I have gone through the archives looking for topics and found none similar to mine. There were some on gas fumes, not not exhaust related. I have an 88 Carrera coupe with an automatic heater control system. When the car is cold and the automatic heater switch is on, I get a heavy rush of exhaust fumes in the cabin. If the switch is in the off position until the car warms up a little, the anomoly is much less pronounced or doesn't always occur. Does anybody have an idea what may be causing this? I should be able to start the car cold, regardless, of what position the heater switch is in, without getting the fumes. I have checked all rubber hose connections, clamps, etc. All exhaust connections are also tight. Stumped in San Antonio.


Ron McAtee
88 Carrera
Spider911 <img src="graemlins/cussing.gif" border="0" alt="[grrrrrrr]" />

 

I had a similar problem. many suggested
it was the heat exchangers. you can pic
up new ones from partsheaven.com
that didn't end up being my problem though.
i had a little oil leak out of a breather
tube and when it heated up it was sucking
in smoke from that. good luck!

 

Swimwear, This does not occur if the heater is off when I run the car cold. It only occurs when the car is cold and the heater in the "on" position. It does not occur if I start it with the heater switch "off", let it warm up to temperature, turn the heater on and then drive the crap out of it. I guess I'll keep the heater switch off until reaching temperature and then warm up the cabin. thanks for the reply.

 

I have the same problem with my `87. If I start it and back out of the garage with the heater on, it fills the cabin with exhaust. However, I can turn on the heat once I'm moving in a forward direction. I think it's just the fact that the intakes are backing through the normal exhaust cloud from a cold engine. It's not bad at all when it's up to temp. Does this sound logical to the group, or do I have bad heat exchangers???

 

Ellsworth. Exactly what mine is doing. I guess we need to leave the heater in the off position until engine warms up. I don't think it is the heat exchangers or it would occur all the time. Thanks for the input.

Spider911
88 Carrera

 

There are two heater hoses about 8" long on either side of my 88 Carrera, going up from the heat exchangers into the engine compartment (to the blower, I assume). Both of mine had cracks in them, so that when the car was stationary, some exhaust fumes got sucked into the heating system, or at least thats what I think was happening. The hoses are easy to replace, and since doing so I have not had any problems with fumes in the cabin.

 

I don't know if the late 80's 911s have them,but my 76 has heater control valves on each side right above the heater exchange.They open and close to bring heat into the cabin.If you have them which I think you do check them first they are alot less expensive to change.