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Heavy white smoke from exhaust, Need advice

H

hewta

New member
Hi all,

I bought a 99 GTP a few weeks ago and have been loving it, Until Yesterday when I noticed a very heavy white smoke from the exhaust. Temp got up to 210* at idle, But cooled off after i started driving again and revving the enigne up to around 3k produced a heavy white cloud that you could not see through. Strange part is smoke does NOT smell like coolant or oil, but I am losing a good amount of both. I think the oil is being lost via a leaky valve cover gasket. Smoke was very white, no bluish color at all, and there are no puddles under the car making me think im burning it.

I've spent all day researching and browsing the forums, and found so much conflicting information I had to make a thead. My best (uneducated) guess is headgasket or LIM gasket.

My notes:

No oil in coolant or coolant in oil
No air bubbles surface with rad cap removed, but level does dip maybe an 1/8th in when revving, and raises again as rpm's drop.
temp stays consistent and cool while moving, and spikes a bit at idle.
No loss of power or fuel economy
Putting a piece of paper up to the exhaust makes droplets on the paper in 30 sec

It doesnt pour smoke contantly. Sometimes ill rev it and see no smoke at all, but after letting it idle for 30 sec or more i get heavy smoke on the next rev and a steady "puff puff" from the exhaust at idle.

from what I gathered, the LIM gaskets are poorly designed and notorious on these engines. They have coolant and oil passages, both prone to leaking. Can coolant enter the combustion chamber by a failing LIM gasket? I'm guessing it gets into the head and eventually makes its way into the chamber?

Going to do a compression test right now will post results. I've already ordered a leak down tester,but it won't be here for a few days.

Desperate for any suggestions/ideas. Sorry for my lack of knowlege, very new to these engine.

Thanks in advance.
 
Last edited:


It's very likely to be the intake gaskets or bad upper intake manifold. They can cause coolant to just be burned, and still have none show up in the oil.
 
02NavyBlue said:
It's very likely to be the intake gaskets or bad upper intake manifold. They can cause coolant to just be burned, and still have none show up in the oil.
Click to expand...

Very nice to hear. My compression gauge wouldnt thread into my plug holes so I won't know compression until I can buy a new gauge tomorrow.
 
If your engine runs fine you probably won't find any bad compression readings. As far as I know, when coolant if just burned and not in the oil, the EGR tube in the upper intake manifold is usually the issue. It heats up enough to deform the plastic and cause a leak. Dorman's new manifold comes with a metal sleeve to prevent that from re-occurring.
 
forgot to add my EGR is deleted. From what i saw it looks like the smaller square passages were failing in most cases. Are these coolant passages?
 
These?
DSCF5914.jpg
 


02NavyBlue said:
bad upper intake manifold.
Click to expand...
How does a supercharger aka metal UIM have a typical NA motor plastic manifold failure?

02NavyBlue said:
the EGR tube in the upper intake manifold is usually the issue. It heats up enough to deform the plastic and cause a leak. Dorman's new manifold comes with a metal sleeve to prevent that from re-occurring.
Click to expand...
The EGR tube is never the issue for a UIM failure, the UIM is. But again, doesn't apply because we are talking about a supercharged motor.

dbextreme said:
And while you are there... do this!!

http://www.grandprixforums.net/how-mod-lim-46931.html
Click to expand...
Not going to argue about modding a lim, however it's likely unnecessary since he's charged.

I've seen a few things leak coolant into the intake on a SC motor.
1. TB spacer: the fix, throw the spacer away and get a new gasket.
2. Coolant o-rings at the LIM to SC gasket. Not common, but it can happen. Do LIM and plenum gaskets, clean the tb, you'll be all set for years.
3. TB gasket leak: it's paper, it can leak. Swap it out.
 
BillBoost37 said:
How does a supercharger aka metal UIM have a typical NA motor plastic manifold failure?
Click to expand...

I was being vague about a diagnosis, I try to do that if people searching for a similar problem want answers. Usually I put in parenthesis "doesn't apply to you" but I forgot.

BillBoost37 said:
The EGR tube is never the issue for a UIM failure, the UIM is. But again, doesn't apply because we are talking about a supercharged motor.
Click to expand...
That was bad wording on my part, I know how it goes.

