2000 GT - Oil in Coolant Reservoir??

[jbeltz7]

Several months ago I had my cooling system flushed and the factory technician said my manifold was leaking and needed to be repaired costing several hundred dollars. Since I haven’t been loosing any oil I figured it was unnecessary and just had them change the coolant and reservoir. Recently I found what definitely appears like oil in the coolant reservoir, not allot just a greasy film sticking to the sides and cap. Searching these forums I found several discussions about intake manifold leaks but none that mentioned my problem. I would hate to go through all the work to regasket the intake only to find my problem was elsewhere. The 3400 engine has 115,000 miles. TIA

[pcprophet]

when coolant mixes with the oil it should turn into a milky subtance, engine overheating, check your oil cap to see if you see a mily subtance. since you had a system flush is shouldnt be any sludge build up anymore unless they didnt clean out the reservoir, is it just around the caps.

you should get some pictures up so to what it really looks like.

hopefully some one else with help you out, just going through what i would of checked for.

[Brad97GS]

I don't want to tell you 100%, as I don't have the same engine, but...

I had oil in the coolant with my Riviera this past summer. Replaced the intake manifold gasket, changed the coolant, and everything was fixed. :)

BTW, I definitely had oil in the coolant, but there was no coolant in the oil (at least visibly). Therefore, I never had any milky substance around the oil cap.

[rixGAphx]

3400 engine /115,000 miles.
Originally posted by jbeltz7
Several months ago I had my cooling system flushed and the factory technician said my manifold was leaking and needed to be repaired costing several hundred dollars.
Since I haven’t been loosing any oil I figured it was unnecessary and just had them change the coolant and reservoir.

It might have been a 'dealer mechanic, factory-trained', but I'm sure you weren't dealing with a 'factory technician' (a highly-trained and fully-authorized person, literally from the factory, sent into the field to deal with a particularly nasty customer-relations issue).

Nearly EVERY trained mechanic can look at ANY '94-'03 GM 60*V-6 and honestly say, "The gasket on the Lower Intake Manifold is leaking, and needs replacing for about $650US."
S/He may have been 100% correct; why didn't you trust his/her judgement and recommendation at that time?

My next question to you is, Why were you having them look at your car to begin with?
* Symptoms?
* Regular maintenance?
And, why did they replace the coolant reservoir? Sometimes they crack, was this your case?

Losing oil is NOT sign of failing LIM gasket.
Losing COOLANT is a sign of LIM gasket failure (among other things).

When the LIM gasket leaks, the coolant flows out of the LIM-to-head passages.
* If it flows outward, it dribbles down the ends of the heads and leaves 'tear-stains'.
* If it flows inward, it drips down into the crankcase oil.
But the oil can't drip UP and into the pressurized coolant system.

Recently I found what definitely appears like oil in the coolant reservoir, not allot just a greasy film sticking to the sides and cap.
Though not 'normal', a very slight film of oil on top of the coolant isn't unusual for any engine, and it is no more a cause for alarm with our V6's than with any other engine.

Did they replace any heater or radiator hoses?
My *guess* would be that a little oil or grease, used for lubricating the hose ends during attachment, has contaminated the water-based coolant.

'Suck' the oil scum off the top of the coolant, and wipe-down the sides of the reservoir as best your fingers can reach.
Use a clean, dry cloth towel (or 'Handi-Wipe', the superstrong paper towel that won't tear and leave debris in the coolant).

Searching these forums I found several discussions about intake manifold leaks but none that mentioned my problem.
I would hate to go through all the work to regasket the intake only to find my problem was elsewhere. What's your problem/symptom?

If you mean the oil scum in the reservoir, just clean it and check in another week.
I'll bet it never returns, and you should not be concerned.

If oil continues to appear in the oil, then serious investigation is necessary.
But the problem will NOT be caused by a LIM gasket failure, since there is NO oil flowing thru the LIM (or its gasket).
Only coolant, and intake air, flows thru the LIM.

