Warren928

Anyone else have this problem?
Some rennlisters have said that you can get hot air coming through the shifter if your motor mounts are bad, but this is not the problem I am having.

The car has never seen a winter, no rusty exhaust , had my mechanic check out the exhaust, tighten clamps and seal it, but exhaust smell still coming in via the vents when I turn the fan on ONLY.

Any help would be appreciated

Mark

If your exhaust is good and has no leaks - are you sure it's exhaust smell??? No way for it to get in there! Did he check the ex. manifold? Any cracks or bad exhaust manifold gaskets? (you'd HEAR that!!)
Check to see if you have any fluid leaks that may be getting on something hot and then the odor is 'wafting' up and being sucked in thru the cowl and then thru the fan. The rear cam plate cover gaskets are known to leak - which will drip oil right on the exhaust. THey are a PAININTHEASS to replace...but that would be my best guess.

Does this happen only at certain speeds...or over all, including sitting @ idle?

Mongo

Thanks thats what I need to hear for my project this weekend

Warren928

Mark,

More characteristics:
1)Its not a burning oil smell.
2) I don't hear any clapping noises or loud exhaust coming from the exhaust or manifold which usually indicates a leak.
3) I smell it generally if I am between a dead stop and 5 mph. After that, its gone.

A smaller pipe connected to the system could possibly be the culprit...?
Anyone ever find on their shark:
1) A bad EGR hose or PVC valve hose or pipe that could be pumping out stinky air and into the heating system? That might not make alot of noise
2) Could the air pump not be working and I am getting exhuast backfeeding through it or from a cracked air pump to cat pipe?

Not sure where all these lines run, but I have another clue. There was a mild exhaust made residue stain on the organ pipes and hood insulating cover about 4-7" from the front of the organ pipes.

Any ideas what could cause both the smell and an exhaust residue in that area?

Bill51sdr

Do you still have the light blue rubber caps on the CO tubes in the engine bay, next to the airbox (if yours still exist...)? If not, this may be your problem.

Garth S

The 'sniffer' tubes Bill mentiones above ( w. the blue caps) can fail at the exhaust manifolds.

Warren928

Bill and Garth,

The light blue caps that are found in the engine bay, next to the airbox-- What is their purpose for having a cap there?

Do the sniffer tubes connect the carbon monoxide sensors to the Exhaust manifolds? I am wondering if I would be able to see them more clearly If I was under the car. If those are bad, how much work and cost in parts am I looking at?

Normy

If you have exhaust smell coming into the HVAC system, then it most likely is entering from the blower fan, which is located on the passenger side of the car in the cowl area [that is, next to the windshield wiper mechanism].

What sort of exhaust leak would allow exhaust into this area? Possibly the sniffer tube, but also a leaky manifold.

This might be a dumb question, but do you smell this smell when you have the sunroof only open? The sunroof can create a negative pressure area inside the car and draw heat/odors into the cabin from around the shifter boot. Does the exhaust smell like its been through the catalytic converter?

Leaks like this can be tough to localize. My Aerostar minivan has a small exhaust leak that causes no problems but gives it a distinct exhaust sound. I can't find it and neither could an exhaust shop.

N!

AO

Garth S

The cap is removed for access by an exhaust gas meter ( CO, etc.): The tubes enter the exhaust manifolds either side - and as you guessed, can be seen from underneath. It may be worth a look to confirm that they are attached and free of cracks, pinholes, ...
If I ever had to repair one, I'd screw in a metric thread pipe plug .... ~$1

Warren928

Normy,
I would say the problem does not get worse with the sunroof open. Does this car have an EGR valve and pipe running to the intake manifold? If yes, where is it located and what does it look like if it has gone bad or leaking?

The exhaust manifold sounds quiet, so I am assuming no leaks, plus the gaskets were all changed 30k miles ago.

The sniffer tube sounds like a very good lead and I am going to check that out this week.

Garth,
Sounds like an easy fix for the blue caps. It also appears to be a relatively common problem that the caps get broken or are missing.

Big Dave

Yep, BOTH of mine were bad. One was completely broken off, and the other had a hole in it that looked like someone intentionally opened the tube up like a sardine can.

Both tubes are now gone, and the the ports in the exhaust manifolds are plugged.


P.S. The hollow bolts that plug into the manifolds can be hard to access, and the narrow sniffer pipes connected to them are very likely brittle due to rust.

Bill51sdr

Those caps are there to help prevent the same problem you are having. If they aren't there, you are getting raw exhaust in the engine compartment inches from the firewall and blower fan.

Livio928

Anybody have a photo of how the sniffer tube serpentines up the firewall? My tube has numerous bends in it that I cant figure out how to lay it out. I only have one tube. Should there be two or is it that it can be on either side of the engine bay?

17prospective buyer

Livio mine had one for each bank. It's been a while since i removed all that, but i remember the passenger side tube was clamped to the air pump recirculation/bypass valve components. Can't remember where the driver side fastened to.