Join Date: Jul 2008
Location: Hershey, PA / Middle River MD
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Volvo MD7A Overheating Solved?
Since I purchased the boat in the fall of 2008, I have had a minor overheating problem. It exists when the sea water is warmest (July to September) and when the engine is being run over 2,000 rpm (max design is 2,600). I have dealt with the problem by motoring between 1,200 and 1,800. After reading several Sailnet posts suggesting blocking in the exhaust manifold, I decided to remove the manifold. This only took 20 minutes and I was happy to see a lot of fairly easy to remove crud in all of the cooling water passages. Most of it was located at the interface between the manifold and the head so it was easy to get to and fairly easy to remove. The gasket seemed undamaged so I didn’t replace it. Between the engine manual (showing a diagram of the cooling flowpaths) and probing around in the manifold and thermostat cover, I believe I have figured out exactly how the cooling system in the engine works and I’m confident I have solved the overheating problem. I’ll know for sure next spring when the boat goes back in the water. Attached are photos. If anyone has any comments or questions, I might be able to help with, please let me know.
Last edited by harbin2; 12-08-2010 at 11:37 AM.