smoke in defrost

[Rickysa]

Did a search and have tried to find something in my books, but I'm stumped. New to me car...when I "turn the heat on" ie, pull the red levers up, I get burning smoke out of the defrost vents. It goes away after a bit, but when I try it again after the car has set for awhile (days), it will smoke again.

Help most appreciated.

[Oh Haha]

What year is the car?

Do you smell burnt wires or burnt oil?

It could be oil dripping onto the heat exchangers or it could be wires in the dash frying.

[E Sully]

That is the beauty of Porsche's design. The air is drawn from the engine compartment through the exhaust heat exchangers, and any oil that has dripped from the engine onto the hot exhaust can be pulled into the cabin.

[DUK]

Also, pieces of leaves in the tubes will catch fire. Ask me how I know.

Take and blow compressed air thru the tubes with the heater handles pulled about half way.

[Rickysa]

You guys are great...sorry about the lack of info on the car (thought it was in my profile..oops) '88 targa.

It's a very acrid smoke...that's what really had me concerned...not an oil smell (but I'm not discounting that, although I don't have any leaks noticeable on the floor of the garage)

My first thought was a fan burning up, but it goes away...and it occurs when the engine hasn't warmed up yet.

[E Sully]

If it smells like electrical check the blower in the engine compartment, or the fresh air blower in the trunk below the windshield.

[GaryR]

I vote for the fresh air blower but mine just emitted nasty smoke whenever I hit the switch (before I pulled the wires, it's a race car)... figured fire would be the next step.

[86 911 Targa]

Before you "dig in",

Just pull the fuse for the fresh air blower.

No smoke, it's the blower.

Good luck,

Gerry

[Tidybuoy]

Originally Posted by Rickysa

New to me car...

Could it be degreaser? My car is also new to me and one of my first jobs was to clean it up - perhaps the prior owner did this with your car.

That said, when I degreased the bottom of my engine & transmission, I must have gotten some of the degreaser into the heater flappers and then into the exchangers. Then after a through rinsing of the bottom of the engine and transmission, I developed a smoky, oily smell whever I use the heater. This lasted about a month or so of daily driving and smelled kind of waxy.

Just a thought......Vern

[Rickysa]

Thanks for the help folks...checking all of the above

[Dave Colangelo]

I would bet it is oil on the heat exchangers. The other week I took a drive with a friend of mine, i put some oil in the car before we left and forgot to put the cap back on the tank. Oil shot out every where, got all over the car behind me (it was a grope drive) and all over my engine. When we stopped to check things out I saw that i had left the cap off, but oil started dripping down not back, cause we were not moving. With the car off this was no issue.

When we got back in the car, I had the heat on, 30sec after start up my friend looks at me and says "dave your car is on fire" there was smoke coming from under the dash and he jumped out quite fast. I popped the engine lid and saw the oil dripping off the heat exchangers and we all started laughing. I had the targa top down so all the smoke went away after a bit, but my car was filled with smoke for a good 5 min. Sounds like you have a similar issue.

I would bet the oil leak is from one of the hoses returning to the top portion of the tank, or possibly the cylinder heads.

Regards
Dave