White Smoke from Exhaust (what could this be?)

pagluy

pagluy

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I was sitting at a light the other day with the windows down and suddenly noticed my car was getting smokey inside. It was spitting out of my exhaust. A white smoke with an odd smell. It was sort of a "sweet" smell, though I can't really describe it.

What could this be??
 
I am going to guess antifreeze. Has your car been overheating lately? I've seen this happen in the past with blown head gaskets (due to overheating).
 
jjcool00 said:
I am going to guess antifreeze. Has your car been overheating lately? I've seen this happen in the past with blown head gaskets (due to overheating).
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I bet you haven't seen this (headgasket failure) on the 3.9 V8. Of course, it's not impossible.
 
Are you sure it was coming out of the pipes? I've had a plastic bag to blow up under there before and get stuck on an exhaust part. It made a lot of smoke and smell as it melted.

Do you use full synthetic oil? That doesn't always burn blue.
 
joegr said:
I bet you haven't seen this (headgasket failure) on the 3.9 V8. Of course, it's not impossible.
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No sir, I have not! Last few times I've seen it happen were on a Bonneville, a Town Car, and a Caddy.
 
Car has never overheated in the 4+ years I've owned it.

I always use Motorcraft/get oil changes at the dealer. I am positive it was coming out of the rear (I pulled over and looked). I've had a few times in the past year where I started it up and some not-condensation white smoke would billow out for 15-20 seconds and then go away. This was the first time it did it after I'd been driving it a while, and with so much smoke. Haven't been able to get it to smoke yet since though (this happened yesterday evening).
 
pagluy said:
Are you saying I've got a bad head gasket?
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I believe he was saying that the chances it is your head gasket are extremely minimal. Now that you said your car has never overheated I would put it the chances of it being your head gasket at next to near zero.

Have you recently added anything to the fuel? Additive? Maybe you got some gas that had a lot of water in it, filling up 91+?
 
If you havent replaced cooling parts in 4+ years I'm guessing its time. My bet is hairline crack somewhere causing a leak not big enough to overheat the car...yet. Only white smoke i've ever seen from the LS has been coolant/cooling system related and condensation in the exhaust pipes during cold weather.
 
just finished replacing the upper intake (plastic) on Michaels grandmothers buick 3.8 . the egr had eaten all most completely thru the coolant passages and allowed coolant to drain into the cylinders. after seeing that coolant on the valves pulled the plugs and drained the coolant from the cylinders. changed the oil which was contaminated and the filter. started it up and had to open both doors to the garage as it filled up with smoke. good engineering GM save a little weight but blow the engine. we where lucky that it doesn't miss or knock holds good oil pressure. time will tell. hope you have good luck and don't lose your motor. check your oil level to see if it is getting antifreeze in it. JD
 
pagluy said:
I was sitting at a light the other day with the windows down and suddenly noticed my car was getting smokey inside. It was spitting out of my exhaust. A white smoke with an odd smell. It was sort of a "sweet" smell, though I can't really describe it.

What could this be??
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Was this light at an incline?
 
I'm agreeing with Mlara. I recently had the t-stat housing take a crap and it was spitting coolant all over the engine/exhaust. As I drove, I looked behind me and noticed tons of white smoke which I thought was coming out of the exhaust, but was just running under the car along the exhaust and exiting.
 
I will take a good look inside the engine bay & underneath and see if I can spot anything like that! Thanks!
 
I recommend checking the function of the crankcase ventilation system and the PCV valve. Make sure there is no sludge build-up and the PCV is working properly.
 
LSV8FAN said:
I recommend checking the function of the crankcase ventilation system and the PCV valve. ....
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That would be a pretty good trick for him. The 3.9 V8 doesn't have a PVC valve.
 
I'm guessing the t-stat housing, the 'tree' plastic piece by it, or the line that runs over the engine near the back. All 3 caused the sweet smell in my LS once it warmed up
 
LSV8FAN said:
I recommend checking the function of the crankcase ventilation system and the PCV valve. Make sure there is no sludge build-up and the PCV is working properly.
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joegr said:
That would be a pretty good trick for him. The 3.9 V8 doesn't have a PVC valve.
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Huh ?

Positive crankcase ventilation (PCV)

no valve !!!
 
BigRigLS said:
Huh ?

Positive crankcase ventilation (PCV)

no valve !!!
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Wow, I misspelled PCV. That should have been hard to do...

Yes, the V8 has a PCV system, but no PCV valve. My possibly flawed understanding is that the PCV valve (when present) is there to prevent backfires (combustion in the intake) from igniting fumes in the crankcase. Apparently, the design of the 3.9 somehow (baffles maybe?) guarantees this without needing a valve.
 
blow by back into the intake mixture ... kinda odd, what does it do with it then.
 
I'm sorry, I'm leaving out words cuz I'm eating BBQ patato chips right now.

how and where do the gasses go, not like it has no gasses, right ?


I learned long time ago it had a valve-less PCV system, just never looked into how it's supposed to work.
 
Well, at the basic level...

There is a fresh air inlet to the crankcase that is after the air filter and the MAF, but before the throttle.
There is also a suction line from the intake manifold somewhere after the throttle that runs to the crankcase (usually on the other side).
Air travels through the crankcase and picks up the blowby gasses. They are sucked into the intake and from there into the cylinders where they get another chance at being combusted and sent out the exhaust.

As for how it manages to not need the one-way check valve, I haven't seen any real explanation of that.
 
There has to be a sort of restrictor orifice somewhere.
 
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