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Exhaust fumes in car

I

Incept

New member
Hi, I'm hoping someone has experienced this issue, as my repairer is baffled! What I originally thought was a fuel smell entering the car, seems to be something stranger and more difficult to fix. After the car has warmed up, there is a low level but clearly perceptible smell of exhaust fumes in the car: but only when the heater's on. If the temperature control is turned to cold (blue mark) the smell goes almost instantaneously. Turn up the heating again and back it comes. In addition, form time to time the smell can be very strong with a more intense "˜fuel' component. This is my first 993 and I guess they might all do this! As far as I know, the two systems are distinct, so how can the exhaust be leaking into the heating system? Can anyone help before I have to dig out my dad's old gas mask! Cheers,
Chris
 
I'm not an expert and not had this problem on my 993, but it sounds as if your heat exchangers are leaking. This is a known problem on earlier 911's but not to my knowledge on the 993.

You need to sort this as fumes leaking in via the heating system can be dangerous on a longer run.

We don't want to hear you have been poisioned !!

Get your repairer to check the heat exchangers carefully and if he draws a blank take it to a specialist.

Regards

John
 
The 993 (like all air-cooled 911's) draws its heated air from around the engine. Fresh, cold air is drawn from the front of the car on the trailing edge of the bonnet which is mixed with the hot air as required. Any oil leaks etc which drip onto parts of the engine or crucially the heat exchangers will create oily smoke which will be sucked into the hot air intake and into the cabin. Lot's of 911's have a, how best to describe it, a newly painted radiator smell. It's to do with the olde worlde method of heating the air.

However an oily smell could be a leak onto the exchangers. Also the system has ducts under the car, ensure the rubber pipes to these are sound.

GR
 
Hi,

Thanks both of you.

Part of my problem is I've not owned a 911 before and what I'm smelling might be normal: just painted radiator? However, the smell seems more of an exhaust smell and it does go away if you turn the heating off.

It doesn't smell like burnt oil though.

I'll certainly get it checked out again by the repairer who is a 911 specialist.

Cheers,

Chris
 
There are some flexible rubber pipes that connect the exchangers to the metal ducts,some of these have to be removed on servicing/oil change.They could have crackes/split or been left off...worth a check around in them areas.
Also when I removed the rear seat backs and seat belt points (when fitting a roll cage) we had excactly the same problem from the bolt holes in that area?????
Check all the bolts are in.
 
Hi and thanks for the suggestions.

I've taken a while to get back because the car went in to be checked. Guess what: they couldn't find a thing wrong! In fact they couldn't really smell what my wife and I can.

To recap, the smell is of a low level 'fumey' style. It's like a slight whiff of exhaust fumes. Frankly it's difficult to describe. Also, to be fair to the garage, the fact that it comes and goes and changes in strength doesn't help.

I can make it go away by altering the heater settings and if the heater is set to cold and reset to hot, sometimes it doesn't come back!

However, when it's there and you're exposed to it for a while, you can start to believe it's quite noxious.

I was interested in GR's comment: '....a newly painted radiator smell. Could you enlarge upon it GR?

It might simply be that as this is my first 993, I'm looking for something that's present in all off them.

Otherwise, who might be the best font of knowledge to diagnose this in the North?

I really need to get this sorted 'cause my wife doesn't want to drive in the car until it's fixed: or worse!

Cheers,

Chris



 
Hi Chris,

I sometimes have a smell of 'fuel' when I get in the car in the morning but it quickly clears. I also get a smell, not fumes, but the kind of smell you get when you open the engine lid and sniff around...kind of an engine smell!

I have had mine checked a couple of times and the carbon canister was changed. No real difference, all pipes good and all seems to be normal!

I would suggest if it is a 'real' fumes smell that is wrong but if it is kind of 'hot engine' smell then I think a lot of us get that!

Cheers,

Mark
 
If with the undertray off you can see no oil at all (look at the plastic valve covers, chain covers and oil return pipes) then I'd have a good look at the heat exchangers. Do they look really old and rusty? If so they may be compromised internally. If it goes away when you adjust the heating to cold, it's definitely to do with the rear ot the car.

How old is it? There are myriad pipes underneath connecting the system, they need to be secure and not perished. Take it to a Porcshe specialist, they'll know right away whether it's normal or not.

Best of luck.
GR
 
As someone posted earlier, air cooled cars have a distinct smell from the heating system. I'm used to it as i was brought up on air cooled Beetles.
It is difficult to describe. It's a warm engine smell rather than exhaust fumes.

pp
 
ORIGINAL: Pickled Piper

As someone posted earlier, air cooled cars have a distinct smell from the heating system. I'm used to it as i was brought up on air cooled Beetles.
It is difficult to describe. It's a warm engine smell rather than exhaust fumes.

pp
Click to expand...

Exactly,I was brought up with my Dad owning Beetles,and its exactly the same smell........I found it quite nostalgic actually when I got my 993.
 
Hi,
Just wanted to say thanks for the replies. The warm engine smell is exactly it. Seems like it's normal. What a relief after so long trying to trace it.

Cheers,

Chris
 
That 911 smell I think is oil (as they all leak somewhere...) vapour. Even a splash when filling will find its way to the exhaust and burn and that smell once in the heating system seems to stay there.

I always feel reassured by the smell as it means that nightmare wasn't real and I sold the RS for a GT3!
 
To take this thread a stage further, I have been looking for a reason why my C2S has suddenly started to have the smell of a rather bad farmyard coming in the vents. This is hot or cold. I have had a look at the pollen filters and even tried running the car without but the smell persists. The filters themselves seem to have actually absorbed the smell as you can smell it on them. It is almost as though something has died in the system. No aircon at the moment as the gas has gone again but this shouldn't affect the situation.
Has anybody else suffered from this.
On a final note I had a 928 years ago that always smelled of curry when the heating was on! Never did get to the bottom of that.
 
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