Hi Ralph
I went to the boat Saturday and removed some parts. I think I may have wasted my time removing these parts, and I’ll explain why.
First- I would have gone during the week but the marina said weekend only to avoid contact with the marina employees. A very few optimistic people there were removing winter covers. There were some boats in the water but I believe these are the marina owners boats and work boats. I got the emergency broadcast slap on the wrist at about 2pm but had almost finished my job by then.
Almost everything came out rather easily so I took home the entire exhaust and heat exchanger.
Almost, because the original hose from the injection elbow to the muffler was stuck on (looks like some kind of glue) and very difficult to remove so I had to destroy it. On hindsight I could have just unscrewed the muffler as I did in the end anyway and removed the whole manifold and muffler as a unit and saved me an hour of cursing and pain. I am too old to sit on the shaft log bent in three for an hour without suffering the next day, it’s like yoga if you never did yoga before.
That inside back 1/2 inch nut on the manifold was easy once I got the right combination of socket, short extension, and ratchet. I was lucky to have just the right combination because there is no other way to get a wrench on this nut unless you remove the intake “silencer”.
So all the the 14 stud nuts were easy to get off even though rusty. And so here’s the point - I may have wasted my time.
I get home and last night I start taking it all apart. There are 10 studs, 5 on either end of the manifold. Two of these on the front and four on the back hold on what the parts manual calls a “connector”, a hose nipple. Beneath these are three identical gaskets, then the manifold end cover which is a flat piece of steel, and then another gasket. Of course it’s these gaskets that are leaking, they are rather thick, appear to be some cheap rubbery paper material.
The 10 nuts on these gaskets were loose. I got home and they come off very easily so I thought how about if I tightened them? Those that I did not already loosen could go down a 1/2 to more than a full turn. Especially the 6 that hold on the three “connectors” and compress two of these gasket layers.
I have never touched these nuts before. My general rule is if it ain’t broke don’t fix it. But in this case I believe that if I tightened these nuts 12 years ago I would have avoided some problems. There was far less corrosion on the front and back of the engine back then. Also, in hindsight, had I known last week, I would have tightened these nuts and called it good for another season rather than go through this pain.
Also in hindsight, it would be very easy to remove this front plate and redo the gasket while it is still on the engine. I should have done this years ago. If you had new gaskets ready and already had drained the antifreeze for another reason, it would be a 30 minute job. I didn’t because I thought that big plug was holding the plate on but no, it holds nothing.
There is a design flaw in this part. There is no bolt compressing this gasket at the center just under the iron plug. You can see where the gasket was not squeezed well around this plug. In fact, when the plug started to rust, that rust might try to lift the steel plate because the plate fits tightly around the plug threads.
Back end
Front end
Inside front cover plate
This shows some pitting but not between the gasket and steel where the gasket was squeezed between the aluminum and steel plate. These pits in the steel are where there was no aluminum on the other side of the gasket. I think maybe this is an example of crevice corrosion? The surface of the aluminum looks perfect. Bottom left is where the leaking occurred.
The iron pipe nipple and plug in the aluminum extrusion are stuck, I am soaking these to try and loosen but am afraid to break the aluminum if I use too much force. There appears to be a lot of carbon inside the manifold. Big chunks about 1/4 inch thick have fallen out so maybe cleaning it out would be useful.
All the iron pipes and the injection elbow look in good condition but I am not sure if I can get them apart. Maybe I won’t. I am shocked at how heavy they are. I’m sure the guy who designed the nice light exhaust manifold did not expect someone to hang this much iron off the back of it.
Tom
26 C #28 North Star with a W13
Penetang
