Smoke from under dash!

TerryBPP · 04-15-2003, 05:07 AM

I replaced my radio the other day and now there is smoke coming from under the dash when I accelerate. It smells like exhaust smoke. The heater has been disconnected but most of the plumbing is still there. I have functional a/c. I was thinking it may have something to do with the heater plumbing but I did'nt move or remove any thing. Any suggestions before I die of C02 poisioning?

Wil Ferch · 04-15-2003, 05:53 AM

Not C02 poisoning ( carbon dioxide...the fizz in soft drinks).... you mean CO ( Carbon monoxide) poisoning....

If you don't fix your problem, at least get a portable battery powered C0 monitor and put it on the passenger seat. Serious business.....

---Wil Ferch

Jim Sims · 04-15-2003, 05:56 AM

Close the heater valves if they're in place and operational. If not, cap the inlets to the body; but realize that you'll lose any heat to the windshield defroster. Jim

TerryBPP · 04-15-2003, 05:56 AM

.... anyone else.

TerryBPP · 04-15-2003, 05:58 AM

Sorry jim we must have posted at the same time. Where are the heater valve located?

Jim Sims · 04-15-2003, 06:38 AM

The levers to operate the valves are normally between the front seats near the parking brake; they should be fully pushed down to close the valves. The actual valves are located near the front of the engine on the body on either side. From underneath the car look upward following the fabric hose (originally an orange color) from the front of the heater boxes (sheet metal shells around the exhaust manifold) to the heater valves which are mounted to the body. The valves need to be closed (this means the valve vent to the engine compartment is open) to stop the flow of exhaust and smoke forward. Jim

targa80 · targa80's Garage

I will assume that you did not have any smoke coming from under the dash before changing the radio. What does the smoke smell like (exhaust/buring oil, plastic or rubber)? If it smells like plastic or rubber then I would suspect a problem with your radio installation. Acceleration would also mean more output from the alternator I.E. more current more heat more smoke. In this possible case it would not be a direct short but more of an overload of wires. If it smells like exhaust/burning oil then your problem is in the engine compartment.

TerryBPP · 04-15-2003, 07:03 AM

I think your on target with the vent to the engine, jim. I'll have to check it out when I get out of work. Targa80 its defintely exhaust smoke. I first thought it was a buring wire too, but I check it out.

targa80 · targa80's Garage

Since it is exhaust smoke look for oil leaks from the oil tubes to the heat exchangers. I had a minor leak from the left side oil (looking from rear of car) tube on to the left heat exchanger. When I opend the vent for heat on that side it stunk of burning oil real bad. I fixed the leak and flushed the exchanger with orange degreaser and clean water. The problem went away after that

TerryBPP · 04-15-2003, 07:15 AM

I nix the heat exchangers a year ago. I'm running just headers and dual Dansks.

Jim Sims · 04-15-2003, 08:19 AM

Then it's an oil leak onto your headers that's burning and making smoke that is coming in through the heater valves. Shut the valves (vent vanes on the side of valves are open when the valve is shut) or remove them and cap the holes with cover plates and sealant.

TerryBPP · 04-16-2003, 06:26 AM

Just to update:
The smoke from under the dash was cause by a engine oil leak dripping on my passenger side header. Still haven't located leak but I think its either a oil tube or a main seal leak. I'll figure it out tonight.
Its weird though, the leak only occurs under hard acceleration which is making it difficult to track down. Oil presure is still good and there is no smoke from the exhaust either.

targa80 · targa80's Garage

degrease the area that you suspect is the cause of the leak dry it off and dust the area with baby powder. drive the car and check for where the baby powder has washed away from the oil leak.

TerryBPP · 04-17-2003, 06:14 AM

I found were the leak is coming from, sort of. There is a stream running down the passenger side of the motor between the trans and motor, but not on the seal. It is near the oil cooler but it seem like its coming from higher up.
Is it possible that I put to much oil in it and its blowing out the crankcase breather? Any help would be appericiated.

Jim Smolka · 04-17-2003, 06:50 AM

Could it be the oil pressure switch???

TerryBPP · 04-17-2003, 07:30 AM

I just read a previous thread that described my exact problem. It was the oil pressure switch in the thread. Does anyone have a diagram to show me the location? 1976 911s 2.7. Thanks Jim S

Jim Sims · 04-17-2003, 08:31 AM

See:
http://www.pelicanparts.com/911/911_Parts/1974-75/1-1-2.JPG

Item 49 is the pressure switch. Item 39 (O-ring) for the thermostat (item 38) is also a potential "leaker". These are tough to get to on a '76 911S with CIS (I have one of these models) with the engine in the car. The are a lot of EGR parts, air lines and valves in the way. A partial or full engine drop may be required to gain reasonable access.

The drain line from the bottom of the air box also drains at the same place (front passenger side of engine). I would check your oil level; it should be at the midway point (and no higher) on the dipstick with the engine idling at operating temperature on a level surface. Any higher and one can throw oil into the airbox when making high speed right turns.

Cheers, Jim

TerryBPP · 04-17-2003, 11:23 AM

You have been extremely helpful Jim. I did just change my oil the other day maybe I add a little to much. I will also chech the switch.