Over Heating

[alldodge]

Dam rain stopped me from looking into this over heating situation this morning but this is what i got last night. The two hoses that go from the thermostat housing to the back of the exhaust manifold get blistering hot while all other hoses stay cool. I took the plate off the front of the exhaust manifold expecting to see it plugged with rust but it was very clean. I wanted to run the engine with the plates off the front of the manifold to confirm I was getting a good flow of hot water from the front of the manifold but I did not get a chance to do this. Assuming the exhaust manifolds are good where would the next likely place to have a clog? The diagram shows the water flow going back to the thermostat form the manifold but cant tell where it gose after that. My guess would be the exhaust elbows on the back of the manifold. If the elbows are the problem where would the pee hole be that lets the water out of the elbow and into the exhaust flow?

Thanks

Water comes into the thermostat housing in the middle section. It leaves there and goes into the circulating water pump and is mixed with water coming from the exhaust manifolds. The circulating water pump moves the water into the engine and exits to the rear hoses going to the exhaust manifolds. With the water being really hot for those hoses, water isn't moving through the manifolds back to the thermostat housing.

In the bottom section of the thermostat housing there is a small hole which lets air out so the engine will completely fill with water. Your right after everything is filled the water will then pass up to the top section of the thermostat housing then out to the elbows. So the hoses getting hot going to the rear of the thermostat housing and the ones going back to the housing are not, there is a clog between the manifold and the elbow or on out to the prop.


Pull the hose going to the thermostat housing from the manifolds and see what kind of flow you get

 

[scatgo]

Had some time to work on the boat today. I had to take of the exhaust manifolds off to get the elbows off. The manifolds do have rust in them and the elbows have heavy rust. Water did flow out the pee hole in the elbows but maybe not enough. One of the three water passages in one of the manifolds where it meets the elbow was 100% clogged with something. I am going to clean all the rust out and see if that helps. Didn't see any flaps in the Y pipe. Can I run the engine with the exhaust manifolds off to see if it still overheats?