oil(?) in coolant reservoir

**knoll5150** · 10-17-2008, 03:16 PM

Have a problem that seems to even baffle the local mechanics I talk to on this. Hope someone out there has an idea. Earlier this spring, had a mechanic notice an oily sludge, mixed in with the coolant on the dipstick going into the coolant reservoir. Had the coolant changed, to flush the crap out. Was fine through this summer, but when I checked the coolant dipstick, a week ago, I noticed the same sludge.
Weird thing is, it only seems to be in the reservoir (fill) tank, but if you pop the radiator cap next to it, the coolant is completely clean. Mentioned this to another mechanic and he thought it could be a blown head gasket. Thing is, the car runs and idles great, their are no leaks in antifreeze or oil (on the ground), no overheating problems, and starts up fine everytime. Only issue I can think is that sometimes I'll get a loud "pop" coming from the exhaust. Usually just when I give it alot of gas, shifting through gears. This only happens at initial startups, and immediately goes away. Not sure if that's just the way the exhaust is (SLP "loudmouth") or backfiring. Sorry to ramble on, just hope someone has a thought on this.

**Wesman** · 10-17-2008, 04:19 PM

It almost has to be a headgasket issue, because LS motors don't have any coolant passages in the intake manifold that would allow coolant to seep into the oil system. So the only possible source is the head gaskets.

How long have you owned the car?? Chances are it was overheated at some point in its life, causing one of both of the head gaskets to become damaged and start to leak. Generally LS1 head gasket issues are rare, because the head bolts are very strong since they pull from the bottom of the block. However, overheating will ruin any head gasket and cause it to leak.

Since you will have to pull the heads anyway, it would be a great time to upgrade to some better heads, even just a set of LS6 heads and a matched cam would give you a nice 60HP jump in power over stock, and driveability and fuel economy would be the same as stock

**knoll5150** · 10-17-2008, 04:52 PM

I've owned this car for a year and a half. Again, most people I talk to say "bad head gasket", because of the oil mixed with the coolant...but the weird thing is I'm not getting the usual symptoms you mention... i.e. overheating, leaks, etc. Car runs great...just bothers me having the gunk in the coolant reservoir. I dunno, maybe I should just let it go.

**knoll5150** · 10-17-2008, 04:56 PM

p.s. sweet Burt Reynolds pic...was that Stroker Ace or Canonball Run?

**RAWPWR3** · 10-17-2008, 06:23 PM

Originally Posted by knoll5150

I've owned this car for a year and a half. Again, most people I talk to say "bad head gasket", because of the oil mixed with the coolant...but the weird thing is I'm not getting the usual symptoms you mention... i.e. overheating, leaks, etc. Car runs great...just bothers me having the gunk in the coolant reservoir. I dunno, maybe I should just let it go.

First, lets try and find out a little more info about whats going on. What type of coolant was in it before the flush and what type did you put in? When youre mechanic flushed the system, did he also flush the reservoir tank? This is often overlooked during a flush, and since you say you dont have the typical symptoms of a leaking head gasket, and especially since the fluid in the radiator is still clean, im thinking its just old gummy dex cool that was left over in the overflow tank.

**alexa** · 10-17-2008, 10:05 PM

Had the same problem - gunk in overflow tank. I flushed the system, believe previous owner never did it before. Also changed power steering cooler thought that might be a cause.Some gunk returned in a week but much less this time. Flushed the second time - paid lots of attention to overflow tank it's not easy to get all the oily substance out of there. I took it off and rinsed 100 times with very hot water until clean water started coming out, without that ugly oily film on surface. Put it back - now it's been a month and I got only trace of oil, I guess it's been washing out from block since I never drained the block itself. Gonna flush it again, hope this time will get it cleaned out completely. BTW car was running without any problems - not a single indication of blown head gasket but gunk in coolant.
Run oil analisys,it'll tell you for sure what is that - may be it's not engine oil but power steering fluid, since you SS got PS cooler. Do you lose PS fluid? Or if Dexcool wasn't flushed for a long time it tends to leave that kind of gunk in the tank which is not that easy to remove. There are some posts regarding that issue: you have to flush it regularly.
Hope this helps

**Sarge** · 10-18-2008, 05:08 AM

You may have left DexCool in too long. On your dipstick is there any milky looking "stuff"? If not you need to flush and fill a few times to get the brown milkshake crap out of your cooling system.

**0rion** · 10-18-2008, 07:11 AM

I agree with what a these guys are saying. Dexcool itself will sludge up. Can you describe the stuff in your reservoir a little better? That reservoir is pretty easy to take off the car. Remove the battery and it's only 1 or 2 bolts that hold it on there. Pull it off and clean it out real good.

**knoll5150** · 10-18-2008, 07:27 AM

The substance is kind of "milky" like you guys mentioned. And I did switch from Dexcool to the green stuff when this all started (I know, I know, should have kept the Dexcool). How do you guys flush out the reservoir without messing with the entire system? Just pull the top (or bottom) hose going into the radiator then spray the crap out of the reservoir? Thanks!

