I.D.C.E.

I'm working on my dad's 03 Formula 312 fastech, he has twin 6.2s. On a trip he had one of the engines cooling hoses from the raw water pickup to the tstat swell and get hit by the belt and of course showered the engine compartment. He replaced the hose and it immediately swelled again. He looked everything over and actually found rust stuck in the water exit area past the riser/elbow. The elbows were rusted however the mani and riser is ok, so he replaced all 4 elbows. He now ripped through all the hoses to make sure all is clear but the pipe keeps swelling while running with just the ear muffs/garden hose water source.

I'm going over there tomorrow morning to go over everything again. I'm not sure what else could cause pressure to that hose. The tstats were also replaced and are in good condition. Any help or input would be appreciated because it may point me in the right direction or trigger an idea lol. Thanks in advance!

Expensive Date

I am assuming that its not running hot because you did not say so.This is weird because there is not a lot of pressure in the water system.How is the flow coming out of the exhaust?I am figuring you have both transom and prop exhaust.
Do you have the dry gasket risers or the old style?Because thats were I am going I think the riser is clogged.Or and I hate to ask but are the thermostats in backwards.

If you have the new style dry gasket risers I have one with about 10 hrs on it to try.You are right down the road from me.

Griff

Sounds like the excess intake water is not bypassing to the exhaust like it should.
I would bet that the internal bypasses in the TStat housings are plugged up.
The sea pump keeps pumping water in, but its not bypassing enough to through the Tstat housing and exhaust. Something is definately plugged somewhere.

I.D.C.E.

Thanks for the input guys. Its fixed found debris in distribution ball clogging pressure relief hoses to manifold.