Smoke!!! (not from the exhaust, either) - PeachParts Mercedes-Benz Forum

bustedbenz · #1 05-31-2007, 04:20 PM

Drove the 300SDL its usual 30 miles to school this morning with no problem. Shut it off, went inside... waited about two hours, when I'd need it again. Long story short, field trip to the zoo involved me driving myself there so I could leave early. Had 2 passengers.

Cranked up, eased around to the bus lot to load up, left the car idling, air conditioning running (For what that's worth

) windows down because the car had been soaking up sun and the air isn't really working right anyway.

Idled it for somewhere between five and ten minutes while I was standing in the group of people getting directions for the lab we were going to do... went back, got in the car... and things were a tad hazy. Smelled odd and looked odd.

The smell: nothing I've ever smelled before. I wouldn't have been surprised to smell diesel, Rotella, antifreeze, ATF, or PS fluid buring from a hose, etc.... nothing. Also wouldn't have been surprised to smell burning serpentine belt from a locked a/c pulley that I rather suspect is coming. No such luck. Belt and all fluids are fine. The smell was like a cross between rubber smoke and !!! electrical smoke. (Comment made by friend was that "your car smells like a tanning bed" - I have no idea but if that helps anybody, i guess it was sort of like burning oil, just not motor oil)

Within the next 30 seconds, while I still had my sanity about me, I noticed that smoke of some description (not particularly dark, necessarily, but definitely present) was coming out of the heater vents. It was also coming out the vent at the hood right at the windshield... apparently the source of the smoke was under the hood somewhere, and it got into the air supply as well as rolling up the hood and out next to the windshield.

Killed the engine, made up an "out of gas, got to go get the other car" story to the bus driver, and flew around to the parking lot - smoke had already stopped by this point. No idea why. But it sure smelled like the dash was about to burn itself up.

Restarted it, went around the lot, got my mom's Crown Vic and the rest of the day was without incident.

The fun part: I can't reproduce it now. I'm at school for two more hours and then my dad's coming, we're pulling the band trailer to the concert tonight... we could tow it home if we had to but I"d rather fix it and drive it. The problem is, I can't find a problem.

Went out just now (after school) and cranked it, turned on the air, and idled it. (80 degree day, same as this AM) Engine came up to temp, aux fan clicked in and out, nothing abnormal. No smoke. Ever. Drove it around the lot three or four times to simulate driving back to the bus lot, then idled it for another 10 minutes (did it about 10 minutes the first time too). I have yet to see the first hint of the odor or the smoke. But it was very, very, very, VERY definitely present this morning, and I am positive it was coming from my car, that's the only way it could have been rising out of the hood where it was, it's not like I parked on top of a chimney or something.

I have my tools in the trunk but little time and resources... in the next hour and a half, what do I check before I just get my dad to drive it home and let me take the truck/trailer and just hope he makes it.

I wish it had smelled distinctly electrical or distinctly rubbery/fluidy, so I'd know what it was and where it was; I know the smell of every fluid in the car, even while burning. And I've already checked, the oil and antifreeze are there, the belt is on firmly, and the aux fan isn't locked up. I'm at a loss. How do I diagnose this in 1.5 hrs?

rrgrassi · #2 05-31-2007, 04:55 PM

Could be something like rubber or tar from the road found it's way on to the exhaust, or something loose on the engine or tranny was touching the exhaust, and your zipping around the parking lot dislodged it.

Volvo Diesel · #3 05-31-2007, 05:53 PM

You're sure it didn't smell at all like anti-freeze? My aunt's car recently had a heater core go out. After sitting for a time at idle, smoke/steam would come out of the vents, causing the car to haze up. This "fogging" didn't happen if you simply got in the car and drove; only if you let it idle for a number of minutes. Coolant loss was (at first) almost imperceptible, but then the car started dumping it all on the passenger side floor (lovely!). One heater core and trip to detailer for carpet shampoo later, and no more hazy/stinky cabin. However, if you idled it and couldn't reproduce the smoke, and it smelled electrical....perhaps a short in the dash???? Are all the electrical gadgets working in the dash? Good luck--electrical issues are, for me, a nightmare.

