Smoke from heater ducts?

[tijnes]

After four years I finally have my '66 running again. It started right up. The motor was not rebuilt but it ran fine then and seems to run fine now. The motor barely smokes from the exhaust not even on startup but after I have it running for a while the cabin fills up with smoke from the heater ducts. The interior is not finished yet so the ducts are open. Smoke is also coming out of the heater flapper boxes.

What causes this? Did mice move in to the heat exangers or is it something more serious?

Thanks
Martijn

[gkase]

Yes... I just went through this...rodents of some type started storing seeds in my heat exchangers because I turned off the heat when parked in my garage (which means the flaps are open)...so...what's happening is that the seeds begin to smoke when the engine heat reaches the right temp...solution is to disassemble until you find seeds and always park with flaps closed!
George

[sballard]

My guess is that some oil leaked into the heat exchangers.

On my car, I once had a bad oil leak on the engine front and smoke would enter through the flapper boxes. Inside of the car looked like something out of a James Bond movie. Obviously yours is caused by something else.

[Doug Steinel]

Wouldn't the smell of the smoke tell you if it is oil or something else being burned? Oil smoke has a distinctive smell.

[kfosburg]

I had a similar problem - it was a mouse house! I ended up opening up every point in the heat ductwork and using a shop vac taped to one end and compressed air on the other, plus plumbing snakes etc... I flushed the heat exchangers themselves with water.

Karl
71 911E

[tijnes]

The smell is not oil. The first time when I started it smelled more like burning plastic. It seems to get a little less now that I've had the engine running a couple more times. Maybe the mice dragged some plastic in there to make the nest?

Martijn

[petrolblue83911]

something is heating up inside or around the HE's, oil is a very clear smell, if it's mice stuff you would see particulates flying by, if you look at the tubes of the HE's from the outside, are they clean, oily, or other?

[gkase]

I think the smell is a definite way to diagnose what's going on...mine had the distinct smell of burning wood (seeds) which pointed to rodent nest or food storage...there was no particulate, just smoke.