I have a 1996 Four Winns with a 3.0 OMC Cobra. When the engine is revved up the U-shaped hose between the engine water pump and the thermostat housing swells up. I recently blew one of these hoses that was not very old. Any ideas???? I have disconnected the exhaust manifold, changed the thermostat, and checked the water pump. Now I am stumped.

Any help or ideas would be appreciated.

Thanks

Is a restriction somewhere. Typically a clogged manifold and/or riser is root cause.

Is it salt water boat? How old is the manifold and riser?

This is a freshwater boat. I disconnected the hose to the manifold and it did the same thing

Check your thermostat gasket , sounds like u put the wrong one on , the square end should be straight threw so water can go to your manifolds, if it isn't cut it out and use some permatex