brown sludge in radiator with green coolant

[Sixxshot87]

the coolant in my car is as green as new but if i run my finger around the inside of my radiator when i take the cap off i get a brown sludge? what is this stuff. I have a new ron davis radiator and not the stock well used one help. Car runs rough and im currently getting the fuel injectors cleaned and tested. Again the coolant is as green as new.

 

[notacarlo]

Looks like rust and oxidation after 24 years of use. Sometimes people put bars stopleak in their radiator, after many years that is waht the residue looks like.

 

[DailyDrifter]

Its either BARS leak stop residue, or lack of maintenance. I've seen GM cars and trucks that turn dexcool into mud. Its a bitch to try and flush out. It's normal though for dexcool.

 

[groumoutis]

I had that crap in mine too. I took about a month straight of flushing driving then flushing again. It was so bad when I bought it that the lower half of the radiator was clogged. My temps were around 210 with a 160 stat. After a lot and I mean a lot of flushing I got it running at 175 on a 90 degree day in city driving. That is with the factory radiator and fan. I did have to take out the radiator and boiled it out with a water/ muriatic acid mix. I left it in there for 25 minutes and flushed it out after for about half an hour with the garden hose.

I ran the car on straight water for a few hours of driving time and flushed it out again with the hose. Like I said it dropped the temps 35 degrees. Just be very carefully with the acid. The stuff I used was 31% acid and I cut the acid in half with water. Don't do this around a concrete driveway! The acid is used to etch concrete.

 

[charlief1]

What you have is silca fall out. This is normal with the original green anti-freeze. It has silica in it to prevent rust but as it gets older it falls out of suspension and looks like what you posted.