Saturday, February 11, 2012

If its not one thing...

So this weekend seemed to be an ideal time to do the annual mechanical maintenance tasks:
  1. Change the oil in the engine
  2. Change the oil and filter in the generator
  3. Replace the zinc on the engine heat exchanger.
  4. Take a look at the diodes in the alternator (I think one may be blown)
    So,  since it takes a long time to suck the oil out of the engine, I thought I'd get that started and it could be going on while I did one of the other tasks.  Step one for sucking the oil out of the engine is to warm up the engine so the oil thins out enough to make it go a little faster.

    RRRrrrrrr, vroom.  And then always check the exhaust for water.  This part of the task has become perfunctory, since the water is always there.  Well, not so much.  I'm glad I checked - the exhaust was dry.

    Already the day is not turning out like I had planned.  Rats.  OK, so add one more task to the list, and it goes on top:
    • Find/fix the problem with raw water cooling.
    The first thing I did was pull the cover off of the raw water pump (piece of cake, now that I have a SpeedSeal cover) and look things over.  All looked normal.  But perhaps the metal core of the impeller has come loose from the rubber part -  so put in a new impeller and try again.

    No joy - exhaust is still dry.

    That's where I am right now.  I'm drinking a beer and eating lunch.  Stay with me today as I work my way thru the raw water cooling system...  because this too is part of living aboard.



    Lunch is over, and the inspirational beer is consumed.

    I know I have water as far as the pump.  Next in line is the heat exchanger, and lookie there, item #3 on the original list is to change the zinc on the heat exchanger.  Doing so will remove an item from the list, and also allow me to determine whether water is getting this far.

    Yup, the zinc needed replaced, and yup, water gets to the heat exchanger.

    Downstream from the heat exchanger, the water next enters the water-cooled exhaust manifold, thru this connection:

    Is there any chance that the inlet is limed over?  I'd say there is, but whether or not it is, it sure looks like a gasket needs to be replaced here, so that will be the next stop in our journey.  There is more than an even chance that those bolts holding on the endplate will twist off instead of unscrewing.  If that happens, then I must remove the entire exhaust manifold and take it to the shop where I can drill out the bolt ends and probably rethread the holes.

    (Starting from the other end, I should also add that I can hear the engine exhaust coming out of the vented loop vent that is the next item downstream from the heat exchanger.  This means, I believe, that the exhaust elbow is not blocked.)

    But before I tackle removal of that endplate, I should remove the alternator that is visible in the picture below it.  Draining salt water thru the alternator won't do it any good, and the alternator is item #4 on the list anyway.

    So, that's what I'll do with the rest of the day - pull the alternator and check the diodes as well as the internal connections, since I still have evidence that the sense lead is not delivering current to the alternator internals somehow.

    And I'll spray WD-40 on those bolts.

    So, the original plan for the day got seriously changed.  Paraphrasing (and generalizing) von Moltke, "No plan survives contact with reality."
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    5 comments:

    Rado said...

    Curious what would happen if you started all the way at the other end of the exhaust - maybe something plugged the outlet fitting by means of say, laying an egg. Bolts twisting off are always a treat, my alternator mount did that to me in December, thankfully there was a more robust mounting kit that allowed me to completely bypass it. Researching seized bolt removal techniques, I saw people were recommending using penetrating oil and not WD-40. What shop are you using that's near Shilshole?

    bob said...

    Hi Rado -

    I can hear exhaust coming from the vent in the vented loop, so I know the hole in the exhaust elbow is not limed over.

    That gasket needs attention in any case, tho, doesn't it?

    Penetrating oil is indeed slightly better than WD-40. But it is WD-40 that I have. I should probably get some penetrating oil, shouldn't I?

    (And it's my shop :) )

    bob

    Anonymous said...

    Hi Bob: I get a kick out of reading your posts. Often full of good information with just a hint of humor. Before you attempt to remove those bolts try heating the manifold and tapping the heads of the bolts to knock some of the corrotion loose. But then being as mechanicaly inclined as you are you already know this. However I am surprised you have been ignoring your cooling impeller and cooling system. Using a good system flush chemical like Marsolve will keep the system free of scale and rust accumulation. Like flushing you car radiator. It removes a lot of the issues cause by salt water cooling. See you on the water.

    Anonymous said...

    Jack Tar

    Me said...

    I'm in the exact same position. Went to change the oil. No water in the exhaust. Impeller looked just ok but not great. Replaced the impeller. In doing so found that the woodruff key in the pump shaft was somehow magically missing! While I await another in the mail I filed a temporary one down from a larger size found at Stone Way Hardware and tried the pump with a new impeller. Still no water in the exhaust. So now I'll spend tomorrow hunting down the problem elsewhere. Blah.

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