Rune Grothaug

Hi

I'm having some trouble with oil smell/fumes in my 993 C2 (1994). We pulled the heat exchangers and mix boxes and everything all the way up to the pipe that goes into the longs and threw in the parts washer. Replaced any gasket we found that leaked oil and now the engine is as dry as the Gobi desert. Had it up in the air today to inspect. No oil leaks that we can see.

Now why would the car still reek of (burnt/hot) oil in the cabin? Anyone? I'm at a loss here and would really appreciate any help or pointers I can get.

I've been thinking maybe engine compartment air somehow gets sucked into the heat exchangers and maybe there is some oil leaking somewhere under the fan shroud, but I'm not sure if I can get an endoscope in there to check for leaks. Also I've been thinking that the flex tubes might be leaking but that's not the case.

I guess I need to hear from a bonafide 993 ninja on this. Are you out there somewhere?

Foxman

Are you getting unwanted heat? Hot door sills? Do you no longer get the classic "ping" when you close the doors? If so, there may be a leak with fumes coming in from the heat exchangers. It;s a pressurized system, and if there's a leak the flappers won't close properly. Try disconnecting the hoses that run form the heat exchangers into the flapper boxes.

Railmaster.

A tiny scent of burnt oil just after you have turned on the heat is common if not normal. It shoul be no more than what you could live with but your wife complain about.

If it's worse than that it could be the lover valve covers leaking like they did on my cars, dripping oil on to the heat exchangers turning the drips into smoke sucked into the cabin.

And congratulations to the 1994 993, by far the best model year!

Rune Grothaug

No unwanted heat. The flapper boxes seem to function normally. The car pretty much responds correctly when i push various buttons (defrost, AC and so forth) and the levers also seem to do what they're supposed to. I will however og through all the piping to make sure they're clean (old residue) and are not leaking.

Rune Grothaug

Valve covers, power steering pump, oil pressure switches - they're all dry. No oil on the exchangers. Going to take off the flex tube and stuff a rag into the HE's to check if there's still getting fresh oil in there somehow. They've been through the parts washer three times so they're squeaky clean. We pulled the engine this summer and gave that a good cleaning too... We can't see any oil anywhere. Might be an oil line with a tiny leak that expands when pressures increases and that these fumes get sucked into the HE's. Also - the fan is clean and completely dry (no oily residue on it)

Jay777

Do you get the smells only when driving? On my 97, I always get a slight gas/oil smell after the car's been sitting closed up for a while, but not while driving. It isn't objectionable, I actually kind of like it.

norbtx

That's part of the charm of driving an air-cooled 911!

Jay777

It's not a problem, it's a feature!

Mcgrata

I had oil/petrol smell in my 993 (1996) also. Brought it to Porsche classic in Dublin about something else and mentioned it. John (very helpful) diagnosed faulty air bellows as there was some condensation on the instruments too. Sure enough when he took it off there was a hole about the size of a U.K. £2 coin. Sorted now

Gbos1

Standard feature from Factory

geolab

There are 2 rubber flap valves in the cabin next to the seatbelt rollers on the floor.
One of their role is to depressurise cabin when opening doors.
But when one is broken, the depression suck air from exchangers into the sills and in cabin , from this part
Passenger side flap is within 10 centimetrs from oil radiator lines
Check the one on the passenger side first, since oil smell
part number is 96457204301

fivelitre

If it's petrol fumes you're smelling in the cabin I would guess its the Charcoal Filter (Part No. 99320122103). I've read that these should be changed once or twice in the cars lifetime.

Taken from a UK Forum: It’s basically a cylinder that allows fuel vapour to be stored in activated charcoal before being sucked into the engine through the purge valve when conditions are right. And in the 993 version there’s a mechanical pressure relief valve that allows fresh air through when a vacuum is applied to the other ports, either by the pressure release valve or contraction of cooling fuel.

HTH.

C.

geolab

Hello: the way I see things personnally , The charcoal canister should be leaking for your example. The pressure relief valve is one direction, inside.
If charcoal canister leaks or its pressure relief valve is broken on a 993, 98% of the time the car won't start, and the 2% left of the cases, will have a very very rough idle
for info, on a Rest of the World OBDI system , the charcoal canister functions always without interuption, on an OBDII USA car and any OBDII 993, the system
starts when the O2 sensors are checked by the ECU and the SAI pump stops.
regards

Jweekes67

This is really helpful to me. I have a smell in the cabin and I have just discovered condensation on a dial. Can you just confirm what exactly an air bellows is? I can’t find any information about it. Thanks in advance.
jon

Mcgrata

Hi Jon, I looked at the record from the work done at the time. It says 'replaced defective air intake on engine, no condensation in vehicle now. All operating OK. P993.106.403.00
021533/Air Guide
I was charged about 45 euros ($45) for this part. I presume the numbers refer to part numbers. Hope this helps, Andy