Kohler Gen Set OS error code

Hello All,


Had a bit of a bad electrical weekend. Hadn't used the boat in a few months, so went out to spend the weekend on the hook. Turns out our hose bank had gone south since the last use.



Anyway, when we shut down the engines anf got anchored we immediately started getting low voltage alarms, so I started up the gen set and turned on the battery charger, a pro mariner 50 amp charger. The water heater was also on. Almost immediately the generator started surging and then shut down, throwing off an OU (over Voltage) code. Started it again and this time it shut down and gave a OS (over speed) code.



I realize it was mistake to try it again.


Started up and came back to the dock. Did some trouble shooting. The charger was pushing over 50 amps non stop and the house bank was not taking a charge. The marine electrician here at our yard came over and took a look. He recommended replacing the bank ( I had my suspicions about it anyway) and the charger. I did both. The charger was under warranty.


Gen set will start, run for a few seconds, then shut down with the same OS code. Both the electrician and I feel like it is a failed sensor switch, but I'm just an owner and he is an electrician not a mechanic.



Anybody got any advice on where to start? It does not seem to be running fast. It shuts down with the main breaker off. It is a Kohler 8KW, 8EOZD.



Thanks.

Sounds like you could have a bad automatic voltage regulator (avr). Start it up without any load and see if it holds rpm then turn on the water heater.

cafesport said:

Sounds like you could have a bad automatic voltage regulator (avr). Start it up without any load and see if it holds rpm then turn on the water heater.

Click to expand...

Thanks for the reply.


It shuts down before it is put under load though.

Ok no load shut down is good now you just have to figure out the engine probs. Start with fuel then air not enough time for a cooling issue. Sensors not sure the Kohler system but most gensets have shutdown logic designed into their systems. Probably at least five sensors to check. Got a manual.

Hey Cafe,


Yes, I have the manual. Unfortunately, in the troubleshoting guide that lists the fault codes for OS it just says "Overspeed" Consult your Kohler dealer. Not much help.



I've been doing some googling and it appears that there is an OS sensor, but I can't find anything telling me where it is. I'm going to call the Kohler dealer tomorrow, they also do Yanmar and I buy all my parts from them. I'll let you know what they say.


I could be wrong, but I feel like it is a sensor that tripped because the charger went nuts and severely overloaded the genset. The OV code that popped up the first time I started it is also a clue, I think.

I'm not familiar with the small stuff but. If I were trouble shooting it. First thing is determine if the over speed condition is true. Hz/rpm are directly related. 1800rpm/60hz for a 4 pole gen. 3600rpm/60hz for 2 pole. If the rpm is where is should be. You need to find out how the genset control is monitoring speed. Most bigger gens use a mag pickup. I have seen smaller stuff use hz based over speed safeties. Once you figure that out. Then you can t/s from that point.

Yep, put a volt/hz meter on gen output and monitor it on startup. Hopefully it runs long enough to get a reading.

Hate the little gennies with computers controlling them. Very difficult to troubleshoot without the full dealer tool set.

Also, Kohlers have like a 6yr warranty, check that warranty might still be in effect.

Had a discussion with our local Kohler dealer/repair shop. He feels that it is likely the control board. The electrician I worked with over the weekend is checking the hz and voltage this week to verify.


Unfortunately, a new controller runs $1K. Ouch. I'm hoping I can find a used one somewhere.

Hopefully it’s not the board. The manual should have a procedure to run through to determine whether it’s one of the relays which would be considerably cheaper.

Doesn't sound as if there are any relays on this set related to overspeed. I could be wrong on that though, I hope I am. I spoke with Kohler today, they have used the same board, an ADC2100, on many different generators across all markets, marine, industrial and home. I am hoping to find a good used one, but so far my usual sources; Google and Ebay have failed me. The part runs $829.00.


Thanks for your help guys. I'll let you know what I find out.

call these guys and see if they can repair it. they do a lot of odd ball stuff and obsolete parts as well as new.



https://www.flightsystems.com/




the way over speed works is the controller will monitor a mpu input(hz) and trigger a overspeed shut down. some controllers monitor the generator hz for overspeed instead of using a dedicated mpu. some very old kohler/cummins stuff used a cable drive overspeed.

Thanks for the tip, I'll give them a call.

Found out yesterday that the controller is bad. $850 hurts but it could have been worse, I guess. I called flight systems and they don't work on this controller.


Thanks for the help.

Glad you got it fixed. Bummer they couldn't repair the old one.