Hello. My 1998 520i automatic is throwing black smoke from front grill on the bonnet, with burning smell. It happens only when car is hot. I go uphill to drop my son to school about 4 miles. From last one week I am noticing this smoke when reaching school and when I place hand next to grill its hot. But when I come back downhill back to home, no smoke, front of grill normal hot. I tried to check if there is problem with auxiliary fan, left the car with full AC on for half an hour. But nothing happened. AC is working fine however Auxiliary fan didnt turn on. Car is not over heating. Burning smell is like oil or grease burning
The first thing I would do is a quick visual inspection for any oil or fluid leaks near the area where you are seeing the smoke. After confirming that there is nothing leaking onto an accessory drive belt or the exhaust manifold I would check the fans. With the engine cold you need to gain access to the fan blades and turn them slowly with your hands to verify that the spin freely and most importantly smoothly. If you feel any roughness, or if the fans are binding up or sticking at any point in rotation, there is your problem. You say that it smells like oil or grease, but most oil burning will give you a grey smoke. The black smoke sounds like electrical smoke which points towards a fan problem. Let me know if I can be of any more help.
July, 18, 2012 AT 8:34 PM
Yes I have checked the leaks and left a cardboard under the car overnight. There is no leak. Main fan is working freely. I try to move auxiliary fan and it did move freely, however I didnt try the whole circle. I will try that and come back to you.
July, 18, 2012 AT 8:55 PM
I will do a little more research as well. When you are checking the fans, do a quick visual and make sure that the wiring in that area looks ok. There is always the possibility of something not fan related. Let me know what you find.
July, 19, 2012 AT 12:38 AM
PLASTIC "COOKIN'" GIVES OFF BLACK SMOKE
. THIS MAY OR MAY NOT BE YOUR ISSUE
WE DID NOT GET TO SEE THIS PROBLEM 3 WEEKS EARLIER, OBVIOUSLY THE LADY WAS NOT OBSERVING THINGS EITHER. LOOKS LIKE SHE WOULDA HAD SOMEBODY LOOK UNDER THE HOOD AT MINIMUM, WHEN SHE FINALLY ADMITTED IT WAS "SCREAMING" NOT "SQUEAKING LOUD"
I'M NOT SURE WHAT THIS CAME OFF OF.I'VE KEPT IT OVER A YEAR
MAY HAVE BEEN A BMW OR A LEXUS
THIS IS JUST A MILD EXAMPLE OF HOW PEOPLE NEGLECT THEIR VEHICLES
THIS MIGHT HAVE LEFT HER SITTING IN A BAD ENVIRONMENT