Diesel Fumes In Cabin Part 2

Hi,

If anyone can recall I was the one who started to get diesel fumes in the cabin with recirculate air on after driving through the cold-start cloud, driving along at a good clip and opening a window and if sitting idling. I traced it to a vent located in the rear left of the car obscured by the bumper (impossible to get at without removing the bumper). I took it to my dealer who ordered the part and I had it replaced this week. The mechanic believes that the defective vent wasn't even put on correctly and the fragile vent flaps were mangled as a result. So whenever exhaust fumes made their way up under the car in the vicinity of the vent fumes were getting in the car and actually pulled through the car as I was driving if I opened a window (ever with the window shut they would still slowly make their way in).

This week after the vent was replaced there is no problem whatsoever. I back through the cold start cloud, no smell ... driving along and open a window abit ... no smell. Just like when I bought her. Of course, depending on wind and the like you'll still get fumes in the car but not like when that vent was busted.

Check it out if you've started to have this problem on your 1999? - 2003?.

My postings:

"Diesel Smell in cabin normal?"
http://forums.tdiclub.com/cgi-bin/ultimatebb.cgi?ubb=get_topic&f=35&t=002947&p=#000009]http://forums.tdiclub.com/cgi-bin/ultimatebb.cgi?ubb=get_topic&f=35&t=002947&p=#000009

"Little Rubber Flap"
http://forums.tdiclub.com/cgi-bin/ultimatebb.cgi?ubb=get_topic&f=35&t=003027&p=#000002]http://forums.tdiclub.com/cgi-bin/ultimatebb.cgi?ubb=get_topic&f=35&t=003027&p=#000002

Cheers,

Mark./

[ November 23, 2002, 07:20: Message edited by: Kato ]

I love a happy ending .

Originally posted by Dana Bartholomew:
I love a happy ending

.

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<font size="2" face="Verdana, Helvetica, sans-serif">

I too believe I have a problem with this vent. I don't notice a diesel smell but then again I work around diesel machinery all day long so maybe I'm just used to it. My problem is when I drive on the highway with the recirc on, I get a cold draft from under the back seat. I assume its coming from the trunk and thus my belief that my vent is also broken or stuck.

I guess my only question is did the dealer have to remove the bumper to replace this flap and how much did it cost you? If it is too expensive, I will just leave the recirc. off for the winter so I dont freeze my toes

Originally posted by wingnut:
I guess my only question is did the dealer have to remove the bumper to replace this flap and how much did it cost you?

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<font size="2" face="Verdana, Helvetica, sans-serif">The bumper must be removed to access this vent adequately. It was covered under warranty so it cost me $0

Interesting thing this vent located behind the bumper. I've concluded that it is this vent that causes the following phenomenia to occur. Try it and see ... or maybe you have already noticed it! It has been confirmed by several other Jetta owners.

Initial conditions: Driving on the highway, all windows up, sunroof closed.

Test: Fully open the passanger rear window while maintaining highway speed.

Result: The driver will be greeted with severe pressure pulsations that seem to burst the ear drum.

I believe the cause of the pulsations is the repeated seating and unseating of this vent, but have been unable to confirm. I'd like to disable the vent one day and see if the pulsations go away.

Until then, whenever a rear passanger lowers a window, I'll just have to continue ensuring that a front window is opened also.

Diesel Fumes in Cabin Part 2: Fixed my problem!

Just wanted to let you know that your posting on replacing the rear vent on my Golf TDI 2001 fixed the fumes in the cabin problem. As it turned out, 1 of 3 of the little rubber flappers had disappeared all together. The Volkswagen dealer was as usual unhelpful and stumped, as was my other mechanic. Thanks again, I enjoy my car a lot more now!

The cost with my Mechanic for the work (in CAN $'s) was as follows:
Rear Vent Assembly parts: $60.49
Remove and Replace Bumper and Replace Rear Vent labour: $112.50

I assume this is present on both Jettas and Golfs??
I couldn't find it detailed in my Bentley. Just removing the rear bumper reveals it?


