Friday, July 6, 2012

Boat jewelry

Remember this little exercise with the exhaust manifold that happened this past spring?  Well now it has come full circle.

Boat Jewelry

A little internet research turned up Marine Exhaust Systems of Alabama.  Amazingly, they were able to fabricate a replacement exhaust manifold from heavy 316 stainless plate and deliver it to Seattle for about half the delivered cost of a cast iron one from Perkins.

So, what exactly is this exhaust manifold thing?  On an auto engine, the exhaust ports of the engine are connected to a cast iron manifold that collects the exhaust and conveys it to the muffler.  And on a car, that manifold runs almost red hot.  On a car, that is not a problem because of all the air flowing thru the engine compartment.  But on a boat, that is too much heat to safely have trapped below the floorboards.  So, marine engines have water-cooled exhaust manifolds.

There it is!
So, there is ours, lurking just below the intake manifold (the intake has the yellow warning sticker on it).  The cooling water inlet is on the right (hose clamp shining brightly), and the water discharge is the hose connection on the left.  The exhaust elbow, which conveys the exhaust to the water-lift muffler is also on the left, below the water discharge, but you can't see it in the picture.

Out with the old...

Last Friday, we stayed at the dock, and I tackled the task of pulling out the old cast iron manifold and replacing it with the beautiful new stainless one.  I won't bore you with the blow-by-blow details of wedging my body into the space and turning nuts that are not quite completely inaccessible.  Instead, you can just imagine me cursing the British engineers who designed things that way.  Repeatedly cursing.

And in with the new!
Now, there's always some trepidation when using non-factory parts, as to whether they will actually fit.  And right up to the point where I trial-fitted the new manifold, I had the fear that after going thru all the steps of disassembly, that I would have to reassemble with the old manifold because the new one didn't fit in some way.  And that was a real possibility, since the clearances are so tight.

I needn't have worried.  The new manifold slipped right into place, perfectly.  Kudos to Marine Exhaust of Alabama!

I inspected the old cast iron manifold; there is no evidence of water leakage into the exhaust gas side.  So, I guess it could have stayed in there, for a while yet.

But you know what?  I am going to sleep better.


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