Burning oil. Need opinions please

[matt_gh]

Hello, so about 2 months ago my beloved b5 blew a big cloud of blue smoke. Blew that way for a few miles were i could turn off and look to see what happend. Couldn't see anything out of the ordinary, oil was fine to. So I drove home an parked her. Smoke was still rolling out after I turned it off and smelled like a deep fryer. Which brings to now. After finally having time too dig deeper I check the usual suspects, valve cover gasket, pulled plugs they looked clean, my 02 sensor is white. But my inter-cooler had oil in it an my throttle body had oily residue on it as well.

Ive been told it could be the turbo or the pcv below my intake man. It should be noted that my pcv valve below the intake man( 90* L shape elbow) has been broken for over a year. I haven't had an issue, could it still be that? Could it be the intake side of the turbo? Im kinda lost as where to start as my plugs looked clean and my 02 is as well. Its burning somewhere though. Any help would be grateful as to where to start.

[Davdraco1]

Sometimes the pcv system gets clogged causing positive pressure. this would cause excess oil to be in the combustion chamber and you would burn it. Other thing to check is the turbo so see if you have a bad seal. Someone correct me if I'm wrong about any of this.

[matt_gh]

So if it is the pcv would i have to pull the whole line and replace /unclog? An with that part missing it does have a bunch of gunk around it perhaps causing pressure inside the crankcase?

[timzcat]

"But my inter-cooler had oil in it an my throttle body had oily residue on it as well"

Likely turbo since the intake side shouldnot have oil in it. Where were you seeing smoke out the exhaust?

[Mattr567]

Can you take off the oil cap while its running?

[matt_gh]

"But my inter-cooler had oil in it an my throttle body had oily residue on it as well"

Likely turbo since the intake side shouldnot have oil in it. Where were you seeing smoke out the exhaust?

Yes i was watching it come out the exhaust. So if its turbo that means rebuild?

[matt_gh]

Can you take off the oil cap while its running?

Haven't tried that. If i can remove it does that mean vacuum leak?

[Davdraco1]

You can have oil in intercooler pipes bc the pcv recirculates blowby and there's oil in that. I wouldn't assume the turbo is bad bc there oil in there.

[seanf86]

sounds like it might be leaking out the turbine shaft seal and cooking inside the exhaust housing causing the smoke, especially the deep fryer smell, get a bore scope camera or something and stick it in the front 02 sensor hole and have a look inside and see if you see shiney black residue, that would be oil leaking into your exhaust housing and burning off in the exhaust.

[Believer]

It should be noted that my pcv valve below the intake man( 90* L shape elbow) has been broken for over a year. I haven't had an issue, could it still be that?

I would start here by replacing this elbow. How old is the current PCV valve in place (located inside the rubber 'T' that connects to that L.)? Might be worth replacing since you'll be there. This can also cause drivability issues as it introduces unmetered air into the system.

From there you could be burning from a number of locations - failing rings, failing turbo seals, failing valve seals. Rings can be diagnosed with a leak down test, the turbo seals were already spoken to and the valve seals would show elevated burning at high vacuum levels.

[matt_gh]

When I looked the front 02 was white and what I could see from the little bit was all white. I'll see if I can find someone with a scope.

[matt_gh]

As far as I know it's stock. Unless it had a change before i got it. Car has 217k I bought it at 177k. So a compression test would be a good place to start? What should the compression be? And lll pull the intake man and look. It may need a whole new bunch of new hoses. This will be a great learning experience! Also would the failed valve seals show oil on my plugs? Cause they are not black.

[AudiholicA4]

As far as I know it's stock. Unless it had a change before i got it. Car has 217k I bought it at 177k. So a compression test would be a good place to start? What should the compression be? And lll pull the intake man and look. It may need a whole new bunch of new hoses. This will be a great learning experience! Also would the failed valve seals show oil on my plugs? Cause they are not black.

the compression should be in the 180~ range the difference between each cylinder shouldn't be more then 20 psi between the highest and lowest reading
if you get more then 20 between two readings it could mean broken rings or leaking valve seals

and with that many miles it couldn't possible hurt the car if you put new pcv hoses on it when i replaced mine the car felt a lot more responsive, now i have the pcv system deleted. so either are good options unless you live in a emissions state.


Sent from my iPhone using Tapatalk