Mackattack

2001 kohl 5 kw generator with 30 hrs keeps running hot. Changed impeller, good return flow of water out of side of boat. Return water is warm to touch, but engine hits 200+ in just a few minutes and safety feature kills engine. Under full load from A/C causes it to run hot in less than a minute.
Tried the following
New impeller
Removed Thermostat
Filled coolant in heat exchanger

Anything else I am missing? Cabin is useless without the generator and A/C

45Tripps

Did you check the incomming water strainer. There should be one in line. They sometimes get stuff in there that will restrict the incomming flow somewhat, but your exhaust output is still decent because the water muffler fills with water. Also check the pickup on the bottom of the boat and make sure there is no damage or blockage there.

Also check the impellar housing in/out ports and flush the entire cooling system with a water hose. If an impellar came apart at some point, it can get stuck in the passages and restrict flow.

If possible run the genny on a hose at the house or marina. You can go to home depot and get a standard home washing machine rubber water supply hose, cut off one end. You will find it will slide into the water supply line of the genny perfectly. Use a hose clamp on the genny hose to tighen up the fit.

Pull all the lines and flush them forward and backwards, then run it on the hose. If it still runs hot replace the temp sensor.

If this doesnt work, call Kohler.

Westcoast

Kohler's will trap air in the cooling system. If you changed thermostat there is a good chance you have trapped air that needs to be bleed out. Good luck.

bobl

I second the trapped air idea. We just fixed an overheat problem that was an air lock on a 5k Kohler.

Mackattack

Can you tell me the steps to eliminate the trapped air?

Mackattack

Bump

plumbers crack

I sent you a pm awhile back regarding the shut down issue. There is a small plug in the top of the manifold that you can remove that will purge most of the air out. Make sure the coolant level doesnt drop too low.

You can also call kohler they have a bulletin on air locking which stops the circulation and cooling. When I owned the boat it had like 5hrs on the gen and I couldnt believe it would shut down.It took 2 mechanics to figure it out, after replacing the impeller and thermostat ect. once bled it ran great. Couldnt believe it was that simple.

good luck

Westcoast

+1 good advise.

Several different models out there. Each one is a little different.
Get the service manaul or call kohler if you can't find the bleed plug.
Good luck... Hopefully u have some access to the unit. You should
See some of the ones I have had to work on!

Mackattack

Problems fixed, I think

I found a 1/4" plug on top of the heat exchanger opposite the coolant cap. Removed the coolant cap and the 1/4" plug. The coolant cap side of the exchanger was almost full, I topped it off. The other side of the heat exchanger (1/4" plug side) was dry. I ran the generator with both caps off. The coolant cap side went down a bit, so I topped it off again. The small plug side was splashing coolant out from the vibration of the motor.

There is almost no way to fill the 1/4" cap side. I used a large syringe with a small tube to fill it. It took almost 1/4 gallon of coolant. Replaced the plug and cap.

Cranked up and the generator runs fine, 210 degrees F under load, powering the ac unit and battery charger at the same time. I let it run for an hour and let the ac compressor cycle several times. Never ran hot to the point of safety engine cut off.

Should I re install the thermostat? The generator didn't have one when I took it apart.

maldo105

I have a Kohler 5 kw in my boat I used without problems but now I tried turning it on but it doesn't do anything. The battery is new as well as spark plugs but the machine does nothing. Can anyone tell what's going on? Thanks.