QuestionHi, I have a 1991 Porsche 944 S2 and I have a question about the coolant system. The level is a little low and on testing the coolant, it is poor so I need to drain and re-fill the coolant system. However, on opening the coolant container in the engine (when checking the fluid) I noticed some black/dark gray sludge on the inside of the container. The fluid itself seemed OK, but I am concerned that when I re-fill the container up to its max level, the sludge will come off the sides and into the fluid. I have checked all of the other levels in the car (oil, brake fluid etc) and there is no evidence of this sludge in anything else. My question then is should I try to remove this sludge before re-filling the system and if so, how? Or am I worrying about nothing.
THanks for your time!
AnswerHoping the sludge is not oil.
In answer to your last question "should I try to remove this sludge before re-filling the system and if so, how?"
Yes. You can flush the system using common coolant flush before you refill. Lot's of retail products at the big box stores to choose from.
Are you worrying about nothing? Well, it depends upon what the sludge is or what caused it. Is it oil in the system?
I would want to remove the sludge because the sludge can form a thin insulator which would reduce cooling performance.
So, flush, flush, flush. Wash clear with fresh water.
Refill with a non phosphate favorite brand.
And, watch over the next few months to see if "new" sludge reappears.
