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Mercruiser 5.0 cooling hose swelling into serpentine belt

I did not open the engine compartment to look because I was driving. It looked so clean underneath that I never thought twice.
 
There was more water when I pulled the plug than I would like to see but he also hosed the boat down before I got there to look at it. Looking at the flow diagram it seems odd that water is pulled through that hose to water pump should not build pressure. I hope the extra pressure is not an exhaust leak into cooling water.
 
Just found this in another thread from someone with same issue:

Your issue is in the bypass tee located under the thermostat housing. Remove the oetiker clamps and take a look. Guaranteed to have an impeller blade in it blocking the flow. Causing excessive block pressure. Your circ pump hose is more than likely also swelling with rpm’s.
 
One may not be related to the other.

You have no idea when this issue started and the replacement of the impeller and housing may not have revealed a broken blade if they didnt look.

It would seem to me its time to remove all possible locations a chunk of rubber could be stuck.

So far most have been saying the water output is the likely issue.

Your find says it may be an water blockage input issue.

Time for more process of elimination...
 
MrJanx said:
There was more water when I pulled the plug than I would like to see but he also hosed the boat down before I got there to look at it. Looking at the flow diagram it seems odd that water is pulled through that hose to water pump should not build pressure. I hope the extra pressure is not an exhaust leak into cooling water.
Click to expand...
You gotta remember, water doesn't compress....if you restrict the outlet, the pressure will build...look at the numbers from the recent river run - I think the story is pretty consistent.
 
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