compromise of a low top speed.  Variable pitch props do not solve the problem because they only allow their pitch to be changed, not their diameter.

What do you need for your boat?  I bet that you want the most speed you can get.  So:  the highest pitch prop that still provides sufficient thrust to get you somewhere near S_t for that pitch.  Still a guessing game, tho empirical formulae do exist.


*I said that at S_t there would be no thrust.  That is not (at least theoretically) true.  Since the beginning of flight, aircraft propeller blades have had an airfoil cross section.  That is, they are really rotating wings, not only generating thrust by virtue of their pitch, but also using the pressure differential the airfoil creates between the front of the prop blades and the rear: lift.  An aircraft propeller, even operating at (or above!) S_t still delivers thrust because of this.  It strikes me that there is a lot of room for hydrodynamic improvement in water propellers, specifically in improving their lift/drag ratios.  Aircraft wings and propellers (and sailboat keels!) long ago gave up the low aspect ratio shape that today's boat propellers still retain.  Continuing with that thought, boat propellers, it would seem to me, would be well served if they moved toward narrow high aspect ratio blades with a cross sectional shape derived from hydrofoils.  Another trade-off:  enough "meat" will need to be retained in those thin blades to handle the thrust forces...

Random Propeller Thoughts

Now we can go

You know, there is something kind of irritating about Facebook's "Your Memories" posts, well at least for me, this spring.  I've been getting suggested posts showing us out in the islands or otherwise off the dock, and yet, here we are, in the first week of May, still emulating a teak-lined apartment.

Well, that has changed, finally.  Two projects which have prevented the boat from moving are done.  First, the compass binnacle and pedestal have been reassembled, and the throttle and gear shift levers are once again connected.  Oh yeah, and everything is now spiffy-shiny.

Recursive project completed.

The second project took longer.  In fact, the compass binnacle was kind of a fill-in, since we were trapped at the dock and couldn't move anyway.  This project was the exhaust hose failure - a much more difficult project.  After removing the old hose, the next problem I ran into was that tho the engine exhaust elbow was 3" OD and the old hose (and thus the new hose) was 3" ID, the water lift muffler inlet was 2 7/8" OD.  Undoubtedly this was because the muffler was a custom construction and 2 1/2" schedule 10 stainless pipe was used to make the inlet...  that pipe is 2 7/8" OD, probably the closest to 3" they could get.  I discovered this when I went to clean off what I thought was just some of the inner liner of the old hose from the inlet.  Nope, it was some kind of rubber tape, wrapped around the inlet to fill the gap in diameters.  It was also apparent that this was not the first solution tried - there was evidence of water leakage at the inlet, probably caused by an attempt to just clamp the daylights out of a 3" hose and try to squeeze it down enough to make a seal.  Not.

I gave a lot of thought to this, how to match up the diameters.  Finally, I settled on the approach the last mechanic had used - it has lasted successfully for 19+ years, after all.  OK, so since the old rubber tape was gone, I needed a replacement.  

I bought a 36" length of 2" wide, 1/32" thick, adhesive-backed silicone rubber tape.  I chose the smaller thickness so that I could make two wraps around the pipe, minimizing a leakage path thru the joint at the ends of the tape.  I wanted adhesive-backed tape because the inlet is almost inaccessible, and the tape would have to stay in place while I fiddled with installing the hose.  And finally, I wanted silicone rubber because it has a much higher temperature tolerance (400°F +) than neoprene or buna N rubber.

Silicone rubber gap-filler tape installed

Then all that remained was to "just" install the hose.  Because it was the least accessible (and most fragile, I didn't want to mess up the silicone tape), I installed the muffler end first.  That part was easy, being pretty much a straight shot.  Everything got a good dollop of silicone rubber RTV too, just to seal any small gaps.  Then tighten down the two hose T-clamps to stabilize the joint.

Next the hard part:  wrestling the alligator - bending the hose and getting it onto the exhaust elbow.  The hose is only slightly more flexible than a 3" tree branch.  This part took blood, sweat, but thankfully no tears.  And then two more T-clamps and the job was done.

Alligator: wrestled.

I waited until the next morning in order to give the RTV time to cure and then started the engine. No leaks! Woo HOO!

So, by the time you read this, we will be out at anchor in the Islands somewhere.

Yeah!

Now we can go

Exhausted

Remember, a few posts ago when I went Uh oh...?

Well, the time finally came up.  I wedged myself into a small, wedge-shaped compartment right next to the refrigeration compressor (Turn it off!  And more importantly, remember to turn it back on...).

As my body slowly became more compliant with the wedge-shaped space, I had to, slowly, with only a couple of inches freedom of movement, saw out a section of the exhaust hose.

Why just a section?  Well, this stuff is about as flexible as a 3" diameter tree branch.  There is no way that I would be able to bend it enough to get one end off of its pipe while the other end is connected - it's only 18" long.  So I chose to cut out a section from the center, which would give me enough freedom of movement to deal with the two remaining ends.

Ugly, isn't it?

So, over the course of a few hours, I was able to make the two necessary saw cuts thru the heavy, multiple-wire reinforced rubber.  What came out, after I re-inflated my body to its normal shape, was pretty ugly.

Looking at the cut end that passed thru the external salt deposit (I cut it there on purpose), you can see that the thin outer layer of rubber is loose from the bulk of the hose.  And closer examination shows that that bulk rubber at that location is actually completely cooked - hard as a rock and fractured, barely hanging together.

How did this happen?  The exhaust gases are water cooled.  Well, this is the top of the hose, near the water lift muffler.  Nearly the worst possible location if the water flow was weak (by the time it got here, it would probably be just running along the bottom of the hose).  And there have been some occasions over the years where raw water flow thru the engine was reduced.  I think this is the eventual consequence, come back to haunt me a lot later.

This is the tool that I used to cut the hose.  It is a handle especially designed to take Sawz-all blades.  I have a metal cutting blade chucked in it for this job.  It is really the only tool that I could have used to make these cuts, given the space constraints.

For the removal of the two end pieces of hose, I pressed a Dremel tool into service, using a tiny cut-off wheel.  It sliced thru the rubber and the wires with ease.  I had originally been worried about cutting too deep, marring the sealing surface of the pipes, but that was unnecessary.  Those wires are so hard and springy that as each was severed, it opened up the cut more.  It was not necessary to cut the rubber beneath the wires - their tension tore it.

Now all I have to do is bend a piece of new hose enough to get it in the space, and over the pipes at each end.  Sounds easy right?  A story for another time...

Exhausted