Does your MD 7A overheat?

[fenixrises]

Hi all,

A heads up to the many owners of CDs with a Volvo MD7A.

During my boat rebuilding process I am checking over the engine.
The engine seems fine rune well and still starts easily.

During the passage down from Virginia I never ran the engine hard for long periods so had no problems with overheating.

BUT!!! To let you know...

I removed the water pump, thermostat & housing and those pesky little copper tubes that connect everything together.

The tubes and seals were in good shape... do use gentleness when disassembling and Vaseline or some such when reassembling.

Throughly check all for blockages.

I found an impellor blade lodged in the copper tube just above the pump. This restricted about 60-70% of the tube's inside diameter.

This tube goes from the water pump forward to the themostat housing. What some may not know is that there is also a tee in this line. The tee goes into the heat exchanger/ exhaust manifold at the aft lower end. This joint is almost impossible to see.

When I removed the pipe I found the tee passage completely blocked with black crud. If you are having overheating problems remember this.

For overall clean up I found "Lime-Away" very helpful. This is a common household product. It is very acidic so be extremly careful when using.

Take care,
Fred B

[Bill Watson]

As always, your comments and observations are appreciated. The MD 7A in Kittiwake runs warm, but not too hot. I'm going to start looking at the cooling system next week. I have noticed in the last week, as air temps have cooled down, that she is running noticeably cooler. Is that possible, I would have thought that it would be water temperature, and I wouldn't think that it has decreased enough to make a difference, althought haven't checked surface water temp. Have been putting some long runs under power (7 hr today), and so far, so good. The teak cockpit grate is great!

Peace and Fair Winds, Bill