Hello everyone. I'm having an issue with my 2005 a4 3.0. Just bought the car a little over a month ago and it seemed to be in near perfect condition. ive always noticed a weird burning kind of smell when i drive the car for long distances but there never seemed to be any problems relating to how the car ran so i ignored it. just today i noticed a really bad burning smell and when i popped the hood there was smoke coming from the passenger side of the engine bay almost looking like it was coming out of the air filter box. a guy walking by said it smells like oil. it was really strong and smelled electrical to me. anyone seen this before and could tell me what it might be. the car runs great for the most part, might be a slight loss in power but could also be my imagination, also i noticed the coolant was low the other day but i refilled it and it seems to be in the same spot. any help is very much appreciated

 

You probably have a seal leaking differential lube from rear of the transmission (if it's a Quattro). It can drip down on the hot exhaust. The synthetic fluid they use in these things does have a different smell to it than regular oil when it gets hot and smokes. The rear seal on my A8 drips (I've put a new seal on it but it's still leaking, so I think I need to get a new drive flange) especially when I've climbed a steep grade. It only takes a few drops on the exhaust to really get it stinking... Jack it up and see if you can see where some oil is getting on the exhaust.

 

Thanks for your reply, its going to a specialist to get diagnosed today, I'll post the problem once I find out what it is. How much did it cost for you to get that fixed?

 

Not much since I did it myself while I was doing an ATF change. I can't remember the prices but the seal was under $20. They recommend replacing the bolt that holds any of the flanges on (I don't see why because they aren't torque to yield bolts) and they might run $10. Labor shouldn't be too bad if it's just the seal to the driveshaft that goes back to the rear differential. If it's leaking on the short shafts that go to each wheel, the labor will be more since you may have to completely remove the shafts. Sometimes this requires taking some of the outer ball joints loose at the spindle. However, sometimes there is just enough room to unbolt the inner part of the shaft and work it out of the way enough (or even remove it) to get the drive flanges off to replace the seals. Probably the most expensive part is the synthetic gear oil that you have to use to replace what is lost. Some of that stuff runs $12-15 a liter.

 

Well hopefully that's what it is because from what I researched it could be a bad valve cover gasket or a bad head gasket but I feel like if it was head gasket I would feel it in how the car drives. Not really a big car guy so I wouldn't know either way but thanks for your input, hopefully this doesn't run me too much $$$