"Fumes" from my windscreen heating nozzles

SerialCarBuyer · 02-21-2011, 03:53 AM

I just took delivery of a 1970 911T. During a drive in cold, wet weather yesterday I employed the woefully anemic heating system to try to keep the interior of my windows fog free.

When I shut down the engine (heat lever to the right of hand brake in the full up position) fumes (for lack of a better word) started coming out of the windscreen heating nozzles. It lasted for about a minute and then subsided.

Does anyone know what causes this? Could it be a problem with the heater flapper boxes?

Thanks, Scott

pete3799 · pete3799's Garage

Probably oil is leaking onto the heat exchangers and when stopped some smoke gets sucked into the engine fan and blown through the heater hoses.

DRACO A5OG · DRACO A5OG's Garage

Get under the car safely and ask a helper to move the levers up and down. When down the flappers should be fully open vs up fully closed. While you are there, might as well lube the flaps and spring. Caution you will smell the lube in the first minute or so.

If you have a oil leak around the heat exchangers the burn off may be sucked in temporarily through the opened flaps prior to use.

SerialCarBuyer · 02-23-2011, 06:53 AM

Gents,

It was in fact an oil leak hitting the heat exchanger. Thanks much for your help.

Scott

bfunke · bfunke's Garage

Not to nitpick but technically a fume is condensed metal vapors.

daepp · 02-23-2011, 07:57 PM

I thought this was normal on an early car...

Seriously, I have to clean the inside of my 72 winshield often. I have suspected for some time that it was a leak in a heat exchanger (s)???

SerialCarBuyer · 02-24-2011, 12:20 PM

I was able to get under the car while on a lift today. It is a small seeping leak from a seal above. It runs down the underside of the heat exchanger and the non-metal vapor containing smell, which I will erroneously call "Fumes", are then sucked in to the heat box and transmitted to the cabin. A fairly easy fix and worth doing rather than putting up with the smell.

SerialCarBuyer · 02-24-2011, 12:22 PM

fume (fym)
n.
1. Vapor, gas, or smoke, especially if irritating, harmful, or strong.
2. A strong or acrid odor.
3. A state of resentment or vexation.
v. fumed, fum·ing, fumes
v.tr.
1. To subject to or treat with fumes.
2. To give off in or as if in fumes.
v.intr.
1. To emit fumes.
2. To rise in fumes.
3. To feel or show resentment or vexation.