Dave

Vent/Diesel-Cabin Smell/Stumped

VWGOLFTDI said:

Just wanted to let you know that your posting on replacing the rear vent on my Golf TDI 2001 fixed the fumes in the cabin problem. As it turned out, 1 of 3 of the little rubber flappers had disappeared all together. The Volkswagen dealer was as usual unhelpful and stumped, as was my other mechanic. Thanks again, I enjoy my car a lot more now!
The cost with my Mechanic for the work (in CAN $'s) was as follows:
Rear Vent Assembly parts: $60.49
Remove and Replace Bumper and Replace Rear Vent labour: $112.50

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OK, I'm stumped. Having just come into possession of a 2005 Golf I've noted that a long highway drive will result in cabin/diesel smell syndrome. What exactly is the purpose of a vent situated on the back-end undercarriage of a vehicle. What's it venting and what actuates it? Seems like design logic would dictate you wouldn't stick a fresh air vent anywhere near an exhaust plume (but then again I can think of a lot of loading docks with fresh air intakes within ten feet. 'Guess architects thought occupants love diesel exhaust from delivery trucks). If the vent is covered with duct tape and plastic what happens? When push comes to shove I can get my fresh air cracking a window.

MM: you are refering to the 'coke-bottle' phenomenon. I've had this happen to me on many different cars. The more aerodynamic the car, the more pronounced the effect. It has nothing to do with the vent.

The flaps are supposed to close under negative pressure, like when the recirc is on. Also I'm guessing that at highway speeds there is relatively more negative pressure at this position on the rear of the car than inside the cabin so the flaps will open but no exhaust will come in. What happens over time is that the flaps warp and dont close, or break off.

Initial conditions: Driving on the highway, all windows up, sunroof closed.

Test: Fully open the passanger rear window while maintaining highway speed.

Result: The driver will be greeted with severe pressure pulsations that seem to burst the ear drum.

On my NB, if you open up the sunroof and have all the windows closed, you get the same ear burst pulsation. I never knew what it was, but simply learned to not open the sunroof all the way with the windows up, but just to the 90% open position.

Interesting phenonomen.....

I have a 98 NB...as a new owner I am not sure if i HAVE the same problem or not, but I do smell some diesel fumes...is there a cure for me?

mailman said:

Interesting thing this vent located behind the bumper. I've concluded that it is this vent that causes the following phenomenia to occur. Try it and see ... or maybe you have already noticed it! It has been confirmed by several other Jetta owners.

Initial conditions: Driving on the highway, all windows up, sunroof closed.

Test: Fully open the passanger rear window while maintaining highway speed.

Result: The driver will be greeted with severe pressure pulsations that seem to burst the ear drum.

I believe the cause of the pulsations is the repeated seating and unseating of this vent, but have been unable to confirm. I'd like to disable the vent one day and see if the pulsations go away.

Until then, whenever a rear passanger lowers a window, I'll just have to continue ensuring that a front window is opened also.

Click to expand...

I have this same pulsing issue with my Passat. It is almost like a sonic boom. I keep the rear window switches disabled because of this.

Rear Vents

Recently I have been getting exhaust fumes in the cabin. I came across this post which seems like it may be the cause of my problem. Does anyone know the actual part number or name of the rear vents, gaskets etc.? I would like to replace this myself as I don't have a high opinion of my local stealerships repairs. Also, is it fairly difficult to replace and do I have to do anything such as disabling the air bags etc before removing the rear bumper.

RT1 said:

OK, I'm stumped. Having just come into possession of a 2005 Golf I've noted that a long highway drive will result in cabin/diesel smell syndrome. What exactly is the purpose of a vent situated on the back-end undercarriage of a vehicle. What's it venting and what actuates it? Seems like design logic would dictate you wouldn't stick a fresh air vent anywhere near an exhaust plume (but then again I can think of a lot of loading docks with fresh air intakes within ten feet. 'Guess architects thought occupants love diesel exhaust from delivery trucks). If the vent is covered with duct tape and plastic what happens? When push comes to shove I can get my fresh air cracking a window.

