Exhaust manifold Volvo Penta

[Ironman162]

Hi everyone, as you know we are often alone trying to fix our boats as best we can.
This forum is great to share ideas and talk thing over with people who had similar experiences.

My boat has two Chev 350 V8 engines with Volvo Penta 290 stern drives and stainless exhaust manifolds made by Hi-Tek in Queenland.
It has raw seawater cooling.The stainless manifolds are just on 10 years old and they have done well
Unfortunately the elbows between the engine and the heat exchanger has started to corrode, crack and split. Inside the heat changer where it runs cold they are in perfect condition.

The dilemma is the temperature difference makes it expand and contract at different rates wearing out the stainless tubing. Even I'm surprised how stainless would corrode when running hot!

I've got a good TIG welder on board. Would it be worth repairing given they are extremely expensive or would it be to better to stoop to good old cast iron risers. With stainless manifolds there is no possibility of water getting into the engine whereas we all know the perils of cast iron gasket failure!

Before anyone bite off my head the stainless risers were there already when I bought the boat.

Any ideas are welcome and appreciated as I sit here rolling ideas around in my head.

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