generator issue

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WALSHIE

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I didn't want to hijack the other thread regarding generators but as mentioned, Kohlers can be a PITA. I have a 7.3 Kohler, I assume around 2001. I admit to being the person that does not use it! There's no easy way to run the carb dry so I don't do that when winterizing either.

I want to get it working! I change the impeller, removed and cleaned the heat exchanger (was fine), oil change, etc. It starts with the help of staring fluid, can power the boat. But it shuts down after say 10 minutes. I wish I knew why! How can I check for overheating? The exchanger is cool when it shuts down, I guess I should check the thermostat next but I wish I knew it shut down from overheating.

I'm hoping I can run it frequent enough to self-clean the carb with clean fuel...is this a pipe dream?

I've read where people say "change the spark plugs" but really?? Do you guys believe that?
 
Use an IR Gun and check the temp at the temp sender to make sure it s not overheating the by pass the overlay switch to eliminate a bad sender.

Does it shut down abruptly which would indicate A safety Switch is shutting down. If it starts stumbling then it is likely to be the carb or ignition. And yes Kholers are plug eaters. Start there
 
Shuts down abruptly, Any idea where the overheat sensor would be? Or the low oil pressure sensor? I can put a meter on it. I'm tempted to add permanent gauges, I like information. (Oil, Temp, Volts)
 
I have the same unit, same year. I'll offer this suggestion, but I don't think it is your problem. I had a lot of problems last year and it turned out to be the anti siphon valve. Sooner or later, it will cause you problems and when it does, you will be pulling your hair out trying to figure it out.
 
I don’t know how the Kohlers are wired. The oil pressure and over heat switches should be easy to spot. Usually they are simple on off switch. Some open when alarm level is reached other close. When you find the switches use a meter to see if they re open or closed by checking continuity between block and terminal.
 
Check the exhaust when the generator is running is it making water or is it dry?

Look at the service manual for your model.Some Kohlers have a plastic sleeve that connects the impeller drive to the shaft (others have pully). if this sleeve is broken then the impeller does not turn and engine will overheat and shutdown.
 
Thanks blue_nova, water is pumping. I replaced a torn up impeller and removed the heat exchanger to inspect for lost rubber vanes. Water pumps fine for the 15 minutes then it shuts down. I did see a you tube video describing the issue you mentioned but I don't think that's it. Someone mentioned air lock in the system, I will try to bleed from the 3/8" brass 'plug' but my 'plug' is really a zinc ... as it should be.
 
Again before testing down the cooling system take an IR Gun and measure the coolant temp near the Tstat and see what it does. It should come up to 189/185 and stabilize. If it keeps creeping and then the genset shut down at say... 200... then you know you have a cooling issue. Otherwise look elsewhere
 
Will it run longer if there is no load on it? Try a couple of tests. Fire it up, put a large load on it and wait for it to shut down. Then try the same test but no load. Marginal cooling might let it run longer. Perhaps the exhaust elbow is clogged.
 
My Kohler used to do this. Changed the plugs and runs fine since. Don't ask me why because I don't know why Kohlers eat plugs, but they do.
 
You stated "I replaced a torn up impeller" but not I also found ALL of the missing bits.

Not enough water may be getting through key parts of the exchanger. Get an ir thermometer gun
and test temp at input and output of heat exchanger. This will tell you if it indeed is overtemp
shutdown, which is most likely.

When you had the heat exchanger off and shook it did you hear any rattles? There should be nothing
inside that rattles.
 
I finally had some time to look into this some more and brought my IR temp gun.
1) There is plenty of water out of the exhaust.
2) I removed the brass plug on top of the manifold and added coolant as suggested on another site, in case there was an air pocket.
3) As suggested, I checked the temp from cold start up to shut down
- The manifold ran from 180 degrees up to 200 then shut down
- The outside of the heat exchanger never really got more than 80 degrees, if I recall right.
4) For kicks, I went to the auto store and bought more plugs - this did not help
5) I plan on taking the heat exchanger off, inspecting it BETTER than what I did
- While doing so, I will check the thermostat
- I will also blow out the exchange coil and look for more broken impeller parts.

Thanks everyone for any and all suggestions. This is not a high priority but I would like to see it working!
 
The manifold isn’t the best spot to measure. Best is at the Tstat or on the hose leading to the Tstat. You want to get an accurate reading on coolant temp.

Plenty of flow at the exhaust means it s unlikely you have a restriction at the heat exchanger. Could be an issue with the circulation pump going bad and not circulating enough coolant
 
Thanks Pascal, perhaps "the manifold" was a poor description. I did measure on both sides of the thermostat. It makes sense the outside of the heat exchanger is pretty cool since sea water is flowing. I will take the heat exchanger off, test the thermostat on the stove, blow out the coil, make sure that is squeaky clean. If it happens again, the last area to look for would be coolant not being pumped as you suggested. For that test, I will slowly pull off the hose to the heat exchanger and hope to find a steady flow of coolant squirting back at me (while running).

The boat is a 2001 so I assume the generator is about the same vintage (Kohler 7.3e) but it does not display the diagnostic codes as to why it is shutting down, I wish it did so I can be certain. But there are only three codes: Low Coolant, Low Oil, Overheat. I'm 90% confident it is overheating.
 
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