Thread: '00 GT Losing oil and coolant + overheating

Hi everyone,

I have an issue with my 00 GT. I have noticed that is is losing oil at a rate of about a quart a month plus is loses coolant at the same rate or a little faster. The car runs well, but I have noticed now that it is getting warm that if I am not moving or moving in slow traffic and have the AC on then the car will get very hot (220-240 before I shut the AC off). Turning the AC off and rolling down the windows keeps the car from getting too hot. I have flushed the coolant last summer and ran it with water several times, flushed, ran with water, flushed, etc. to try to get any of the dexcool out of the system. I now have 50/50 regular coolant water mix and I am still having overheating issues. I do notice the smell of burning coolant when I shut off the car sometimes, and it appears that coolant is weeping onto the heads (both) on both ends of the motor. My thought is LIM gaskets probably need replacing but would that account for the oil loss too? There is never a drop of coolant or oil under the car even after parking for several days. Other than the coolant that appears to be on the heads of the motor I do not see any other leaks of coolant or oil. Any help is appreciated. I am still looking for a how-to thread on changing the LIM gaskets.

TIA

Allen


ETA:

I bled the system well after flushing it and have also replaced the thermostat.

you mean puddles over the lim bolts? not the heads...the lim bolts to the heads.

your car is eating coolant possibly.

Originally Posted by scottydoggs

you mean puddles over the lim bolts? not the heads...the lim bolts to the heads.

your car is eating coolant possibly.

I mean coolant is on the sides of the heads, like it is weeping down from somewhere higher like the intake manifold. I'm going to go take some pictures to post up to show everyone exactly where it is showing up at.

lim... lower intake manifold

LIM gaskets would not account for the oil loss.

It only has 111K but it's already a 12 year old car, probably with the inferior plastic LIM gaskets.

Make sure the Positive Crankcase Ventilation system is in working order.

^^^^^^^^^ yes what he said. just be sure to upgrade to metal lim gaskets

Originally Posted by FordMan77

Time to replace the LIM gaskets, valve cover gaskets, PCV, injector o-rings and coolant elbows. Betcha that will take care of all of it. Oh, and also check the oil pressure switch to see if it's leaking. That could account for your oil loss.

Thanks for the help. While I haven't looked underneath recently, I can't imagine the oil pressure switch could be leaking because there is no oil dripping from the engine, a clogged PCV is more in line with my signs and symptoms. I do occasionally have a rough idle and have noticed my fuel economy dropped from mid 20's to about 19-20. I'll try the above and get back to you all.

Ok, I wanted to update here.

I just replaced the following:
LIM Gaskets with the aluminum ones
Coolant elbow on the belt side, the one with even sized ends.
All the associated small gaskets, grommets.
valve cover gaskets and the grommets there as well.


To be honest the old LIM gaskets did not look too bad at all, they were the older plastic/nylon with rubber inserts but did not appear to be degraded or leaking anywhere. Since I had already made it that far I replaced them anyways. What definitely did need replacing though were the end gaskets between the valley and the LIM, I believe that is where my oil has been leaking from, but it is too soon to tell because the leak has been slow. I'll need a few weeks before I'll be able to tell if I'm still losing oil. The inside of the LIM was not too bad either, intake tracts are free from gunk (just carbon buildup). The plenum or upper intake manifold was not too bad inside either, just some varnish and gunk. The coolant that was in the LIM was clean and looked good. No globs or gunk in it.

Since last summer I have replaced:
Thermostat with 180 degree new gasket/seal
coolant, twice now since I drained out 2 gallons with the LIM gasket job.


All of this and I am still having overheating issues.

Recap of the symptoms
-ONLY overheats when sitting still WITH AC ON - with ac off I can idle at a standstill all day long in 110 degree heat without getting too hot.
-AC blows cold, even when the engine is getting too hot
-When driving at ~40mph or above with the ac on there is no problem
-AC compressor stays on constantly and does not cycle on and off, I thought it was supposed to cycle.
-I didn't mention this before, but last summer I blew an AC line, the one coming off the compressor and across the front of the motor. It was replaced by a mechanic and then proceeded to blow 2-3 more times. He fixed it under warranty each time and then finally switched to another brand, once he switched it it hasn't blown again

Diagnostics I have done:
-My cousin is a GM tech and suggested I make sure the AC isn't overcharged or under too high of a pressure after I told him about the AC line. I checked the pressure on the high side when the engine was about 220-230 coolant temp and it is 150-200 psi, which he said was normal.
-LIM gaskets and valley end pieces, associated gaskets, valvecover gaskets and grommets.
- Both fans are blowing (sucking actually) hard. blades are not broken and moving a lot of air
- no obvious obstructions or debris between the condenser and radiator
- Bled all the air, drove it, bled more air, drove it, got solid stream of coolant
- I don't believe the headgaskets are the culprit, but I haven't done a compression test. Engine runs well and does not hesitate, choke, stall, surge or anything that would suggest a loss of compression or a lot of coolant/oil in the cylinders.


That's all I can think of right now. I'm about at my wits end. I'm thinking maybe the waterpump is failing but I feel like that's not likely since it only overheats under the certain circumstance and feel like that would just be throwing money at random parts.

Any help is much appreciated.

I kinda thought LIM gaskets wasn't the problem but it's good that you changed them.
If there was a problem with LIM gaskets you would see some coolant in the oil.

The coolant loss could have been due to a combination of overheating, pushing coolant out the overflow, and leaking elbows.

For the oil loss: Have you changed the PCV?

