O.K., I've replaced the impeller which had a number of broken blades, I located and removed all the missing blades (an more!) from the heat exchanger, I removed the heat exchanger and had it acid cleaned since there were plenty of clogged tubes, I removed and replaced the thermostat, and still the engine runs hot (about 200-210). I also removed the thermostat entirely and ran the engine and the temperature never got above 122, so I figured that told me the thermostat was the problem, but a new thermostat did not fix things. What can I do next?????
Engine overheating problem!
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Test the new (and old) thermostat in a pan of water on the stove.
After reading some other threads on this issue, I'd like to add some information. My hot water heater is disconnected, at least the hoses bring cold water in and hot out. The hoses from the engine are still connected. I have no idea if there is any water in the tank, I suspect not.
Vasco: I'm looking into the exhaust elbow.
donradclife: i tested the old thermostat on the stove and it opened, but after removing the thermostat entirely and running the engine with no overheating I figured the old one was not opening completely so I replaced it but didn't test the new one.
Vasco: I'm looking into the exhaust elbow.
donradclife: i tested the old thermostat on the stove and it opened, but after removing the thermostat entirely and running the engine with no overheating I figured the old one was not opening completely so I replaced it but didn't test the new one.
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Doodles, test the new one. Sometimes they are DOA out of the box and simply don't work. I learned that the hard way.
And of course, making sure it is the correct new thermostat and facing the right way. Sometimes, the wrong part gets into the box. Don't ask.
And of course, making sure it is the correct new thermostat and facing the right way. Sometimes, the wrong part gets into the box. Don't ask.
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If the engine is raw water cooled you may have a scale build up which will restrict water flow and make the engine run hotter.
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5,339 Posts
Since the temp is only 122 with the thermostat out, the problem has to be in there in some fashion. I have not been pleased with the replacement thermostats sold by Universal/Westerbeke. They don't last and do a lousy job of maintaining the correct temp. And the price has risen four-fold in the last 10 years!
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I've been reading that lots of ppl has temperature reading for their cooling water out from engine. This interest me. I've Yanmar 2GM20F. Anyone has photos of the setup ?
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I have a 2GM20 which I installed myself in 1995. I have had overheating problems twice and both involved the exhaust elbow. I have a brass elbow which connects the water discharge line into the exhaust elbow once it was blocked with carbon the second time it was blocked by scale in the exhaust elbow. A long skinny screw driver cleared the debris both times. I now check the elbow each season. The engine normally runs below 180.
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Doodles I agree with JimCAL, it would seem to be a thermostat problem, do you have the manual which shows the cooling water circuit on both sides of the heat exchanger? Examine the area where the thermostat is installed and be sure it is not blocking a port, could be the wrong thermostat which seems almost impossible. Also check the gasket and be sure it is not blocking a port. It is not adding up.
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Bear in mind that Westerbleech manufctures just about nothing, they just assemble comtracted parts. If you can find out who the real manufacturer of you engine block is, the odds are that NAPA has the right thermostat for $5-10 for it.
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