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TOPIC: White smoke from driver's side vent.

White smoke from driver's side vent. 07 Aug 2012 09:40 #9999


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Hi

While driving my 1988 928 S4 this weekend I noticed white smoke (a burning smell) emanating from the driver’s side door vents. I noticed it while stopped at a stop light. When I drove off, the smoke was gone and did not re-appear. The smoke amount was minor but it’s kinda scary..thinking your car is about to burst in flames. My questions are:

1) has this happened to anyone else before?
2) will this result in a hefty repair bill or is it a simple fix?


Thanks in advance

RJ
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White smoke from driver's side vent. 07 Aug 2012 09:48 #10000


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Did it smell electrical or like plastic burning?

If your window motor somehow got stuck "on" then perhaps that could be it, or if a pair of wires met (positive and negative) then perhaps a wire could melt.

Anything can be expensive, it depends on who does it, how they fix it and most importantly what you consider expensive :)
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White smoke from driver's side vent. 07 Aug 2012 10:40 #10001


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Hi Stan,

it had a burning paper type odor.

I found this explanation while doing an internet search for this issue.

"I have the EXACT same problem. The smoke (in my case at least) is cause by the oil breather tube leaking. It leaks a little oil on to the top of the engine which is hot, and it burns off. Under driving conditions, there is too much air flow to allow the smoke to drift up towards the vents. However, when you come to a stop, it will be able to flow on up in to the passenger compartment. Check the tube and its clamps (all located at the back of the intake manifold, underneeth it. "

My question is where is this breather tube located..is it easily accessible? I'm thinking oil leaking on a hot engine is not a good thing. :(
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White smoke from driver's side vent. 07 Aug 2012 12:46 #10006


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RGJ;10303 wrote:
Hi Stan,
it had a burning paper type odor.(

Sorry, I am confused, I read your post as that it was coming from the door on the driver side. I think you need to open the hood to find out whether the issue is there or in the door. Only after you determine that should you be considering how difficult it is to remove parts.
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White smoke from driver's side vent. 07 Aug 2012 13:17 #10007


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If you had oil dripping on to anything hot, it would not smoke in to your HVAC system. Take off your door panel and work you way to the front until you find out what was burning.
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White smoke from driver's side vent. 07 Aug 2012 13:17 #10008


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Hi Stan,

your initial assessment was correct. The smoke was coming from the driver's side door vents.

I thought maybe there was some linkage where if there was smoke under the hood it would be getting into the vents somehow.

I did open the hood and my novice eyes did not notice anything unusual...btw I just got the car saftied on Aug 3rd.

I'll drive it again to see if the problem presents itself again.
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White smoke from driver's side vent. 07 Aug 2012 17:32 #10012


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I definitely had smoke coming through my HVAC system when coming to stop. After the car sat for a few days, enough oil would drip onto the exhaust manifold and during the first few miles the smell was drawn into the cabin during each stop through the fresh air intake. After a few miles the oil burned off and the smell went away.

There wasn't enough oil leaking to even reach the garage floor and finding the leak took some detective work...luckily it wasn't the cam tower seals as I originally thought. Cam seals were perfect too. It was the large donut type O-rings and small bushing seal behind each cam assembly.

Very cheap and very simple to replace on the 16V motor.
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White smoke from driver's side vent. 07 Aug 2012 17:46 #10013


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^^^^^^
Regardless it wouldn't smell like PAPER burning... Oil, paper and plastic (from wires) all have VERY different odors! Not sure WHAT we have in the car that might actually smell like paper burning though!
James
78 Silver / Black-white #295
84 Ruby Red / Black AO84
88 Dark Blue / Linen-Black
92 Polar Silver / Dark Blue 92EURO
93 Arrow Blue / Black
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White smoke from driver's side vent. 16 Aug 2012 08:30 #10199


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If you are getting oil smoke/odor into the HVAC system, check the hood seal at the rear of the engine compartment. There should be a rubber seal clipped to the top of the firewall at the back, holding down the (fragile) black plastic cover at the base of the windshield.

Another possibility for burning odors from the HVAC...
If you get a leaf into the HVAC inlet (base of the windshield, passenger side, under the black cover), it will often get onto the resistor pack located in the HVAC plenum. This resistor pack enables the varying fan speeds, and has several large nichrome wire resistors that get very hot when the fan is on low speeds. The burning leaf will cause smoke and odor, but will burn away quickly, and virtually never causes any problems.
Wally Plumley
928 Specialists
www.928gt.com
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White smoke from driver's side vent. 17 Aug 2012 03:31 #10230


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just a thought.
You have the stereo cross-over in the door, maybe you have something going wrong in there and you may want to pull the panel unless you are sure it is from the vent.

also if the tube under the dash is disconnected you may have something going wrong under there. You need to trace it backwards.
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