first, the exhaust most likely cracked because of improper winterization. hope your motor isnt cracked too
Yeah, I did drain it and flushed with antifreeze but apparently the plugs can get clogged with rust.
the engine is a GM 4.3, same block and heads as found in a full size half ton truck or a S-10 or Mercruiser or Volvo....
so you can get manifolds for any 4.3 (Mercruiser, Volvo, OMC, etc) however they dont mate very well with the Y-pipe.
there was a complete yamaha 4.3 exhaust swap thread on iboats. do a search. lots of parts have to be swapped.
and no, yamaha was not around for more than a few years. they violated both Mercruiser and Volvo patents and got their hands slapped so...... you have no parts support.
Did not know that, thanks for the info. I've talked to three boat mechanics (one of them Yamaha) and none of them have even seen one of these engines! I was naive in thinking that bc it was Yamaha it would be good!
here are a few links
https://forums.iboats.com/forum/eng...765-plumbing-mercruiser-manifolds-on-a-yamaha
https://forums.iboats.com/forum/eng...aha-4-3-v6-exhaust-manifolds-and-engine-block