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richard5933

Kohler 12.5 RCOP67 Generator

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I've made some great progress on our generator, but there is still one issue left to resolve. I'm hoping that someone with more experience with these old beauties can help out.

The generator is a Kohler 12.5RCOP67 spec 96562B powered by a Perkins.

The generator is generally running fine. It puts out 120v @ 60hz, and the Perkins is running great now that I had the fuel injector pump rebuilt. The problem is that the cranking reset button pops after running it for a short while, as if the engine is overheating.

The thermostat is new, the water pump has been replaced, the radiator is fine, and the unit will run for hours with temps steady at 160 degrees according to the gauge on the dash. Oil pressure seems to hold steady at 40+ and I’ve never seen it drop while the engine is running. I don’t think that there is an actual cooling problem or oil pressure problem with the engine, except for these momentary problems.

Here’s what happened this past weekend – started the Perkins, it came to temp, ran at 160 degrees for about 10 minutes, then it shut down. I didn’t see the temp at the moment it shut down, but it had been fine just a few moments before. We had about a half-load on the generator when it shut down. Circuit breaker on gen controller never moved. I went to the controller and sure enough the red cranking reset button had popped out. Pushed it back in and the engine started right up and was at the proper temp. Ran for quite a while (an hour or so) after that with no problem.

So, I’m wondering if the cranking reset button itself is going bad? Does this happen? Or is there some other issue which could cause the cranking reset button to pop out and shut down the generator.

1974 GMC 4108a-125 54.JPG

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Is the cranking reset button a circuit breaker? If so test it for current load or try another one.  Years ago I was a Kohler dealer but my techs did the work so my experience its limited.

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Seems to be a relay (1TS) with a heat coil in it. Three things can provide the ground connection to the relay: oil pressure sender, water temp sender, and CC relay.
Checking with a Kohler shop on the east coast, I was told it could be a bad 1TS relay, bad CC relay, or bad sender. Only the senders are a available through normal retail channels.

 

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Richard, The reset buttons can be an issue. I do not have the reset wiring circuit memorized, but I kind of remember there is a temperature and oil pressure safety circuit setup. 

If the generator restarts quickly after a shutdown and it starts right up after resetting, I would just replace it. It is no longer a spring chicken.

Do you have a "J" series temp probe with your meter? Hook it to the cooling system and see what the reading is, also! the oil pressure sensor resistance reading should not jump around while measuring ohms.  The devil can be in the wiring details and where is the circuit power being supplied from? , but in your case the the reset is number one on list.

Rich.    

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I found a replacement for the crank reset button. I'll change it out and see how things go. Otherwise, this old generator might last us another season or more. I think that once I change out the fuel lift pump (low pressure pump) I'll have all the drips taken care of for now, at least until the next one pops up. Boy, do these old Perkins love to drip.

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