**alexa** · 10-18-2008, 08:52 AM

Originally Posted by knoll5150

The substance is kind of "milky" like you guys mentioned. And I did switch from Dexcool to the green stuff when this all started (I know, I know, should have kept the Dexcool). How do you guys flush out the reservoir without messing with the entire system? Just pull the top (or bottom) hose going into the radiator then spray the crap out of the reservoir? Thanks!

Take the reservoir out. Thats not hard.Just 2 bolts as Orion mentioned and you lift it right out. There is no bottom hose, just one going to the neck of rad. To my mind you won't be able to flush that tank really thorough without taking it off.

**0rion** · 10-18-2008, 09:08 AM

Originally Posted by knoll5150

The substance is kind of "milky" like you guys mentioned. And I did switch from Dexcool to the green stuff when this all started (I know, I know, should have kept the Dexcool). How do you guys flush out the reservoir without messing with the entire system? Just pull the top (or bottom) hose going into the radiator then spray the crap out of the reservoir? Thanks!

did you flush the dexcool really well before switching? I think we've found the root of your problems. You need to powerflush you're whole system. Perhaps they did powerflush it and it didn't get the reservoir clean but it's not something you want to screw with. Not sure if you've ever seen what happens over time when you mix regular glycol with dexcool but it gets nasty and will plug up your heater core among other things. Someone topped my truck off with green coolant at some point. I have to back flush the heater core every year and when I pulled the intake to do a gasket 2 years ago the stuff had turned to a crayon consistency on the back ports of the intake. You want to make damn sure you've gotten all the dexcool out of there before running regular glycol.

**"B4C"** · 10-21-2008, 09:17 AM

I may be way out of line here , but my son and i had sludge getting in the overflow and it was powersteering fluid from the cooler in top rad hose. cooler had gone bad. not installed on all cars but was on ours (b4c and ss)

**0rion** · 10-21-2008, 10:30 AM

Originally Posted by "B4C"

I may be way out of line here , but my son and i had sludge getting in the overflow and it was powersteering fluid from the cooler in top rad hose. cooler had gone bad. not installed on all cars but was on ours (b4c and ss)

that's a thought. I had actually thought about that but he says his fluid in the radiator is clean which is why I steered away from the ps cooler. I would think that would sludge up everything. After he said he switched coolant types that would almost be my bet, the 2 mixed a little in that overflow due to it not getting flushed out of there. I could be wrong though.

**Firebirdjones** · 10-21-2008, 04:19 PM

Originally Posted by knoll5150

p.s. sweet Burt Reynolds pic...was that Stroker Ace or Canonball Run?

Thats Smokey and the Bandit

**Wesman** · 10-21-2008, 05:44 PM

Originally Posted by knoll5150

p.s. sweet Burt Reynolds pic...was that Stroker Ace or Canonball Run?

Originally Posted by Firebirdjones

Thats Smokey and the Bandit

Yep

**kryptoniteSS** · 07-02-2009, 01:39 AM

Originally Posted by "B4C"

I may be way out of line here , but my son and i had sludge getting in the overflow and it was powersteering fluid from the cooler in top rad hose. cooler had gone bad. not installed on all cars but was on ours (b4c and ss)

i agree with b4c im going through the same problem, power sterring cooler is what's wrong it made water go in the power steering pump and yet my radiator shows no sign of oil, i would check that before replacing anything more expensive.

**TA98** · 07-02-2009, 08:11 AM

Head gasket. The reason the oil in only in the tank is because oil is lighter than water. the oil get pushed out first when the engine gets to hot since it is on top, reason for it being in the tank only.

**flipsutter** · 07-02-2009, 12:01 PM

I went home at lunch today and took the coolant overflow out and sure enough I have the same thing. Its caked with this brown milky crap. I spent 30 minutes trying to wash it out. It never did all come out. I guess I'm going to have to find something to brush it out with. I have been losing power steering fluid for the past month and I couldn't find the leak. I bet its getting into the coolant. Great.......

I also checked my dipstick and I don't have that milky substance on it. So I don't think its a head gasket issue.
This car is killing me...

b.t.w. Bad ass movie. I watched it again this weekend.

**TA98** · 07-02-2009, 02:41 PM

I dont think that your power steering fluid and engine coolant should ever even be able to mix like that so i dont think thats where the fluid is going.

**99RTA** · 07-06-2009, 10:04 AM

What you have is called DEX Sludge.....once it has started its very hard to stop. The brown sludge you are seeing is actually the aluminum in the engine that the dexcool has eatten away at. Dexcool can turn into a very strong acid in the presence of air. Either you are running a little low on coolant or its not been changed soon enough.

NOW THE BITCH PART. my 99TA started having the EXACT same trouble at about 30k miles. I tried to stop it by flushing and changing the dexcool but it never stopped. The sludge just came back into the coolant resivor. I contacted Prestone and they told me all the garbage from system collects in the coolant resiovor because it is the coolest part of the system. Car still had the sludge in the tank at 134k miles when i sold it. Even though i flushed it evey year. Once dexcool starts its eatting good luck stopping it.

Now my 02 Formula with only 31k miles on it looks good with no signs of sludge. Wish i knew why some cars do it and others don't but i suspect its most likely from running a long time with low coolant and a poor sealing - operating rad cap.

DEXCOOL IS GARBAGE!