Thread: Sludge in Coolant

You may just need a coolant flush if youve never had one done. Air can cause it to sludge or mixing it will too. As for the LIM yest thats Lower Intake Manifold gasket and as far as difficulty I dont think it would be terrible just time consuming. Ther is probably a writeup someplace here.

you need a coolant flush, its the dex coolant sludging up.

lim gaskets are pretty easy, search youtube for lifters in 33 minutes, it covers most of the job. and then theres plenty of threads here that cover parts lists and such.

you can switch to green coolant, and end the sludge issue.

the lim gaskets should be done on general principals really. they are failing as we speak.

if you do the job yourself and shop smart, you can get it done for around a 120 in parts or so.

you'll need the lim gaskets, the upper plenum gasket, coolant elbows, a oil change, and a 1 gallon of antifreeze. and some thread sealant for the lim bolts.

Originally Posted by 1quick

the 04 gtp should have metal lim gaskets they dont fall apart like the plastic ones did, i would flush the dex crap out of it tho and switch to green

hes got a good chance of having plastic gaskets from the factory, every 04 ive seen here has had plastic lim gaskets. GM must have been using up old stock for a few years.

Ok well let me clear this up, you guys seem to be leaning towards the LIM gaskets failing causing this sludge on just a hunch, when many things can cause it. It could possibly be the cause, but more likely someone mixed the wrong coolant, or there was air in the system for a long time.

First check to see what gaskets you have. Most of the time you end up with the plastic gaskets that will fail since they didn't put them in til mid 05, but if you aren't the original owner you never know if they were replaced with aluminum gaskets before you bought it. Mine were.

Then make sure there is no coolant in your oil, and that you aren't loosing coolant, the overflow level should be where it needs to be. If it is, the gaskets aren't leaking...yet, if they're the plastic ones. If this is the case there was either air in the system or someone mixed coolants. If there's a lot of sludge someone probably mixed, but if there's just a little bit floating or some on the cap air is probably the cause and a flush is the solution. I would flush completely with water getting all of the old stuff out, then refiling with conventional green. Dexcool does it's job but is way too picky.

Also you asked is there a way to make sure the radiator isn't failing letting oil in the coolant. You can just check the trans fluid and make sure that coolant isn't in the trans, and also make sure the level is where it's supposed to be.

these will work. i used the acdelco set myself. look for some discount codes as well.

this is off the rockauto site. for a 04 like you have.

ACDELCO Part # 89017825 GASKET KIT,INT MANIF	$44.79

the set i installed on my car.



the old plastic gaskets, see the smaller ports, how they are deformed and some what blown out. thats the failure.

Originally Posted by 02NavyBlue

Ok well let me clear this up, you guys seem to be leaning towards the LIM gaskets failing causing this sludge on just a hunch, when many things can cause it. It could possibly be the cause, but more likely someone mixed the wrong coolant, or there was air in the system for a long time.

First check to see what gaskets you have. Most of the time you end up with the plastic gaskets that will fail since they didn't put them in til mid 05, but if you aren't the original owner you never know if they were replaced with aluminum gaskets before you bought it. Mine were.

Then make sure there is no coolant in your oil, and that you aren't loosing coolant, the overflow level should be where it needs to be. If it is, the gaskets aren't leaking...yet, if they're the plastic ones. If this is the case there was either air in the system or someone mixed coolants. If there's a lot of sludge someone probably mixed, but if there's just a little bit floating or some on the cap air is probably the cause and a flush is the solution. I would flush completely with water getting all of the old stuff out, then refiling with conventional green. Dexcool does it's job but is way too picky.

no one said bad lim gaskets caused the sludge, they should be changed as part of the engines new owner maintenance, along with all the other tune up related crap one does when they buy a used car.


dex does sludge up for all the reasons you stated tho, air or mixing of coolants being the biggest culprits.

if you look between the head, and the lower intake, you can see the gasket, if you see black, its the old crap, silver, and its been upgraded already and can be left alone.

Right, it's good that you guys encourage changing the gaskets as a preventative thing, but at least make sure the OP knows that's why you're encouraging it, not because we think that's the solution to this thread's problem. It wasn't exactly worded that way but it comes across.

He said the coolant is actually brown, that's usually due to mixing coolants. If it's still red/orange with a bit of sludge at the top it's from air.