The Kohler generator on my 42 keeps popping the breaker  on the back of the unit. There appears to be some anti-freeze in the catch tray beneath the generator, I assume that it is cutting itself off because it is overheating? There is what appears to be an overflow drip tube that is the source of the antifreeze. Can anyone tell me where I can add more coolant? I do not see any place to put it in. It starts up when it is cool but shuts  down shortly afterwards. There is water coming out with the exhaust at the through hull  so it is circulating water.

Any suggestions are greatly appreciated.

Thank you

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Without a generator model number and whether gas or diesel it's impossible to say where the coolant fill is located. How about a couple of pictures?

Sorry, good point. I assumed that the kohler 6.5’s were standard issue.My homework has shown that the cast plug in the manifold is the Phil point. I am starting to think that there is something clogging up the circulation of the raw water which is leading causing it to pop the breaker. But the water exiting the through hull  seems normal so I am not sure. Maybe a disintegrating impeller? 

The "breaker" that is popping is not a breaker, it is a time delay relay reset button.

The the time delay relay takes input from several sources; high coolant temperature, low oil pressure, and start sense.

While it is likely that your problem is an over temp condition, it should not be ignored that the problem can be one of the other test conditions.

Assuming that you have the traditional Kohler heat exchanger which also contains the exhaust manifold, the sea water loop is only a cooling coil that is immersed in engine coolant in the heat exchanger housing. If you are low on engine coolant, the heat exchanger will do nothing and have full sea water flow so observing sea water discharge is only an indication that the seawater loop has flow.

Your generator should have a traditional radiator fill cap on top of the heat exchanger housing. There has been at least one owner that had a separate heat exchanger that was mounted on the front base of the generator. This particular generator had a pipe plug for the fill port. If your generator is like this model, then it is a pipe plug. The fill port is usually part of the overflow tube.

A picture would really be helpful.

Some of the older Kohlers (67 era) had a square head pipe plug on top of the heat exchanger/exhaust man. If you see that you’ve found it.

thx for all the help. I found the pipe plug. Now I guess I need to figure out why coolant is being pushed out of the spill tube...just for future reference this is a 1969 and it has the pipe plug on the top of the manifold, not a "standard" radiator type cap. The spill tube is on the aft side of the gen and it is just a small 1/4" od metal tube. @Ronald...thanks for the walk through on the cooling system...makes sense and very helpful! does this mean there is one raw water pump impeller and a second water pump on the motor?

There is a lot of info in the files section, under generator, Kohler

I have been reading the super disc And I see the pulley driven raw water pump but I do not see where the coolant pump is located. I am hoping there is another  impeller that just needs to be replaced ?

i will get pics next weekend..

Glenn, you may have a generator that is loosing a tiny amount of coolant over a period of time( months or even years). once it looses enough coolant it heats up quickly and boils the rest off thus the overflow you are seeing in the pan. I'd try filling it , running it while checking with a temp gun and see how it goes. Make sure you check it after the first run when the thermostat has had a chance to open and close a few times, it may need a bit more coolant added then before it is full.

you have 3 pulleys  - crank , raw water pump , and engine coolant pump which does not have a rubber impeller.

The Kohler on my 1967-42-Com. would shut itself down------filled thru the pipe plug fill and found a few of the original hoses were leaking-----filled up the water fill replaced the hoses and all is well -----in 20-yrs of ownership-----just two water pumps---2-hoses-----one WP-pulley-----yearly oil changes-----period-----just keeps ticking like a timex !   Bob

Thank you all for the valuable input. As the boat is new to me this season I need to do the standard impeller and hose work on her...our season here is only a few more weeks so I have plenty to do on her this winter. I will refill the pipe plug this weekend and clean the tray and see if there are any obvious sources of the leak.

Thanks gain for taking the time to help!

I have replaced the hoses and impeller and I am going to order a coolant reservoir. Is there any reason not to have an overflow container for temperature expansion like a can connected to the drip tube and also provide extra coolant for the generator to draw up if required?

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