1995 993 smoke in heater system

djbennett · 01-08-2008, 04:54 PM

I have a 1995 993. I get smoke in the car interior intermitently when using the heater in cool weather. Primarily this happens if the car is sitting idling at a traffic light or backing up. I have checked the valve covers and have replaced one valve cover and gasket. I do see oil seeping from the timing chain covers and suspect this may be the problem. The oil leak is not bad since I only consume about 1 quart every 1000 miles.

Is it possible to remove, and replace both timing chain covers and gaskets without removing the engine?

Are there any other oil leak problems which would cause this problem?

What is the best procedure to use to identify the location of the oil leak?

I would appreciate any feedback on this issue.

Thanks

kang · 01-09-2008, 07:33 AM

This won’t help with finding the oil leak, but you can remove the heater ducts and clean them out. I did this to mine, and the normal oily smell you get with the heater on was greatly reduced. Perhaps you’ve already fixed the leak and all that remains is to clean the residue from inside the ducts.

djbennett · 01-11-2008, 02:24 PM

Thank you for the response. Right now the car is in storage, so in the Spring I will do that.

jimmcc · 01-11-2008, 03:45 PM

Another possibility is that the oil is dripping on the heat exchangers and then being sucked into the engine and in the freah air system. I've had that happen in my '95 993 as well as cat stink when it fires off on really cold days and I stop at a traffic signal before as the cat is warming up.

I have an early production 95 and am not sure if Porsche made the change in the 95 models but I know by '96 the heater fresh air intake was moved to bring fresh air in through the fresh air opening under the tail.

As for the leaks, they will let you know easily where they are originating. Get the car up in the air and take a look. Most of the time it will be the lower valve covers and the chain housing cover gasket. If you have it parked long enough with out cranking the leaks will be directly above the spots on the floor unless deflected by the heat exchanges which in that case the oil will be on top of the exchanges waiting to be heated by a hot engine.

How do I know these things? Just completed replacing the lower valve cover and chain housing gaskets at 100k. The valve covers are easy, the chain housing covers are a bear as access is difficult, more so than it looks. My engine looked stripped at mid-point in the process and I'm glad I didn't start the process DIY as I had intended. You can do it DIY but just plan on having pleanty of time, patience, tools and oil clean-up available.

Hope this helps.

Jim