MD7 Thermostat: To be or not to be?

[V. Melendez,S/V Ala Libre]

Hi All.

Ala Libre´s (CD 30 C) Original MD7 engine´s cooling system is connected to a heat exchanger which in turn is hooked to the water heater. This arrangement has worked well over the years but recently the engine has started to run hot. The thermostat is the prime suspect. Due to the very difficult job of replacement and the trouble to get the part it has crossed my mind to remove the thermostat once and for all. Our boat is based in the Caribbean where the climate is always very warm, so I figure that the thermostat´s function of mantaining high temperature when the weather is cold is really useless here. I would like to know if my thinking is right before I embark on the thankless task of removing all that hardware in a very unconfortable space. Like it has to be done right the first time. Opinions, anyone? Thank you all.

Fair winds.

VM

[Guest]

I had a Volvo mechanic here in Annapolis look at the MD7A in Kittiwake. We had the same discussion, and removing the thermostat was one of the first options that he brought up. Some of it had to do with the fact that there are not earlier opening thermostats available for the MD7A.

We also talked about SpeedSeal, impellers, mufflers, and repowering (only out of curiosity). The current estimate for repowering here is well above $10K - so taking good good care of your engine is well worth the effort!
Peace and Fair Winds, Bill

[Mike Rodriguez]

Hello VM,
overheating could be several reasons. Check your impeller, sometimes blades break off and clog the system. You may need to remove the manifold and thermostat housing and clean them really well. Soak them overnight in an acid solution (15%). Once the thermostat is out you can check if it works using a pan of water on the stove. This would be a good time to install new gaskets. Take care not to break any studs off in the block. I would not get rid of the thermostat.
By the way, I also have a CD30c in the Caribbean. My phone number is, (787) 565-9450.

Cheers!

[Danno]

my guess is it's your heat exchanger-has beome scaled and as a result has a redution in flow.

I would start withthe heat exhanger.