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You CANNOT tape these over. Period. Your ventilation system will not work correctly and you will fog the interior. Don't believe me? Try it.

jasonTDI said:

You CANNOT tape these over. Period. Your ventilation system will not work correctly and you will fog the interior. Don't believe me? Try it.

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Ok then, we won't be doing that. Actually after three weeks of driving the problem seems to have self resolved... or I got used to the fumes. I'm thinking maybe the clean-up of the engine, to make pretty for re-sale, might have left enough residue in place that the highway driving had something to cook off. All seems well at this point.

Who said anything about taping over the vent?!

Does anyone have answers to My questions?

jasonTDI said:

You CANNOT tape these over. Period. Your ventilation system will not work correctly and you will fog the interior. Don't believe me? Try it.

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It seems I have missed some activity in this thread.

I was checking because the problem is back (diesel smoke in the cabin).
It seems that the flaps on the exhaust side are not closing fully.

My question is this - has anyone tried to block this vent without removing the bumper? I was thinking of using some of that spray foam insulation to plug it up.

My questions to Jason(or anyone else that cares):

1) I thought the purpose of these vents was to equalize the air pressure inside/outside the car. Wouldn't this still occur (maybe not as efficiently) with only one vent left intact? (the one on the passenger side)

2) Even if both vents were plugged wouldn't turning the recirculate cabin air off defog my windows?

Your ideas would be appreciated.

Kato

I don't know about you guys but I never get the air pressure problem with just by sunroof open on the highway.

I had this same problem. So I ordered the new relief vents and proceeded with the install. I found a faq on VW vortex for rear bumper removal. That was a mistake, was for the mk4 golf, the jetta is alot different. It said it was for the jetta as well:

http://forums.vwvortex.com/zerothread?id=1939276

So I threw faq that away, remove tail lights and bolts under neath, remove 3 bolts under bumper, 3 bolts in each wheel well. No bolts inside of trunk. The relief vents are on the far right behind the tire, far from the exhaust. The old ones seemed to be perfectly fine, they would easliy seal with gravity, I replaced them any ways. I am thinking the real problem I had was, the left tail light was not tight enough, the gasket was full of road dust, interior and exterior exposure. And this is right above the exhaust outlet. I dont think the beaners ever tightened it enough at the factroy?

The moral of our story is: when you open the window or sun roof (negative pressure in cabin) and smell fumes, try to tighten the tail lights a little before you replace the relief vents.

Now I can drive with the window open and no more fumes.

On my Golf I can see the vents without removing the bumper....

When I remove the 'upholstery like' layer on the left/exhaust side. I have full access to the vent. I siliconed this one and covered it in aluminum tape.

I can see the right side by removing the little section for changing rear lightbulbs......it is the only one equalizing cabin pressure but it seems to work well....

Fumed out in my Golf!

Kato said:

On my Golf I can see the vents without removing the bumper....
When I remove the 'upholstery like' layer on the left/exhaust side. I have full access to the vent. I siliconed this one and covered it in aluminum tape.
I can see the right side by removing the little section for changing rear lightbulbs......it is the only one equalizing cabin pressure but it seems to work well....

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A pic of this would be nice. I'm getting fumes if I crack a window or the sunroof.

No fumes through the vents or if I just open the sunroof in the vent position.

spoilsport said:

A pic of this would be nice. I'm getting fumes if I crack a window or the sunroof.

No fumes through the vents or if I just open the sunroof in the vent position.

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Most likely the vent on the exhaust side ....

I'll post pics later today of the vents.

Last year I also purchased a couple of exhaust tip extensions to route the exhaust out from underneath the car so the fumes don't 'pool' in the recesses of the vehicle...

Here are the pics:

These two are on the driver's side -shown without the moulding pulled off and then with it pulled off ... showing the sealing job I did on the vent.







This is the passenger side, untouched, and still functioning (the vent is in-line with the wires in the middle of the pic):




Here's the exhaust tips - they're not beautiful but they're almost two years strong and haven't rusted off yet...

Thanks!

Great pics. I appreciate you doing this!

spoilsport said:

Great pics. I appreciate you doing this!

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No worries ...