But, all this ^^^ doesn't mean that your mechanic wasn't accurate that you needed a LIM gasket replacement.

I think you need to go back to your 'search', and check your engine for the indicated symptoms signs of LIM gasket failure.

Good luck,
-Rick

PS:
I don't know why Brad's Riviera had some oil in the coolant, nor why an IM gasket change solved the problem.
But I'm pretty sure the Riviera doesn't have a 60*V6, so the point is moot.
Our engines behave differently than other V6's :roll:

[jbeltz7]

Thanks for the replies, here is a pic of the gunk in my coolant system. This has occured in the last couple months, since the new bottle and flush.

Took it in for a flush and fill as standard 100k maintainance. Never saw any coolant leaks and mabye put a half-gallon of coolant in the 5 yrs my wife had been driving it.

The original bottle was so discolored it was difficult to determine the correct level so I replaced it. There was also this same gunk in the old bottle but I just figured it was due too the "new" type antifreeze.

"Nearly EVERY trained mechanic can look at ANY '94-'03 GM 60*V-6 and honestly say, "The gasket on the Lower Intake Manifold is leaking, and needs replacing for about $650US."
S/He may have been 100% correct; why didn't you trust his/her judgement and recommendation at that time"

The "NEARLY" and the "$650".
Also as you mentioned it makes no sense for a leaking intake to result in oil in the coolant. Doesn't set well but since the car runs great I probably will just drive it until I start getting some more definitive symptoms.

[bballr4567]

Yea that looks like a LIM gasket failure. I got the same problem. No coolant in the oil but oil in teh coolant.

EDIT: Sorry I was wrong. Disregard above info.

Also by oil in the coolant I mean the tiny amount that makes a lil slick on top.

[HeyDace]

"Nearly EVERY trained mechanic can look at ANY '94-'03 GM 60*V-6 and honestly say, "The gasket on the Lower Intake Manifold is leaking, and needs replacing for about $650US."
S/He may have been 100% correct; why didn't you trust his/her judgement and recommendation at that time?"

You would think so, wouldn't you? I had a customer the other day that had the LIM leak...the dealer "Tech" tried selling her a radiator.

:roll2:

[Brad97GS]

Originally posted by rixGAphx
PS:
I don't know why Brad's Riviera had some oil in the coolant, nor why an IM gasket change solved the problem.
But I'm pretty sure the Riviera doesn't have a 60*V6, so the point is moot.
Our engines behave differently than other V6's :roll:

Yeah, it's a 90 degree V6 - obviously a different setup, but I posted it just in case it would be helpful.

[rixGAphx]

Originally posted by bballr4567
Yea, that looks like a LIM gasket failure.
I got the same problem.
No coolant in the oil but oil in teh coolant.
NO, that does NOT look like a LIM gasket failure.

What don't you understand??
Oil in the coolant is NOT a symptom of LIM gasket failure in the GM 3.1/3.4.

Oil in the coolant, large amount or small, does NOT result from
LIM gasket failure.
It just doesn't.

[bballr4567]

Originally posted by rixGAphx
NO, that does NOT look like a LIM gasket failure.

What don't you understand??
Oil in the coolant is NOT a symptom of LIM gasket failure in the GM 3.1/3.4.

Oil in the coolant, large amount or small, does NOT result from
LIM gasket failure.
It just doesn't. Well I was told by a mechinac that the peanut butter mixture on the coolant tank lid is a good indicator of LIM failure. Sorry if I was wrong but I was going off what I was told.

[Tommy00GT1]

Actually, I wish somebody could positively list any/all symptoms of LIM failure. I know it would help out quite a few people; myself included.
We seem to have conflicting opinions... anyone know with 100% certainty?

[1CoopGT03]

Usually the milky color that your all talking about in the oil or the coolant reservoir indicates a blown head gasket maybe LIM gasket . The pic he posted is not milky on that cap. That looks more like somebody possibly mixed in regular antifreeze with the Dexcool or old Dexcool . Who ever flushed the system may not have cleaned the reservoir & the cap. I seem to remember reading somewhere that if air is trapped in the cooling system it can also cause the rusty colored goo that's shown on that cap.

