Generator spews coolant from overflow

[IguanaSwim]

My generator is a northern lights 6KWH
Model: M6732-52637

It squirts coolant from the overflow hose when I start it.

Yesterday I found a broken hose clamp on my heat exchanger end cap hose, as illustrated. When I replaced the clamp today and started up the generator, the coolant came pouring out of its overflow spigot. The coolant now lies far above the normal line.

Should I drain down the coolant to normal level and start again? I don’t understand why I should have more coolant than before unless maybe it’s due to my have closed off the water leak on the rubber elbow off the head exchanger.

For many days I’ve noticed the slight tang of coolant in the engine room. Maybe it has been leaking?

I’ve just sailed from the Caribbean into the Chesapeake so I doubt that warming up could account for the overflow.

[Lepke]

If you're indeed gaining coolant the only place it can come from is the heat exchanger. Usually the coolant is at a higher pressure than the salt water in the HE. So any leak will put coolant into the salt water stream. But at start up, a cold engine can have a lower pressure and draw some salt water in.
If you're not gaining coolant, but having overflow, then you could have a leaking head gasket. Take the cap off, start the generator and see if there are bubbles in the coolant.
Some auto parts stores will loan/rent a radiator pressure tester. If you have a standard filler, the tester attaches and you pump up pressure and see if it holds. Do this with the engine off.
If your HE is leaking, most radiator repair shops can fix it.

[thinwater]

Originally Posted by Lepke

If you're indeed gaining coolant the only place it can come from is the heat exchanger. Usually the coolant is at a higher pressure than the salt water in the HE. So any leak will put coolant into the salt water stream. But at start up, a cold engine can have a lower pressure and draw some salt water in.
If you're not gaining coolant, but having overflow, then you could have a leaking head gasket. Take the cap off, start the generator and see if there are bubbles in the coolant.
Some auto parts stores will loan/rent a radiator pressure tester. If you have a standard filler, the tester attaches and you pump up pressure and see if it holds. Do this with the engine off.
If your HE is leaking, most radiator repair shops can fix it.

1. Test the coolant for chloride. If there is a HE leak it will be obvious.
2. Low pH, high glycolate, and rust in the coolant are all signs. The oxygen causes breakdown of the glycol, generate acid, and causes rust.


Pressure testing is fine ... but leaks can be temperature dependent. The coolant tests will tell you for certain if it is an on-going problem.

[Tsuru]

Blackstone labs provides analysis on oil and coolant (among other services). I've used them for engine oil for years and am pleased with the service.
https://www.blackstone-labs.com/tests/tests-price-list/

[skipperpete]

Originally Posted by IguanaSwim

My generator is a northern lights 6KWH
Model: M6732-52637

It squirts coolant from the overflow hose when I start it.

Yesterday I found a broken hose clamp on my heat exchanger end cap hose, as illustrated. When I replaced the clamp today and started up the generator, the coolant came pouring out of its overflow spigot. The coolant now lies far above the normal line.

Should I drain down the coolant to normal level and start again? I don’t understand why I should have more coolant than before unless maybe it’s due to my have closed off the water leak on the rubber elbow off the head exchanger. Consider the possibility that the crappy NL mixer elbow is restricting the raw water flow, usually the raw water pressure is quite low but a blocked elbow can push it up to coolant side pressure …….and make the pressure cap leak and exit via the expansion tank pipe.

For many days I’ve noticed the slight tang of coolant in the engine room. Maybe it has been leaking?

I’ve just sailed from the Caribbean into the Chesapeake so I doubt that warming up could account for the overflow.

YES, the broken hose clamp on the tubestack end cap is far and away the most likely cause of coolant getting ejected from the overflow once you have raw water pump pressure getting into the coolant side of the circuit. The problem with simply replacing the hose clip is that its not easy to get an endcap back into the best place on the tubestack cylinder, especially if the endcaps are old and less flexible.
And if seawater really is displacing the coolant, you need to flush and flush again that little engine with fresh water, hopefully you have a tap on the block drain plug, it can be a bit of a trial undoing that big block plug.

[IguanaSwim]

Now that a mechanic has repaired my generator I can say thank you for getting my brain in motion on the possibilities. It turns out that my boot or the rubber connector off the heat exchanger was cracked. further, the heat exchanger seems to have been worn out. In fact the Manuel warns you to take heed of it at 2500 hours. So I ordered a replacement from The web. It wasn’t horrible slotting it in. Didn’t even have any gaskets. And now it runs fine.
Again, much appreciated.