From your original post: 220-240 degrees F is actually not that high. I think the fans kick on (without AC running) around 225 F.

From your last description, maybe the radiator's cooling efficiency has dropped. Are you sure you got all of the DEXCOOL out of the system?

It might be time for a new radiator.

Originally Posted by FordMan77

I'm leaning towards a coolant restriction somewhere then. Have you flushed the cooling system?

He has flushed and replaced DEXCOOL with the green stuff.

I don't know what he means when he says it's overheating only with the AC on. Is there steam coming from underneath the hood and gargling sounds? With a 195 Tstat the temperature can get up to 230 degrees before it changes direction and goes back down. I don't know what it should do with the 180 Tstat.

My car with a 190 Tstat and AC on the temperature never goes above 210 degrees but I have an over-sized radiator from ZZP. With the OEM radiator my temp would go up to 230 degrees before the temp would recover. It would go down to 210 and back up. This is why I went with the over-sized radiator. Best 200 bucks I ever spent.

Originally Posted by Rico

I kinda thought LIM gaskets wasn't the problem but it's good that you changed them.
If there was a problem with LIM gaskets you would see some coolant in the oil.

The coolant loss could have been due to a combination of overheating, pushing coolant out the overflow, and leaking elbows.

For the oil loss: Have you changed the PCV?

From your original post: 220-240 degrees F is actually not that high. I think the fans kick on (without AC running) around 225 F.

From your last description, maybe the radiator's cooling efficiency has dropped. Are you sure you got all of the DEXCOOL out of the system?

It might be time for a new radiator.

He has flushed and replaced DEXCOOL with the green stuff.

I don't know what he means when he says it's overheating only with the AC on. Is there steam coming from underneath the hood and gargling sounds? With a 195 Tstat the temperature can get up to 230 degrees before it changes direction and goes back down. I don't know what it should do with the 180 Tstat.

My car with a 190 Tstat and AC on the temperature never goes above 210 degrees but I have an over-sized radiator from ZZP. With the OEM radiator my temp would go up to 230 degrees before the temp would recover. It would go down to 210 and back up. This is why I went with the over-sized radiator. Best 200 bucks I ever spent.

Yes I did replace the PCV and the whole system there was pretty clean inside. I wiped out any residual gunk and put the new valve in.

I am quite sure, especially after tearing into the motor, that there is NO DEXCOOL left in there at all.

When I said it was overheating I mean just that. The temperature would continue to rise until I either shut the AC off, shut the car off, or the temperature warning light would come on and the car would kick the AC off itself. The times when I was not paying attention and let it get that far, the coolant is starting to boil over and you can hear boiling sounds through the firewall or maybe even from the heater core. When I said 220-240 I meant that was as far as I would let it go before I would turn off the AC. The times I was not paying attention, By the time I noticed it when it set the temp light and kicked off the AC compressor, the temp guage is on the edge of the red section. I take this to be ~250. When the ambient air was hot, it would take only about 5 minutes of sitting still, either in stop and go traffic or a drive through or sitting idle in a parking lot, before the car would get to 240 degrees plus and still be climbing.


However, I can finally say that I think I have found the root of this problem.

I really always felt like it was an airflow problem, due to the nature of the car being stopped when the problem was happening. I pulled the fans connectors off individually to make sure that both were working well and they are both working very well and moving a lot of air. So after talking to my cousin more, he felt it was either a waterpump (not likely he said) or something was blocking air movement between my condenser and radiator.

I have previously sprayed out my condenser and radiator by taking a high pressure washer and blowing it through the lower opening, but have just always done this for a few seconds when I'm washing the car. So to make sure there was not any mud or other gunk in between the two I took a garden hose and just ran it through the radiator and through the condenser. I ran the hose through both of them from the bottom, from the top through the little inlets to the side of the Pontiac emblem, and from the engine side. After a little while of running the water through I started to get some dark hair/fibers coming out in clumps, then more and more and more. After looking at them and with the smell of what was coming out I believe it was a mouse nest at some point in time.

So here is my theory,
Some time before I even had the car, the previous owner drove it home during the winter, left it parked outside, and some small critter
(a mouse I think) decided it was a nice warm place to make a nest between the radiator and condenser. I'm sure the creature found it not such a nice place the next time the car was started and abandoned it's house in short order, but the nest stayed nestled in between my heat exchangers. Who knows how many years it has been in there? It took me at least an hour of running water through to get everything out

So to sum up, if you are having overheating issues be sure to wash out (not flush but rinse through) your radiator and condenser. I feel kind of dumb for not doing this first because it seems so simple and like one of the first things I should have tried. But I'm going to swallow my pride and post it up here anyways so the next guy trying to figure it out doesn't overlook this step like I did at first. *Just because your fans are moving a lot of air does not mean there is not still and obstruction!!*

Thanks to everyone who helped in this thread, your help is much appreciated!

Interesting. I knew it had to be something with cooling efficiency.

Let us know about the oil loss; if the LIM gaskets helped. I'll bet the problem was the valves cover gaskets. Was the area around the top of the exhaust manifolds caked in black grease? These will leak very slowly over time and you likely won't see any oil on the ground.

At only 111K miles? I doubt it but it's easy enough to check.

Remove the UIM and inspect the part of the plastic manifold that the EGR stove pipe comes up through. Coolant runs right around there and the heat can cause a pin-hole or two. Coolant goes into the manifold and right out the exhaust.

Also inspect the o-rings right there that run up into the TB. These leak as well.

Mileage doesn't matter??