[Ross86]

I just noticed the same thing with my 3.4. I was going to replace the thermostat sensor and noticed some extra oil around the LIM. But if the LIM and radiator have nothing to do with each other, then I'm stumped. The oil on the engine probably has something to do with the fact that I changed to a synthetic oil about 6,000 miles ago. But there is that same stuff all over the bottom of coolant lid. I noticed a significant amount in the reservoir too. I'm 95% sure it's oil because of the way it looks and it isn't mixing with the coolant. I do all of the maintenance on my car and this stuff wasn't in the resevoir until recently. Didn't mix different types of antifreeze either.

[rixGAphx]

Originally posted by Ross86
I was going to replace the thermostat sensor There's a thermostat, and there's a 'Coolant Temperature Sensor'; but there's no "thermostat sensor".

Which are you going to replace?
What are the symptoms?
...and noticed some extra oil around the LIM. Well, all oil on the outside of the engine would be 'extra', since the oil should only be inside.
Where precisely do you see this oil, relative to the LIM or one of the LIM gaskets?
But if the LIM and radiator have nothing to do with each other...Nobody ever said this; well, not in this thread, anyway. :confused:
The engine coolant flows through BOTH the LIM and the radiator, so they DO have 'something' to do with each other.

The discussion has been that OIL does not flow thru the LIM, and therefore that oil in the coolant system has nothing to do with LIM gasket failure.

-Rick

[Ross86]

Last week my Service Engine light came on. I took it to...Auto Zone and the guy checked the code and said something to the effect that my car was running too cool and he said that either my sensor was bad or the thermostat was stuck open. The light went off before I had the chance to replace either.. today was the first chance I had to take a look at it. That's why I was messing around under the hood. I know it doesn't make sense to replace BOTH parts, but my dad bought the parts & is making me replace them.

Sorry I misread the part about the relationship between the coolant, LIM, and oil.

The engine oil was as far as I could tell behind the (front) exhaust manifold on the block. In that area. It's dark outside and I don't have a flashlight. I know they changed the gaskets used on the manifold(s) around 2003. Would mine be the new or old gasket?

I've been searching on the net and I haven't found much about the oil in coolant problem..except that it has happened to other people.

Sorry if I used the incorrect terminology anywhere.

[Ross86]

Not my car, but this is the gasket that oil is leaking from. (Thanks to Kelly for the pic). It is leaking on both sides. I circled/squared the area near the bottom of the picture in white.

[rixGAphx]

Originally posted by Ross86
...Service Engine light came on.
...Auto Zone and the guy checked the code and said something to the effect that my car was running too cool and he said that either my sensor was bad or the thermostat was stuck open. The light went off before I had the chance to replace either...
...but my dad bought the parts & is making me replace them.
1. Go to AZ/Checker/O'Reilly's/etc. to get the Diagnostic Trouble Codes (DTC's) scanned, then write down the code numbers and report to us for advice.
2. The DTC's indicate problems in systems and circuits, not which parts need to be replaced.
The NAPA parts people are highly-trained, but even they are not automotive mechanics. AZ/Checker counter people are mainly trained to sell parts; do NOT take their advice based just on a DTC.
3. Even when the SES light goes 'out', the data that caused it to go 'on' is retained for 30 on-off cycles of the ignition key.
You can take the car back to AZ and get the codes checked a week later, if you only drove the car twice a day (4 'starts' x 7 days = 28 cycles).
Unless the technician who scanned the codes deliberately erased the code with the scanner, which many do.
4. When the light goes 'out', the problem has GONE AWAY. Period.
No need to replace anything, since there's no longer anything wrong.

