Ridin Dirty

Burning oil/ exhaust/ general hot engine compartment smells inside of cabin but only with heat on. It's mostly a burning oil smell though.

Anything specific I should look at? I've had the heater assembly and motor blower fan off before doing other maintenance and I didn't notice anything out of the ordinary. I have aftermarket headers with heat but the smell was there before and after the headers; same goes for valve cover gaskets replaced.

This is just an old smell I'd like to sort.

Thanks again

Joe

bbs993tt

Any drip spots on the garage floor?

LexVan

Didn't you just recently change the oil? Maybe you spilt some during the oil change process.

OverBoosted28

I just figured my car is over 20 years old, the layout of the engine, and deteriorating cabin sealing, contributes to that "smell". Until it becomes a hazard, and not yet excessive, it's just part of the car. :-)

Ridin Dirty

I hear you all and thanks but nope none of those

no oil drip (slight case seep, ever so slight and that's almost best can be expected with these at this age w/o rebuild) that's why i mentioned the valve cover gasket replace b/c that would really stink. just a case seep won't smell b/c it just drips down and not on exhaust

and no, oil changes have no bearing on it

this is just a "thing" that has always been there since i purchased it. bought her in the hot hot summer so more interested in a/c working...didn't run heater

So i could never run the heater...ever.. ONLY SMELLS OF BURNT OIL WITH HEATER ON....using the a/c or vent produces no smell at all.....not a trace.....

hhhhhmmmmmm

PiB993

I have always gotten a unique smell whenever the heat was turned on however it has never been soo bad as to bother me. I've driven long distances with the heater on as well and it never caused a problem for me or passengers.

LexVan

Buy some Zaino Z10. Treat the leather. Goes great with the fast-car-burnt oil-smell.

PiB993

I agree with that sentiment but will recommend leatherique then. Their cleaner and conditioner!

P-daddy

You mentioned you addressed the valve cover seals, but how do the heat exchangers look?
Are they both covered with oil? If enough of it accumulated on the HE or enough oil spilled on the HE, it could seep through the seams and into the headers inside the aluminum housing. (This happened to me this past winter doing valve cover gaskets. A gush of oil poured onto the HE as soon as the cover was removed.) The burned oil/fume inside your HE housing will travel up the 90 degree rubber elbow and eventually into your heat duct circuit. That would explain why you only get the smell with heat on. I would start there.

Edit: oops, missed the part you mentioned aftermarket headers.

Ridin Dirty

Sincere thanks. But this is all Greek to me, heating system that is. I'm a decent shade tree on my 993tt but heating system so boring i really don't know too much. Took off entire blower assembly to discover there is no way this could contribute to smell from top of engine.
I guess it goes from blower to heat exchangers/headers (we ARE calling heat exchangers headers right?) then to tubes to cabin. Smell must be coming from under vehicle. looking at all this upon a cursory glance i'm wondering how could it NOT smell like engine? It appears the 993 uses exhaust to heat the cabin.... this is quote different from a standard water cooled anything with a heater core and all. Going to keep tracing tubing/all i can do.

But if anyone knows where exhaust/burnt engine oil smell can be mixed into cabin heat let me know. And to reiterate this was present before and after aftermarket headers

dumb question cant be cabin air filters? i've never changed em.

thanks again

P-daddy

RD- Please pardon my silly question. Is this 3TT your first air/oil cooled? There’s a hint of warm oil whenever the heat is on. I find it pleasant and my wife doesn’t mind it either. I’m on my 5th 993, and they all have that wonderful aroma (no, I have no leaks). That, and if you have very sensitive Olfactory may explain the issue you’re experiencing. However if you have bad leaks and your headers/heat exchangers are coated with oil, your cabin can smell very oily, not to mention some smoke from the rear when the exhaust gets hot.

Another area to inspect is your Timing Chain Cover seals. Are they leaking? You may have a very slow leak that never end up dripping on the garage floor. As the car is driven, the droplets may land onto hot exhaust/cats thus producing the oily smell as it enters the rear blower.

Ridin Dirty

Thanks, I will check timing chain cover (still don't how this system works but i'm learning)

this is my first rodeo with air cooled but trust me its noxious/really cant use heater at all. well maybe with windows down

Mike J

You can get oil into the inside of the heater box (the box that is formed around the exhaust header) which can lead to protracted oil smells. It may not be obvious from the outside, it might have been for instance the PO spilling oil, or having a major valve cover leak for a protracted period of time.

Usually it will fade over time as the oil cooks out, but it can last years. you can try to clean them - that would involve removing the air feed and exit hoses off the heat exchangers, and shooting brake cleaner as best as you can into the box through the openings, and blowing it out using compressed air. You can also use a degreaser and water. Messy work either way.

Its hard for leaks like a chain cover to get oil into the heat exchanger though, but a good visual inspection might be able to find the source.

Cheers,

Mike