Volvo MD11C overheat

[rodolph]

My 1979 Westerly Centaur has the original MD11c engine which performs admirably apart from the fact that if running in excess of 1800rpm will after some variable time interval stop moving water through the cooling system and of course overheat. If detected in time then throttling back will eventually result in water again passing through the cooling system and temperature returning to normal. Engine is regularly serviced and seacock and cooling pipes have been chacked for obvious obstructions. Any suggestions?

 

[thalassa]

Got a similar problem last spring with my MD7a . After a while, generally an hour or more, but preferably when starting the engine in an emergency, the cooling water would just stop. Overheating would result, of course. Changed the O-ring on the strainer, all flexible tubing, checked the Jubilee clips. In the end it emerged that the brass pump cover was at fault. It had been and scored by the impeller and the silt in the seawater. I brought the cover to a machine shop and had it ground down 0.3 mm . You would never believe the difference it made to the impeller's pumping capacity!

 

[dah]

Rodolph, have a look at 2 previous posts
1. MD11C PROBLEMS dated 09/2001.

2. ENGINE COOLING dated 03/2002.

You may get some useful info from these. Hope this helps

DAve Hanna

 

[nickdick]

I had a similar probelm last year on my MD7a. We found that the inner lining of the rubber exaust pipe had delaminated and when on high revs it `enveloped` and stopped the water. Back on to reduced revs and problem went away. Apparently you only have to over heat a couple of times to wreck the inside of the pipe. Worth checking. Also hollow exaust noise was heard when this happens.

 

[rodolph]

Finally got round to sorting this out. The inside of the exhaust hose was not a pretty site, so have replaced. Await sea trials to see if makes a difference. Thanks for the suggestion.

Tony Grellier

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[rodolph]

Impeller plate looked a bit scored so have reversed and polished as suggested by somebody in response to someone elses problem. Await sea trials for results.

Thanks for suggestion.

Tony Grellier

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