Thanks for clearing it up Bill.
 


BillBoost37 said:
How does a supercharger aka metal UIM have a typical NA motor plastic manifold failure?


The EGR tube is never the issue for a UIM failure, the UIM is. But again, doesn't apply because we are talking about a supercharged motor.


Not going to argue about modding a lim, however it's likely unnecessary since he's charged.

I've seen a few things leak coolant into the intake on a SC motor.
1. TB spacer: the fix, throw the spacer away and get a new gasket.
2. Coolant o-rings at the LIM to SC gasket. Not common, but it can happen. Do LIM and plenum gaskets, clean the tb, you'll be all set for years.
3. TB gasket leak: it's paper, it can leak. Swap it out.
Click to expand...

Good stuff, thanks guys. Compression checked out at around 140psi on all 6 cyl. I would do a leak down test but from what I gathered headgasket failures are very rare on these engines and probably isn't worth the time. Planning to do all the above gaskets. Couldn't find the "coolant orings" though. Anyone have a part # possibly?

Someone on the MNCLUBGP forums said stay away from the felpro kit (FEL-PRO Part # MS98014T) as they are prone to failure, but felpro has always been great to me. Any other brand recommended or just get oem?

The previous owner had LS6 valve springs on these heads, and removed and sold them during demodding around 5 years ago. Wouldn't the heads have to be removed to take the springs off? Suppose the LIM gaskets could fail in 5 years, but curious if the headgaskets were done then too.
 
hewta said:
The previous owner had LS6 valve springs on these heads, and removed and sold them during demodding around 5 years ago. Wouldn't the heads have to be removed to take the springs off? Suppose the LIM gaskets could fail in 5 years, but curious if the headgaskets were done then too.
Click to expand...
Heads dont need to come off to change the springs. As long as you get aluminum intake gaskets instead of plastic ones you should be fine on that.
 
I'm really having trouble diagnosing what its burning. Its a thick white smoke but doesnt smell like coolant or oil. Is there anything else that can get into the heads or combustion chambers. I think i read somewhere its possible to get trans fluid or PS fluid burning somehow. I've smelled alot of burning coolant on previous cars, and this just doesnt smell like it, although all those times it wasnt mixed with exhaust.

Some small droplets form in the exhaust tips when it idles for awhile, but to the best of my knowledge thats normal. Im losing a fair amount of oil AND coolant. The coolant needs filling every 5 days or so and the oil needs a quart and a half every 1000 miles. I know some oil is leaking onto my rear exhaust manifold because i see it burning sometimes, and im sure im burning some at 170k, but hopefully not THAT much.

Is there any definitive test I can do to be absolutely sure its burning coolant? Just does not smell like coolant or oil to me at all, very frustrating. My gut just tells me its not coolant, but again im no expert. Any input?

Theres no oil in coolant or visa versa so the leak would be strictly between the coolant passage and the combustion chamber. I crank the engine and no bubbles or air surface through the radiator cap. To me that kinda says headgaskets are fine. at 140 psi SOME air would at least get into the cooling system imo.

Sorry for being a noob and bombarding with questions, Just want to figure this out for sure before i decide if I just need gaskets, or if im in for a full rebuild or swap.
 
White=water/coolant. Blue=oil. Black=unburnt fuel. If you're loosing both, it doesn't eliminate them. And it doesn't have to smell like coolant to be coolant when coming from the exhaust.
 
Re: Heavy white smoke from exhaust, UPDATE with video

Heres a video

View My Video

Think its getting worse. It will only smoke heavily like that if its idling for a few minutes and I rev it up. If I were to rev it again in that video there would be little or no smoke. Like it pools up at idle maybe and higher rpm's burn it.

I'm sure theres some oil in there too but still think a majority of the smoke is from coolant. Has a bluish hue to it like oil but im still losing a ton of coolant. As for oil, what are common leak points on these engines? Was thinking either bad valve stem seals, possibly head gasket or of course shot rings.

Either way looks like im in for some fun. Any input?
 


Could be LIM, I remember mine looked REALLY bad at only like 80k miles. Also it could be TB gasket, mine failed going down the highway and dumped enough coolant down my intake to stall when I was cruising at 70mph, I got very lucky it didn't hydrolock or cause any damage.
 
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