Thread: Coolant sludging after 2 flushes

Hey y'all so I'm wondering about my 04 gtp comp g and what's going on to cause sludge buildup on the radiator cap even after 2 good flushes with the hose? When I first got the car a few weeks ago it was really bad almost like the coolant had never been changed, so I flushed and got it clean or so I thought. Did another flush and was clean at the radiator and heater hoses, and shortly after im still noticing build up at the bottom of my radiator cap. Changed upper and lower hoses already too. Is this the LIM gasket failing issue or is my engine just that sludged up with coolant or is it something else? What do you guys think I should do?

Yea just used water only with a hose.. guess that wasn't good enough and I should do it again with a flush treatment? Some people had originally told me not to use them for some reason

Yea went with a new reservoir since mine was so dirty
I'll prob do another flush with the treatment and report back. Just wondering if it's a more serious problem like lower intake manifold gasket fail like on the older 3800s

Do you have oil in your coolant or are we talking old nasty dexcool exposed to air sludge?

Draining the system, refilling with water and healthy about of dishwasher detergent and then running for about 30 minutes, repeating several times, is the only thing that works in my experience. Afterwards you have to replace your hoses and coolant reservoir. Oh, amd make sure the heat is running while doing this!

Hey thanks for the reply...so I don't believe it's oil as it's not milkshake like, my buddy said it's rust which seems believable...car runs fine and doesn't overheat.. I plan on doing some more flushing soon. Bought a bottle of that prestone system flush...won't that work well too or is this stuff not recommend for some reason??
And and I'm really supposed to remove the tstat while doing this? Won't that help with the process by building up heat first then opening to get a good flush or does it not matter? I always remove the tstat for a garden hose type flush but everything I've seen when letting car idle and drain, repeat, doesn't mention removing tstat...

Hey thanks for replying...so I should pull tstat for this type of flush? Adding just water with a cleaner and running the drain? Or do you mean pull tstat when doing the garden hose type flush?

Hey guys so I ended up doing a couple flushes yesterday, pulled the tstat and used distilled water with a flush treatment. Was working my 3rd one just now and all the sudden after idling / small drive for like 10 minutes and turning car off, I heard some horrid noise and my reservoir started overflowing like crazy. I didn't overheat and never have so I'm worried about this. Any ideas here? Is this a head gasket fail? Or a clog somewhere?

Originally Posted by tomsteve

and pull the tstat,too.

Yes, also important. And I'll add that the hose replacement is only necessary if you have oil in the coolantnor the coolant is so bad that it's leaving behind sludge and degrading the hoses. You can never get them clean and once they experience this they're weakened.