Volvo Penta MS 2V Overheating

[Silvio]

hmmmm,
Sounds like you are checking all the right things. These diesels are pretty simple creatures when you get down to it. What tells you that you are over heating? Is it the gauge reading only or do you see and smell an over heated engine?

I don't mean to sound obtuse but are you certain that you are over heating and not that you are having a gauge problem?

Have you tried removing the thermostat and running the engine with it taken out of the picture (essentially in the always open position)?

Are you in particularly warm water that is interfering with the heat exchange, maybe causing a higher than typical reading but not actually over heating? Good oil level?
Good air flow around the engine cowling (not piled with gear) ?

Again, I'm sure you already checked these things but just throwing them out there in case.

Good luck.

[sony2000]

Another post found the problem to be a partially clogged exhaust manifold. Easy to remove and claen.

[mitchbrown]

You should verify that it is actually over heating, this can be done with a infrared thermometor which can be purchased on ebay pretty inexpensively. I had a C&C with a yanmar that had the wrong sending unit installed and would cause the buzzer to go off when the engine was not actually overheating. A bad sednding unit can cause the same problem.

Mitch

[d-p]

Definitely overheating. Coolant boiled out of the reservoir when I took the cap off, smoke and smell from oil residue on engine. Cleaned exhaust manifold last year. Plenty of water coming out the exhaust. Haven't run it without the thermostat, If I don't find anything else obvious I will try that.

[sony2000]

No doubt the impellor of the water pump is new. But as years go by, the shoe (cam) that it hits to send the water along, wears down and should be changed.

[Minnewaska]

What are you running your motor for 2 to 3 hours for? Easy fix.

Just kidding, happens I know.

You say you cleaned the exhaust manifold. Did that include the mixing elbow? If clogged, you would not get sufficient flow. I do not think it is possible to visually gauge the amount of water coming from the exhaust, only whether you have any.

You RW pump may not be doing enough work. A one year old impeller is ready for replacement in my book, even if it looks good. The interior of the pump can be worn and not pumping at max efficiency or, if it's belt driven, the tension may not be sufficient. Although, too much tension will wear the belt out. The suggestion to replace the cam, if serviceable, is possibly a good idea.

Again, just because you see lots of water in the exhaust, does not mean there is enough.

[Silvio]

d-p,
Did you find the culprit?
Let us know what it turned out to be, inquiring minds want to know.