8eoz kohler genset shuts down with too much load after it heats up

If it runs good all day with a light load but shuts down in 15 minutes with a full load, it would make me look at the heat exchanger, the internal water pump that circulates inside the water jacket. You may have impeller fins in the end your heat exchanger or just mineral buildup in the tubes. Good Luck, Steve

I agree - it sounds heat related or at least that's a fair possibility since under load a lot more engine heat is produced. IF the cooling system is not up to the task, the heat sensor shutdown may just be doing its job.

"Hey Reb why would it run with a light load but not a full one if it is overheating?"

Mike P just posted one possibility....or a marginal thermostat, or a marginal heat exchanger, or a faulty sensor that is "premature"....

...but no matter what the cause, sometimes things are not entirely "logical", like that fuse situation I described on Bill's boat.

boatsb: "..it's hard to diagnose remotely.." yes....
It's hard enough to make good guesses remotely, and too often the poster with the problem doesn't reveal all the facts and observations....because they don't seem important.


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Coin operated: What's your basis for posting "not overheating"....That's an important detail. Can you or have you double checked components for temperature with an infrared thermometer? Have you the same temperature reading as in the past???

[My own 12KW 1972 Onan diesel generator did not have a temp gauge for the first five years I owned my boat....when I put one on and mounted it in the salon so I could monitor, I found it running about 15 degrees hot....but it never shut down. I previously posted the whole story in all it's gory detail. Anyway, I finally traced it to a significantly blocked heat exchanger which I cleaned....during all that I also discovered some of the shutdown sensors were NOT wired properly!!! On used boats you might find ANYTHING.)

If a coolant temperature gauge, for example, has always read low it might not correctly disclose a high/marginal operating temperature. I don't know Koehlers specifically, but if it has an exhaust elbow shutdown sensor like many Onan's, there might be a marginal raw water flow, enough to cool the coolant via the heat exchanger but enable the exhaust elbow sensor to overheat and alarm.

Whatever, good luck, "the devil is in the details"....all the above posts are possibilities but dependent on your exact symptoms....

Ya just got to be there.:D Get that heat temp gun out and start looking and shooting temps and writing them down.
BILL

"genset will run all day with light load, or no load, genset has remote panel plenty of oil pressure, removed sound shield place my hand on exhaust elbow, cool to the touch,"

heavy load = more heat

the elbow may be cool and you may have enough flow to keep it cool enough but either not enough to prevent temp from creeping under heavy load OR even with enough raw water flow your cooling system can't handle the extra hear.

if raw flow is low, you're likely to see some steam out the exhaust (and a different exhaust note)

you need to check the temp on the cooling system, usually a reading at the Tstat housing will tell the story.

i'd start there, and if it is indeed hot, look at the basics: impeller condition, old impeller bits at the heat exchanger inlet, low coolant, etc...

if the temp if ok at the Tstat housing when it shut down, then temporarily bypass the overheat sensor.

Or it could be the electronics. FYI the higher the load the higher the current therefore the higher the temp of the electrical components.

It may have nothing to do with the cooling system.

I don't think the generator portion has an engine shutdown switch associated with it. I don't know about the Kohlers but my NL has a circuit shutdown (breaker) which will shut off the generator output in the event of an electrical issue but the engine will keep running.

yeah but it's a lot easier than checking actual coolant temperature than troubleshooting an electronic control board problem.

The fuel solenoid is normally closed. The electronics control that and are usually on the same circuit board as the generator ends controls. If it heats up and gets a bad connection, low 12 volt or other electrical issue in the circuit board it could cause a lot of problems like this.

Check the high temp shutdown switches. They go bad every decade or so. My diesel had two, one on the side of the engine water jacket, a second hidden on the muffler. I think they were about 195 degree switches. Like a Halloween clicker. They pop with overheat, reset with cooling. I knew I had one but it was the second that went bad. I think I remember they connected to the wire at the top of the fuel solenoid and broke the circuit as they tripped. If you jumper around a bad one while it's hot (engine just stopped) the solenoid will click in. You will hear it and you're done!