OMC Cobra 5.0 Raisers overheating

[pdanielsson]

On a routine check of my newly rebuilt engine we noticed the the holes that the flappervalve pins are inserted in had been enlarged due to overheating of the raiser. Instead of beeing round they were now 1.5 inches long causing the flapper valves to malfunction. Luckily no enginge damage.<br />After replacing the raiser we noticed that it still gets extremely hot, however, the enginge runs perfect at 120F, I can even put my hands on the manifolds. I have not yet water tested the boat, can it be that using a garden hose attachment does not give the boat enough water to cool both enging an the raisers? If so this damage happened when I ran the boat on land while flushing the engine. I do start the boat every week if I don't use it in the lake.<br />Question: How come the raisers are running warmer than the engine?<br />The engine is 5.0 with Fuel injection.<br />Water pump is belt driven and made out of brass.<br />Engine has about 150h total time.

 

[pdanielsson]

Re: OMC Cobra 5.0 Raisers overheating

Correction:<br />The flapper valves are sitting in the Y-pipe and that is the part that gets extemely hot, to the point that the metal breaks down.<br /><br />Pd

 

[Don S]

Re: OMC Cobra 5.0 Raisers overheating

What year engine and drive?<br />Have you tried replacing the impeller? They are only good for a couple of seasons. (Don't go by engine hours on rubber goods, impellers, bellows & Such)<br />Even with great water pressure, the engine may stay cool on the hose, but the exhaust can be hot.<br />I doubt the metal is getting hot enough to break down, if the rubber hoses just above them are still ok.

 

[pdanielsson]

Re: OMC Cobra 5.0 Raisers overheating

It's a 1994 OMC Cobra 5.0<br />Everything is new, engine, raisers, y-pipe etc.<br />That's the strange thing, how come the y-pipe could get so hot and fail but the ruber hose above be intact?? I found the flapper valve when I took the outdrive off to replace the gimble bearing. I just found out that Volvo decided to take out the flapper valves in 1995, any comments on that?<br /><br />Pd<br />Orlando FL