Join Date: Sep 2006
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The thermostat you need to have is the one designed for raw water cooling. There are two thermostat models available, the second one for those owners that have a heat exchanger.... they run hotter. Salt water really scales aggressively at higher temperatures, as a bunch of dissolved salts come out of solution at the higher temperatures, so it needs to be run cooler.
I think you might have the wrong thermostat in there. Pls check the part number. It should be on the packet and on the thermostat. failing that, simply test it with a thermometer.
The thermostat is constantly cycling, as when it opens there is a rapid cooling, and then it shuts again. It's quite a crude animal, but it works ok. Problems start when it sticks open... and you overcool.... or it sticks shut...... then you boil up. I'd sooner have the overcooling mode... stuck open.
It's a very tough motor, very well built, and very heavy. Shame they absolutely savage us for spare parts though. My next motor will be the Japanese Kubota, not because of lack of Volvo quality, but because of the astronomic costs of the spare parts, costs that just about write off the motor if you break something major, and I have. Ten years ago, they wanted £1330 for the exhaust manifold (close to $2600 at todays exchange rate). The motor was 20 years old at that moment. A manifold for the Lister Petter was £185.