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.
The cranking reset button you discribe is a latching relay, and they can get weak.>>>Dan
Quote from: Utahclaimjumper on May 09, 2019, 06:22:30 AM
The cranking reset button you discribe is a latching relay, and then can get weak.>>>Dan
Any way to rebuild the relay or is this something I need to start searching for? Where would I even find one if replacement is the option?
https://apelectric.com/generator-parts/kohler-generator-parts?page=3
Quote from: Dave5Cs on May 09, 2019, 06:59:48 AM
https://apelectric.com/generator-parts/kohler-generator-parts?page=3
Thanks. Not seeing any parts for older genset like mine, but I'll give them a call.
My Kohler guy on the east coast thinks that it's either the reset button relay (1TS) or the CC relay (which trips the 1TS)
I have a kohler generator Kohler powered air cooled propane fueled, I am having issues with relays that go to the inside remote board, the relays are made by guardian and no longer available, I have found others locally but they are larger and wont fit in the relay box so I am rebuilding the whole works with 3 new relays one of which is latching, >>>> John.
We had one like that on our Koehler, but it was at the end that was back in the bay. Had to roll it out on slide to reset it. Ours only kicked if starting generator and not allowing enough time to come full up to speed before kicking on AC's. Richard, remove electrical box cover and make sure the wires from the generating head are tight and not showing stress or discoloration from overheating. We experienced that on ours. Cleaned and retightened connections, and never had issue again.
Quote from: richard5933 on May 09, 2019, 07:18:59 AM
Thanks. Not seeing any parts for older genset like mine, but I'll give them a call.
My Kohler guy on the east coast thinks that it's either the reset button relay (1TS) or the CC relay (which trips the 1TS)
I'm not sure what the "CC" relay is, but having had a lot of experience with safety shut-down systems I think he may mean the temperature switch that is screwed into the engine. Just jump the two wires at the temperature switch and see if it solves your problem. if so, get a new NC switch. Plus, I might add, 160F is too low a temperature for your engine. You want it 175-180F.
Quote from: Geoff on May 09, 2019, 01:39:31 PM
I'm not sure what the "CC" relay is, but having had a lot of experience with safety shut-down systems I think he may mean the temperature switch that is screwed into the engine. Just jump the two wires at the temperature switch and see if it solves your problem. if so, get a new NC switch. Plus, I might add, 160F is too low a temperature for your engine. You want it 175-180F.
The relays in the Kohler control box are labeled to correspond with the wiring diagram. The two in question are labeled CC and 1TS. There are longer part numbers, but it appears that they are referred to as CC and 1TS by the Kohler guys.
I've got a Murphy switch which I can use to make a new shutdown circuit. The low oil pressure and high water temp senders appear to function correctly, and they could be used to trigger the NC circuit in the Murphy switch to open. This is what I did on our first bus when we discovered our control box was FUBAR -- we replaced the generator head with a new one. Generator head came with its own controls, but did not have engine shutdown controls.
When I got the current Kohler/Perkins it had no thermostat at all. My suspicion is that the previous owner encountered the shutdown problem and thought that perhaps the thermostat was faulty and causing the engine to overheat. His solution was to pull the thermostat.
I bought both the 160 and 180 thermostat for the Perkins. The tech helping me with the generator thought it best to install the 160 thermostat at first, in case the engine wanted to run hot. With the 160 thermostat in there, it runs somewhere between 160 and 165.
Eventually I will be swapping the 160 out and putting in the 180 degree thermostat in the engine. Just have to find the time and energy to pull the thermostat cover. Fortunately we installed a petcock on the top of the thermostat housing when we put in the 160 therm. so it will be pretty easy to drop the coolant level and then refill afterwards.
Richard
I have the same Perkins 4-108 12.5 kw Kohler generator in my 74 mc8.
I had to replace that little circuit breaker it started acting the same as yours. If I remember correctly it works like a time delay circuit breaker. I ended up using a time delay relay.
Not the best but at least it's still has an auto shutdown
Rick 74 MC-8
Quote from: Rick 74 MC-8 on May 09, 2019, 03:11:09 PM
Richard
I have the same Perkins 4-108 12.5 kw Kohler generator in my 74 mc8.
I had to replace that little circuit breaker it started acting the same as yours. If I remember correctly it works like a time delay circuit breaker. I ended up using a time delay relay.
Not the best but at least it's still has an auto shutdown
Rick 74 MC-8
The little spring-like think sitting on top of the relay/switch is a heat coil. When a ground is applied to it from a fault (high temp or low oil pressure) it heats up and will trigger the relay to shut off. That heating coil is the time delay - without it the engine would have trouble staying running for the few seconds it takes for the oil pressure to come up.
I did find a replacement for this and hope that it will be the solution. If not, then it's time to start troubleshooting further down the line.
There's always the Murphy switch if I need.
I posted this before anyways www.flightsystems.com are good to go for parts on the older generators ,they have online trouble shooting and videos for RV generators free of charge
I found a replacement for the crank reset button/relay. I'll see if that takes care of the problem.
I did contact flightsystems on another older generator I'm working on which is similar to the one in our bus - they mainly work on the newer generators, so they directed me towards another outfit that makes parts to work on the old-style Kohlers. Not cheap, but at least there are parts out there when needed.
Following one of Cliff's earlier references to flightsystems, they were very helpful and possessed the expertise to troubleshoot a twenty year old Generarc RV unit. Had a rebuilt board in stock and got it sorted out.