OK. Time to get serious.
Photos and further details.
The first photo
is the heat exchanger which also passes the engine exhaust. 90 degree exhaust elbows come off the block and bolt to the bottom of the heat exchanger. An internal passage
sends the exhaust out the pipe on the end to the mixer elbow where the raw water
is injected and passes out the exhaust hose.
In the photo
the original elbow where I was able to remove the rusted pipe is on top, the spare which I cut off leaving some pipe is on the bottom.
So I see a couple of options.
1. Attach the spare elbow with pipe to the pipe coming out of the exchanger. This is the easiest and cheapest but is it "good enough"? In this situation, for me good enough would be a reliable fix that will give me min 4-5 years service
. The pipe on the elbow is very solid with very little loss of material to rust or corrosion
as is the pipe out of the exchanger for the first several inches.
2. Get the pipe out of the exchanger and go with all new pipe. This would be doable but will require cutting the pipe off flush and cutting it out of the female hole in the exchanger in pieces.
There's another issue. The engine is mounted with a V-drive and facing backwards in the boat. This means the front of the block (aft in the boat) is higher than the rear of the block (fore in the boat). The exhaust pipe comes out of the block front side and has a slight rise (see the drawing). This means that any residual water in the elbow runs down to the block and can wreck havoc. A friend with a sistership just had to replace his engine because the elbow corroded out and water drain back into the manifold and severely rusted the head
and exhaust valve in the first cylinder.
So while I'm doing all this I would also like to somehow make angle the pipe down so the water runs the right way. But I can't angle it down too much due to clearance issues.
Now I'm thinking a new pipe with a bend in it? What about welding the two together using an angled sleeve?
Definitely not trying to cheap
out but don't want to get too insane with a 30 year old engine. I do have access to a machine shop but not MIG or TIG.
Thanks all !!