Thread: dirty coolant

a coolent flush will fix..just old coolent that got broken down over time and turned brown

is it all brown and sluggy?.. and whats the bottom of the radator cap look like?

yea it just need to be changed out, has the coolent ever been changed?

If someone owned the car before you they could have had a coolant leak and put radiator sealent in. This will eventually turn brown and sluggy like you are describing. Not sure how long you have owned it though. Either way a coolant flush wouldnt hurt!

Originally Posted by Curt7

radiator sealent

Unlikely, as his description is a dead-ringer for bad Dexcool. Your car was low on coolant at some point or has a leak, which caused air to get into the cooling system. This air reacted with the iron, created iron oxide, and that reacted with the Dexcool to make an Old Bay Seasoning kind of sludge.

Since your GP is a 2004, you have a nylon lower intake manifold (LIM) gasket. Starting in 2005, GM began using aluminum lower intake manifold gaskets because the nylon ones were faulty - they would melt and crack, allowing oil into the coolant and coolant into the oil (coolant in your oil is a very bad thing). By 120,000 miles, you definitely need the aluminum gasket.

There are plenty of threads on the subject; just use the search function. There's even a video on how to do it yourself - otherwise, most shops will bill the job as 6-8 hours of work, plus parts.