Kuhlrover · #4 06-01-2007, 12:16 AM

Is it possible you toasted the fan under the dash? Pull the under dash cover on the passenger side and see if something caught on fire.

TimK

vstech · #5 06-01-2007, 08:52 AM

freon has a oil in it that has a very interesting smell when burning. you may have a leak in your freon lines. (you did say it was not cooling well, and you left it running with the windows down)
John

tompaah7503 · #6 06-01-2007, 09:07 AM

Quote:

Originally Posted by bustedbenz

The smell: nothing I've ever smelled before. I wouldn't have been surprised to smell diesel, Rotella, antifreeze, ATF, or PS fluid buring from a hose, etc.... nothing. Also wouldn't have been surprised to smell burning serpentine belt from a locked a/c pulley that I rather suspect is coming. No such luck. Belt and all fluids are fine. The smell was like a cross between rubber smoke and !!! electrical smoke.

Your description of the smell is similar to what the smoke smells when engine oil drips on a very hot surface in the engine compartment, it doesn't combust but instead vaporizes into light gray smoke.
Makes sense it stopped when you turned the engine off since oil pressure also drops then. Check for any oil stains/drips near the exhaust manifold?

regards,

winmutt · #7 06-01-2007, 10:02 AM

Transmission fluid?

Theurig · #8 06-04-2007, 11:24 PM

Same exact thing happened to me today folks. The A/c on my 1990 420 sel is ice cold, I had been idling for a while, while I was speaking to someone outside the car. Got back in and the same exact smell described was distinct and coming out of the vents. With A/c still blowing Popped the hood and the source of the smoke was right by the main fuse box underneath the brake fluid reservoir by the firewall. I looked there and it was RED HOT, LIKE COAL ON THE GRILL!!! I TURNED OFF THE A/C, and sure enough the RED hot turned off..... I didn't have a flashlight or anything to identify the exact source. I am taking it to the shop on the weekend, It's going to be fun next few days with the south florida sun and no A/C !!!! will keep you all posted. This only happened with the A/C on, when the A/C is off all is well.

bustedbenz · #9 06-04-2007, 11:29 PM

And did you get smoke out of the vents or from the windshield that was sort of a mixture of grey smoke and fairly blueish smoke?

By the way, i've tried every combination of a/c, hot day, cold day, ten minute idling, etc... plus driving the car all week for lack of other options... and haven't been able to reproduce the problem yet. Wish I could... I was planning to take it to Atlanta this week and am now restricted to my mom's crown vic... although it's made several hundred miles back and forth to school since this incident... if it's going to burn itself up I just wish it would go on and DO it so I could find and fix the problem. (I've taken the spare diesel out of the trunk and am carrying a fire extinguisher now)

Theurig · #10 06-04-2007, 11:36 PM

got the smell from out of the vents, the smoke came from the windshield, but the source is definately right by the fuse box in front of the firewall.

bustedbenz · #11 06-04-2007, 11:42 PM

Thanks - at least I have a little more confirmation I didn't imagine it now. I'll look there if I can get it to do it again.

Theurig · #12 06-06-2007, 08:37 PM

Turned out that one of my auxilary fans was seized. With the A/C on and the car idling for a few minutes my mechanic and I watched the smoke form, the area under the fuse box got EXTREMELY HOT!!!! As we watched....., and tried to diagnose; more smoke began to form at the left side auxilary fan, the other was running fine. Disconnected and removed the seized auxilary fan and ran the car again for a while. The area under the fuse box cooled off, and everything ran normal. I go back tommorrow, to get a new Aux fan installed as it was too late to get one delivered.

If your problem was the same; maybe the reason you are unable to reproduce the problem is that something may have been preventing your fan from turning.....???? Again every beast is different but I hope this is/was the source of your problem.

Cheers.