The t-stat *might* have stuck open ONCE, setting the code; and the t-stat *might* be failing or it might never do it again.
The T-stat is very difficult to get to on the V6, so I wouldn't touch it at this time.
5. Parts bought by dad = teh WIN!! :D :D

The engine oil was as far as I could tell behind the (front) exhaust manifold on the block. In that area.
The LIM, and its gaskets, are in the 'V' ov the engine.
The gaskets extend to the ends of the heads, and are prone to leak coolant at those ends if the gasket fails.
LIM gasket failure has NOTHING to do with the front or rear of the block (or the heads).

If you have oil down 'the front of the block', it's from either:
* A little spillage while filling the oil at the cap in the valve cover; or,
* The rubber gasket under the valve cover, where it attaches to the head.

Farther down the block is the oil filter.
Sometimes that isn't well-tightened by the technician who replaces it during an oil change, and it may leak a little past its rubber seal.
I know they changed the gaskets used on the manifold(s) around 2003.
Would mine be the new or old gasket?
I dunno, sorry.

I've been searching on the net and I haven't found much about the oil in coolant problem..except that it has happened to other people.
You haven't found much because it isn't 'a problem.'

As I said originally, it's not unusual for there to be a *little* oil on the coolant surface, and a little scummy-looking crud on the underside of the cap.
It's not an indication of ANYTHING.
It just happens, kinda like cheese in the refrigerator will eventually get a little mold on it (from spores in the air); clean it off and get on with life.

There is only one way that the coolant system on a modern car can get a significant amount of oil in it: If the tranny cooling line (running thru the side tank of the radiator) splits inside the tank and dumps tranny fluid into the coolant.
I've never heard of this happening on a GA.
So it's extremely rare.
And you'll never get a HINT of it in advance, it will just blow all at once and your tranny will stop and all sorts of expensive bad things will result.
You are more likely to win the Powerball, and then you can buy a Ferrari, than this will EVER happen. :roll:

Worry about world peace, not oil in the coolant. :D

Good luck,
-Rick

[rixGAphx]

Originally posted by Ross86
Not my car, but this is the gasket that oil is leaking from. (Thanks to Kelly for the pic). It is leaking on both sides. I circled/squared the area near the bottom of the picture in white. Well, that black line is the gasket.
It's between the LIM (above, spanning across the 'V') and the cylinder head (below).

If the stuff you see/touch there is oily, prolly with a little ultra fine dust in it, then that is kinda *normal* for an engine that hasn't been washed with a toothbrush every weekend like Kelly's :D :D
* Usually, the oil is actually oil vapor, prolly from the washer around the PCV valve or the oil filler cap.
It doesn't 'leak' to that location, but rather condenses out of the air. And dust in the air sticks to it.
* There might be a leak in the valve cover gasket, allowing oil to drip out; but that's not a typical location for a valve cover gasket leak.

If what you see/touch there isn't oily, but rather a hard brownish stain (kinda like the tear stains under the eyes of a poodle or cocker spaniel), then that is the dried residue of leaking coolant (which can have a slightly oily feel when wet) from a failed LIM gasket.

Hope this helps,
-Rick

[1CoopGT03]

When my LIM started leaking that was where it leaked from. Circled in that pic. Mine was leaking Anti freeze on both ends of the engine same spots. Mine's a 2003 also .

[RocketFast321]

Originally posted by Tommy00GT1
Actually, I wish somebody could positively list any/all symptoms of LIM failure. I know it would help out quite a few people; myself included.
We seem to have conflicting opinions... anyone know with 100% certainty?

disappearing coolant is the main thing

[Ross86]

Thanks guys. The car is under warranty for 20,000 more miles. I'm at 76,000 right now. I think I will clean up the engine and do a radiator flush. If anything happens later on or if that oil reappears around the gasket, then I will just take it to the dealership & let them work on it. I am going to be putting about 500 miles on it this weekend, so that's why I was concerned. Thanks again for the info/explanations.

[Tommy00GT1]

I'm under warranty too Ross.... That's why I wish I knew how to speed the damn thing up so it can be replaced under warranty.
Maybe I should take the car down the Mass Turnpike and redline it, lol......