Radiator Sludge

[Sacaledus]

I have some black/grayish sludge accumulating in my overflow tank and on the radiator cap. Where's it coming from, how bad is it, and how do I begin to track it down to fix it? As always any and all help is much appreciated!

[MKMike]

Has the antifreeze been changed within the past 1-4 years?
If not, clean the residue out of the reserve tank and off the cap, then drain the entire cooling system and refill it with new antifreeze mixture.
When antifreeze loses its anti-corrosion properties, it allows the expensive parts it comes in contact with to oxidize.
Most people don't realize that the anticorrosion chemicals are a very important part of your antifreeze.
Read more here: http://www.aa1car.com/library/cooling_s ... rosion.htm

While you can do the tests they detail, it's probably faster and easier to just drain and replace the antifreeze--including the mucky antifreeze in your overflow tank.
A 50% antifreeze/50% water mixture is best.
You can even buy it premixed.
This may also be of use to you http://www.pontiacbonnevilleclub.com/fo ... ic159.html

[1oldman]

I'm definitely with MKMike. Be sure and use distilled water, not tap water. Tap water has minerals in it. The minerals can build up in the heater care and radiator. You just might have a failed LIM gasket too. Be sure and investigate that while you are "at it". - BC

[Hotwheels]

Agreed, doing a coolant flush is a needed and often overlooked piece of routine maintenance, just like changing oil or diff fluid or any other fluid. Like it was said, a lot of people forget that coolant is not just about the cooling part of things but also the anti-corrosion part of things.

[Sacaledus]

Will get that done and check back with the results! Thanks all!