shot heat exchangers?

[JayJ]

I have had this constant greasy film on the inside of my windows and have been told it is because of my 30 year old heat exchangers.I disconnected the 4 hoses that are connected to the system, but still seem to be getting the film. While Im looking for new heat exchangers, how can I prevent this film from entering the cab. I do have a fair size oil leak wich might be contributing to the oily film?

[Jens Wendorff]

Basically, you will get the greasy stuff in every car when switching on the heating. Its everything like burning off dust, futile ingredients of all plastics, things from outside etc... With the introduction of fresh air cleaners in modern cars, the situation has improved, but is still existing.

On air-cooled cars like P-cars, this is much more a problem, as you push air into the cabin which has to run nearby hot parts of the engine, plus the air is soaked in near the engine wher a lot of oil etc. is.

On a 30 year old 911, I assume that more than once there has been an oil leak, leading to sucked in oil.
Removing & cleaning the heat exchangers from the inside (brake cleaner, pressure washer) may help, if much gung is visible.
But you will not be able to remove the oily smell/residue completely out of the system, as the gunk has also found its way through the whole heating pipework.

If you have any sort of oil leak near the fan (e.g. Oil temperature sensor/pressure sensor), fix this first and it will improve the situation.

Replacing the heat exchangers will only help it the old ones are rusted through, providing a contact between exhaust fumes and heating air- but in this case you MUST REPLACE them immideately for your own safety! CO can KILL YOU! (But thats the stuff you don't smell).

Jens