"Gunk" in generator coolant

I winterized the 5kw northern lights generator (490 hrs) yesterday in our new to us trawler. In checking the coolant I noticed a large accumulation of a gummy, waxy substance covering the inside.

My question is A: what is it, and B: how do I get rid of it.

Thanks in advance for your comments!

This may not be good. Compare the color of new fluid with the old (assuming you use the same stuff). Check for salt water dilution of the fluid. It could be merely very very old fluid or something more. Regardless, have the system thoroughly flushed and have the heat exchanger checked for leaks.

I dont think its time to hit the panic button quite yet.

It could just be the coolant breaking down. You didnt mention what color it was. Is this the first time it has been drained out?
I would just drain it out, refill it with water , run it for a half hour or so, and drain it again and see what that looks like. If all is good , just add new AF.

bligh said:

I dont think its time to hit the panic button quite yet.

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Agree I let mine go too long once and it looked like something had died in the cooler. When antifreeze breaks down, it looks ugly!! Suggest do as the previous posts suggest, drain, flush and refill.

Gummy, Waxy. Sounds like the wrong type of antifreeze possibly made worse by being too old.

Generally you should use a low silicate diesel rated A.F. Check the mfgrs. manual for recommendations.

Silicates will produce a gummy, gooey mess which can sometimes be a problem to remove.
I had it a bunch of years ago although it was just a hint starting and I dumped the A.F. as soon as I found it.
If you are lucky and use good stuff you will get away with it.
For now, as suggested, refill with water and run for a bit, 1/2 hour under a good load, and drain again and put in the new A.F.
Change the A.F. every two years. You might want to carefully check periodically after this change to see if any more appears or if it, hopefully,seems to be reducing.

If a bunch still shows up you may have to do it again and MAYBE use a cleaner.

Sounds like a mix of 2 AF that was not compatible.

Nalcool ,2 part cleaner , and flush flush flush!

And when you refill be sure to use the extended life coolant that the genny manufacturer has approved. Will last five or more years before your next AF change. The difference in price per gallon is more than paid back in useful life of the AF.

Thanks everyone! I'll try to drain and flush it this weekend with fresh water and see how it comes out. I'll keep you posted.

Thanks again!

I'll try to drain and flush it this weekend with fresh water and see how it comes out.

The gunk sticks to all the interior surfaces , some type of cleanser is required , the 2 part do best.

Hi Everyone,
Just a note of thanks! Flushed the coolant six times, the third and fourth with radiator flush. Lots of stuff came out, but the system is now very clean and running well.
Thanks!

Were you able to determine how long the stuff had been in there?

Glad it was nothing major!

I have no idea how long the coolant has been in there. I just purchased the boat, a 36' Marine Trader. The generator was installed new in 2009. By the condition of the AF, I'm guessing it's original.

If you ever have to do something like that again use Cascade dish washer detergent. That is what most/many mechanics use to flush a cooling system out with. It's a fairly strong non-foaming detergent that does a great job of cleaning out old or contaminated fresh water cooling systems.

Cascade dish washer detergent.

This is just TSP, the feds could regulate soap ,for washing stuff, but none dared to get in the way of the ladys dishwasher lobby.

TSP ?? whats that I thought... for the others who didnt know the acronym !!
Using TSP (Trisodium Phosphate) as a cleaning product