Carver Owners Forum

Thank you guys so much for the help with the start/running issue

Torsson wrote:Source of the post The thermostat opens nice when boiled.

When boiled?? Do you know what temp it's supposed to open at and did you measure the water temp when it started opening?

You need to get the belt problem fixed first. Slippage there will definitely reduce the ability of the pump to push water. Are you just trying to replace the belt that's on there or are you looking up the actual belt for the motor? Those could be different due to a prior owner.

The *last* thing I'd think about would be the "internal" water pump. Those very rarely are the cause of engine overheats. Usually it's the raw water pump or some restriction on the inlet (clogged strainer or through-hull) or some restriction further downstream like a clogged oil cooler or heat exchanger.

What i have checked now
1. Thermostat starts open at 60 degrees celsius and is fully open before 70 so i can rule out the thermostat (The thermostat has 60 degrees celsius stamped on it).
2. Impeller looks good (Have orderd replacement but looks not like the issue).
3. The internal water pump seems works with the test i made. started the engine and att idle 600rpm or so i removed a coolant hose and hold my hand to make pressure and when i released the hand coolant came flowing, so it is at least not dead.

I will se if i can get the correct belts and not just something from the auto parts store.

The engine that gets to hot has hose from the internal waterpump to the water heater 3-4 meters away and then back to the thermostat house (Or other way) and when it started to get hot i think the water heater was running. Can the water heater somehow make/help the engine overheat?. Just a thought becaus last year i did not use the waterheater.

If you want to cross the water heater issue off the list.....run a short piece of hose from the inlet to outlet, effectively removing the heater from the circuit......if the water temp in the heater is high then it may not help a weak system that has a problem somewhere else....

The water heater could not overheat the engine, not in any practical way. The water heater should only get to about 140F max anyway, which would be normally cooler than what the engine runs.

If you have any doubt though and want to rule it out, you can bypass it as bud37 says.

I suspect you have some blockage in the raw water flow somewhere.

You can get the belts at most automotive stores, they just need to cross-reference to the correct size. The types of belts are the same.

Are you in salt water? If so, how old are the exhaust manifolds and elbows? Are the exhaust manifolds fresh water cooled (coolant) or raw water cooled? How hot are the elbows getting during an overheat?

Do you have a U shaped oil cooler on the front of the engine? If so, they are known to restrict easily from failed impellers in the past, disintegrated anodes, and marine growth.

km1125: I found the "original" belts for this engine and i will change both och both engines when they arrive. Then i think i can rule out the hot water at least .

Viper: The boat has been in fresh water since i bought it last summer before that it was in salt water since it came to sweden in 2006. When i have changed the belts i will take with me a temp gun and check the temps on next trip. No i have "Straight" oil cooler but i think the oil cooler is before the impeller what i can se Water intake->Hose goes somewhere under the kitchen and back in a u shape to oil cooler -> Seawater pump -> heat exchanger -> elbows etc. I think the manifolds are coolant cooled but not 100% sure.

The Seawater intake has a bowl shaped filter but looks like its not impossible for debre to go trough that and maby clogg the oil cooler. Will take with me someone that knows engines better than me when the belts arrive then i can make a full day and go trough everything suggested here.

(Did not think about the oil cooler because they where hidden under carpet covered "walkway" between the engines )

Other thing i was thinking the hours on the engines are somewhere 1100h but in the documentation this boat had Mercruser 5.7L Bluewater from 1988 and now the boat has 2 5.7L 350 Crusaders now so if the hours are correct or not i have no clue. What kind of hours is a good indication to get someone to rebuild and check everything?.

Before you go too far with all these things, make sure the thru hull valve (where the water is pulled in)....is not plugged/restricted...make sure it is full open.....

Did not have notification on email when i got answers. Had a hard time to get belts that would fit. but then i remember i have a company account at a Hydraulic & belt store. Took a rope, mesured it got a belt that fitted perfect and after that the overheating stopped. But after a few weeks one engine did not start again, after moving the ignition coils between the engines both started again. So i changed both coils with new ones and the hard start and the cooling issues have gone away.