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Mercruiser 57 overheating hot manifolds new manifolds and risers

davebowen

New member
"Hi
I`ll start at the beginin


"Hi
I`ll start at the begining as its always best !
Have a rinker 240 with the 5.7 engine, last year had problems with her overheating whenever I pulled onto the plane or pushed it at around 3000 rpm plus. As I`m on the thames it was not a major issue at the time but everyone said new manifolds and risers ( boat is 10 years old ) . I have spent the weekend fitting them only to find that the starboard manifold and riser is still getting hot where as the port as cold. I took her for a run for about 30 mins, not many places to open up but did do around 3000rpm to give her some work and altho it didn`t overheat the starboard manifold and riser was hot. I also notice the port pipe after the rubber pipe on the riser was also hot, but not the manifold !
Today I have checked the water flow, it seems ok however when I blew into the water feed pipe to the starboard manifold, there was some pressure and the water blew around and came out of the port side of the thermostat housing if that makes sense. The exhaust sounds slightly different as well altho that could be me !!
Any thoughts on where to start next ? Should there be so much back pressure in the exhaust ? Am I paniking over nothing ? is it normal for one side to be cold yet the other hot ?"
 
ou may need to remove and clea

ou may need to remove and clean them water feed pipes i dont think that back pressure is normal
 
"Thanks for that, spoke to som

"Thanks for that, spoke to someone today who said it may be just a blockage in the cow horn y pipe. Its below the water line so not easy to check. Am also going to change the engine water pump just to rule that out, altho it seems ok."
 
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