Exhaust fumes in cabin, holes behind rear seat

[59Canadian]

My wife has been pointing out for a while now that there is always a strong smell (to her) of exhaust fumes in the cabin of our car. I’ve been riding in and driving old cars since I was a kid so I don’t really notice it that much, but I feel I should try and get to the bottom of it.

My car has had the heating system removed so it’s definitely not anything to do with heat exchangers or anything like that. All of the holes under the rear seat appear to have been patched and sealed properly.

While checking around for the source of the fumes, I discovered 2 holes in the sheet metal on each side of the car, directly beside the rear seat back. They appear to be factory holes to allow access to something behind the metal, possibly the fasteners for the exterior trim piece. Could these holes be the source of the exhaust fumes being drawn back into the car? Are these holes supposed to be plugged and the PO didn’t bother replacing them after the car was painted?

I’ve attached some photos for reference.

Thank you.

[zerotofifty]

Assure the engine bay pillows are installed. These go in the pillar openings on either side of engine bay, these will keep fumes out and reduce noise. see link

https://www.thesamba.com/vw/forum/viewtopic.php?t=734234&highlight=pillows

in our old Bugs the pillows were made of upholstery scraps, later bugs used expanding foam the expanding foam however tended to trap moisture between it and the sheet steel, resulting in bad rusting. The cloth pillows can breathe, and thus will not trap water. many late Bug has this area, right behind the rear quarter window rust thru completely do to the expanding foam.

use of pillows can prevent the smells from getting from engine bay to the cabin

check that yours is present.
_________________
Sorry About That Chief.

Give Peace a Chance.

Words to live by.

[tasb]

There was someone selling reproduction pillows for the engine bay but I'm not finding them now. They were triangular shaped. Really any kind of fabric shoved in the cavity would work.
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1957 Kombi low mileage 36 hp governor equipped M 178 Slow Drag Winner 2014, 2015, 2018

1965 hardtop Deluxe Microbus owned since 1990 M 620 factory 12 v 1500cc

1961 (October)Single Cab- Road Trip Workhorse

Member# 2059

[runamoc]

put the tool box on the floor. Front end collision will turn it into blunt trauma to the back of your wife's head.

As for your concerns over the holes, maybe fill the holes with expanding foam from a can.
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Daily driver: '69 Baja owned 45 yrs - Plan B: '72 Ghia
Yard Art: 2 Sandrails
Outback: '69 Ghia - '68,'69,'70,'72 Beetle - '84 Scirocco, GTI - Pair of '02 Golfs- '80 Rabbit Diesel
VW Wiring = It's just wires

[OldSchoolVW's]

[zerotofifty]

[scrivyscriv]

I like to share 3M's tech youtube any time these kind of topics come up!


Here's one with an overview on their foams:

Link


And this one is about installing it:

Link


Foams and adhesives are a SCIENCE. They are engineered for specific areas, with specific goals. The automotive collision industry has volumes of great information people like us can use to make good choices using products that weren't even on the radar 50, 60 years ago!
_________________
Robert in Memphis
Dünkelgrügen 1967 Java Green bug thread
Engine rebuild thread
If you're ever in the Memphis area, you are welcome to stop by for advice and help.

[zerotofifty]

[scrivyscriv]

I thought about that. But it seems like the late model foam problem stems from the crescent vents. I know I’ve pulled foam out of my C pillars in my ‘67 bug and I don’t have any of the death foam rot associated with late models.. notice all the topics you linked to are exclusively late model.

I’m betting it’s a combination of wind-driven moisture intrusion from the crescent vents, and an absorbent foam behind them. I’ve been looking into the 3M foam for a while now and I think I may give it a go.
_________________
Robert in Memphis
Dünkelgrügen 1967 Java Green bug thread
Engine rebuild thread
If you're ever in the Memphis area, you are welcome to stop by for advice and help.

[zerotofifty]

Water may enter via the window seals leaking as there is a pathway in the window channel. Water may wick in via the fender bolts. water may wick in at roof seam.
Water may enter from washing engjne bay. in cold humid conditions, condensation can also wet the foam by water dripping down the C channel from roof arch.

Note in the photo the drain holes in window seal channel, and caulking cracks at roof seam, two possible pathways for water to enter the death foam zone.

I highly advise against the use of the foam.
_________________
Sorry About That Chief.

Give Peace a Chance.

Words to live by.

[scrivyscriv]

Please let me preface with this: I don’t mean to be contentious.
Unfortunately advanced topics like body foams and adhesives tend to be quite polarizing, and it’s not just on VW forums. Without an engineered design to follow - because modern NVH and structural foams weren’t in the industry when our cars were being produced - everyone is just speculating on what is or isn’t a good idea.
Adhesives and seam sealers have a better defined role but you see topics all the time with guys completely misusing, say, 3M 08116 panel adhesive, explaining their rationale in a way that shows they have no idea what the OEM repair industry actually says you can and can’t do with it.

I admit foams are a big unknown for most of us, and we’ve all pretty much just seen the late model death foam as a reference for what poorly engineered foam practice can do. But surely it’s not as easy as “foam bad, pillows good.”

I really do believe the evidence shows “death foam” being directly caused by the added crescent vents. C-pillar foam isn’t exclusive to late models, but the corrosion perforation in that area is.
Here’s a topic of relevance
https://www.thesamba.com/vw/forum/viewtopic.php?t=706621&highlight=death+foam
_________________
Robert in Memphis
Dünkelgrügen 1967 Java Green bug thread
Engine rebuild thread
If you're ever in the Memphis area, you are welcome to stop by for advice and help.

[runamoc]

[zerotofifty]

[zerotofifty]