Oily gunk buildup on the underside of the exhaust
 

I've only just noticed this oily gunk buildup on the underside of my Invidia Q300 exhaust. It was much worse than in the photo of the muffler as I had run my fingers through it already - http://imgur.com/a/RIsxr I've since cleaned this up as much as I can after I saw this last night.

This is the first time I've checked under the exhaust ever since I installed it about 5 months ago. My previous exhaust never had anything like this before.

Little back of a backstory here: http://www.ft86club.com/forums/showthread.php?t=118134

I'm pretty sure the turbo (journal bearing) has been burning a little bit of oil. As for how long this has been going for, I can't really say but it's getting more and more noticeable now. Is the oily gunk buildup tied in with a possible leaking turbo? How does it appear on the outside (bottom) of the exhaust?

Still smokes a little bit when driving casually and you can notice the smell a lot more when I give it some throttle. I originally thought this was condensation since it's quite cold here in Australia now but it's definitely light blue smoke. I've been in contact with the local turbo kit manufacturer so it's definitely getting looked at. Could it be as simple as just requiring a larger oil drain? Not sure if these symptoms point in that direction. Can't see any oil leaks within the engine bay. My guess it's being pushed through the seals and getting burned?

Bummer. So, if you suspect a journal bearing being the cause, how do explain oil residue bring on the outside of the exhaust? Blue smoke certainly is an indicator of burned oil or a rich mixture, but are you basically thinking that there's so much unburned oil in the exhaust that it's leaking through a flange gasket and covering the outside of the exhaust? Do you have oil collecting on the inside of the exhaust, too? If so, then maybe the journal bearing is the cause, but the image you've uploaded shows the outside of the exhaust covered in oil, not the inside. Could you have an oil leak upstream either at the oil pan or turbocharger, and airflow under the car is blowing it onto the exhaust? Is the entire bottom of the car covered in oil, too? If it's truly coming from the exhaust flow itself, then how confident are you that your tune isn't running rich?

Well, Sh1FTy, I'll buy into @RJasonKlein 's theory that your car has a major oil leak, upstream and outside of your exhaust.

Back-in-the-day, I would suspect a rear main bearing crankshaft seal as what is leaking.

I would suggest you get your machine up on a rack, clean up the oily parts, fire that sucker up and look for the source of the leak.


humfrz

It definitely looks to be an external leak. Have you noticed your motor using a bit of oil? With that amount of oil under the car you should be able to follow the slick forward close to its source. If that doesn't narrow things down it could be any number of things but I would start with anything oil related that was touched during the turbo install, like the sump or the turbo feed lines.

It does look like a little shiny and moist looking through the exhaust tips. The rest of the bottom of the car looks fine. The oil seems to be just local to the muffler and a bit of that first pipe that connects to the entry of the muffler so I'm little puzzled.


I've checked my dipstick and the reading has hardly dropped, maybe 1-2mm over the last few months so it's definitely not burning a lot of oil.

If the oil trail doesn't move further up the car I'd be looking at your diff for leaks as it's the closest oily thing to your rear muffler. Did you put the car up on jack stands or just look under?

I had a look under tonight after a drive home. I can see an oily substance trickling slowly from the vband clamp of the Q300 down to the lowest point of the exhaust and pooling up on the outside. My guess is that it's been happening for quite a while and it's been accumulating on the muffler after it gets sprayed once it leaks out? Checked under the diff and it looks fine.

Hopefully after a re-tighten and the source of the oil leak is fixed it shouldn't happen again. Is there anything I can apply near the vband clamp to close up any gaps?

Your exhaust system contains only exhaust gasses, not oil. The oil you are seeing is most assuredly coming from somewhere ahead / above that v-band clamp.