Exhaust smell in cabin

[chewiebarker]

This is a somewhat broad question, but I searched prior posts and I really don't know where to begin to fix this.

My kids keep complaining, and I agree with them, that the cabin stinks of exhaust fumes (and gas fumes to some extent) when we drive in my 1971 K20 Suburban. I suppose there are lots of possible causes but here are the things I wonder about perhaps being the cause.
1. The seals on the doors are all screwed up, or missing
2. The PO vented the exhaust out the side of the vehicle in front of the rear wheels. The exhaust runs straight from the headers into cherry bombs (brand unknown) and out. No muffler of any type.
3. Old cars just stink.

I am less suspicious about the location of the pipes because I have seen other people exhaust their cars at that location without complaint of fumes and I assume that while moving the exhaust would trail behind regardless. It doesn't seem to matter if the car is actually moving or parked. No matter how fast I drive, it still stinks. Is it typical and to be expected that these old trucks are just going to stink? I don't know where to start to try and remedy this (other than take it to a shop...$$)

Any advice would be appreciated!

[pwdcougar]

No leaks at all Chewie? I'd suspect that it is the exhaust tips exiting from the side. Where did the stock exhaust exit? The rear or behind the rear wheel?


Paul

[rocknss]

Did you check for leaks in the exhaust? I had the same problem and l found a leak in the exhaust manifold.

Also my exhaust exits in front of the rear wheels.

[vectorit]

The only time I smell fuel while driving my burb, is when I have topped off the tank and take a hard right turn. Since the fuel will slosh up the fill tube, and some can get past the cap and dribble down the side of the truck.

I would check your fuel line from the tank to the engine, and make sure you don't have rubber hose that has perished so much that it weeps fuel. There is rubber hose at the tank, and of course at the fuel pump from the frame line.

Your YOM truck would have a fuel tank charcoal can to direct tank vapors into, and a lot of time that canister has been removed and the vent line is tucked somewhere around the passenger inner fender.

Headers are notorious for leaking... Have you tried running the truck at idle at night, and then search around with a bright flash light to see if you can see exhaust from the heads or collectors?

Is your PCV working properly? If not, then it could be filling up your engine compartment with crank case vapor which smells like exhaust in bad situations. Are you running an open air cleaner? If so, the PCV fumes could be escaping from the filer element.

How is the body when it comes to rot? If there are rust holes in the rocker areas around the exhaust tips, then fumes could come in through the rust holes.

How is the floor in the rear? Over the years, lots of holes end up being drilled into it. The seat belt holes are big holes, and there are up to 8 of them drilled into the wood for seat mounts.

The spare tire tub has a drain hole in it, and I have always kept it plugged with a cap plug.

For years my burb ran with headers, and exhaust exiting before the rear tires. Never had a problem with the cabin filling with fumes from exhaust.

[Manatee Poacher]

Check for exhaust leaks at the manifold as stated above. I had the same problem.

On mine I also was missing the grommets in the firewall, and had a cracked transfer case boot.

Those 3 things solved it for me.

[PowerdbyChevy79]

first place i would look is the firewall.. over the years the grommets can and will start to break dow..if you got any kind of exhaust leak at the manifolds it will suck into the compartment... also having the exhaust at the side instead of the rear is probably an issue too...but hit up the firewall first.. my .02

[LockDoc]

-
If it is an automatic be sure and check the clutch delete plug to make sure it hasn't fallen out. If it's a stick check the clutch rod seal.

It could be sucking fumes in around the rear doors/hatch if the rubber seal is bad....

Just some more ideas.

LockDoc

[chewiebarker]

Thanks everyone. Looks like I have a good deal of work to do.

The charcoal can is definitely missing - I already bought one from a board member to replace it, just haven't installed it yet. Rear hatch and other doors are missing seals, so I will have to remedy that. Also, I have never checked to see if the exhaust manifold/headers might have a leak. That will be one of the first things I check. There are also plenty of holes in the rear bed. I really just didn't know where to begin, so thanks all for your suggestions!

[AzDon]

I have the same problem with my 68 suburban, and my exhaust exits straight out back past the rear bumper..... I have completely sealed up the firewall, put bolts in all the unused holes in the floor, and completely sealed the entire floor with white elastomeric, which sealed gaps that leaked when the truck was new..... I have also installed additional weatherstripping around the rear hatch and gate. What I have not done is re-do the seals around the taillights and side marker lights.... I also DO have an open element aircleaner.... The fumes on mine are definitely exhaust and not raw fuel.... I notice it mostly when running with the windows up.....
What I'm thinking is that we've simply forgotten what riding in a car was like before fuel injection! We've gotten used to breathing air without hydrocarbons and now we notice how much raw gas and exhaust stinks and how it makes us kind of sickish..... Back in the day, I remember "car sickness" was pretty common and probably was mild co poisoning.... I can't remember when I last heard of a case of car sickness..... I want to put the exhaust out the side ahead of the rear wheels to simplify the under-car layout, but have worried about making the problem worse. The factory exhaust dumps on most wagons are out the side pretty close to the rear, presumably to keep the exhaust out of the turbulence behind the car.... I dont know the answer, but will be watching this thread!

[72MARIO]

The exhaust on our butbn exits behind the rear wheels on a angle out. Never had a issue with exhaust coming inside. I don't believe exiting the pipes under the rear bumper is a good choice or before the rear wheels. There must be some reason as to why the factory chose behind the wheel