Still blowing smoke, need advice...

[Dave M]

So the 91 525im blows bluish smoke under vacuum conditions. It appears to be getting worse, requiring less 'coasting in gear' to produce the smoke and stink out the area. Last time I brought this up, I believe it was Bill R that said it may not be serious, so I kinda put it on the back burner. I must admit, its beginning to get annoying. The shop that did my cylinder head work a year ago doesn't seem too willing to investigate and believes there is no chance of valve seals being responsible as everything was fresh when the head went together 30,000km ago.
So, what method would work best to determine the source? I have a comp. tester and may be able to find compressed air or have another shop perform a leak-down test. How about PCV system, could it be a culprit? I'd just like to know the probability of it being head related so I can pursue it with the shop, or, take care of it myself if its in the bottom end (less likely I presume?).

Thanks again all.

Dave M

[winfred]

did they replace the valve guides or just the seals? some of the 1st m50s i think had bad guides that wore out early

[Dave M]

They stated more than once that the guides were replaced (brass I believe). Its a recommendation they made when the work was done.

[winfred]

some shops knerl the orignal guides and ream them back to stock size, i doubt this is the case. they should be a bronze alloy

[Tiger]

PCV system can do the same problem..

[632 Regal]

I agree with tiger, if your pcp system isnt working then you will get pressure in the crankcase that pushes oil past the rings, guides etc. If it's severe it can push oil past gaskets too.

[Dave M]

Anything to check first in order to determine whether its PCV related? Thanks again for the advice. Back in a few days,
Dave M

[Bill R.]

pcv system causing the problem...for it to do so you'd have to have a fairly large vacum leak in the engine seals somewhere like a oil filler cap left off.
If that were the case then the car would idle poorly due to the vacum leak.
I would say that you still have bad guides or bad stem seals causing the problem. A compression test won't show this and neither will a leak down test, however they will show bad rings or a bad valve. Some of the vacum gauges sold have a test procedure to determine bad valve stem seals but its not very accurate unless you use a vacum gauge every day on engine and are intimately familiar with what the vacum should look like and can detect small nuances in the gauge..... Almost all mechanics out there don't even have enough experience with this to tell, myself included. The best way to tell is to pull the intake manifold and inspect the valve stems for excess oil, there should be very little there... Ask Jeff N.







So the 91 525im blows bluish smoke under vacuum conditions. It appears to be getting worse, requiring less 'coasting in gear' to produce the smoke and stink out the area. Last time I brought this up, I believe it was Bill R that said it may not be serious, so I kinda put it on the back burner. I must admit, its beginning to get annoying. The shop that did my cylinder head work a year ago doesn't seem too willing to investigate and believes there is no chance of valve seals being responsible as everything was fresh when the head went together 30,000km ago.
So, what method would work best to determine the source? I have a comp. tester and may be able to find compressed air or have another shop perform a leak-down test. How about PCV system, could it be a culprit? I'd just like to know the probability of it being head related so I can pursue it with the shop, or, take care of it myself if its in the bottom end (less likely I presume?).

Thanks again all.

Dave M

[Dave M]

Not good news. I'll be pulling the intake (try to take photo if possible) and talking to the indy if stems/seals are suspect.
Thanks

[winfred]

that was my thoughts


pcv system causing the problem...for it to do so you'd have to have a fairly large vacum leak in the engine seals somewhere like a oil filler cap left off. The best way to tell is to pull the intake manifold and inspect the valve stems for excess oil, there should be very little there... Ask Jeff N.

[MBXB]

Could it be the cyclonic valve? (Cheap POS part, PITA to change)
When this happened to me it looked like my car had turned into a mosquito control unit. Luckily it was still on warranty. I had thought the same thing: seals/ valve guides/ broken ring(s).

[winfred]

m50 don't got one


Could it be the cyclonic valve? (Cheap POS part, PITA to change)
When this happened to me it looked like my car had turned into a mosquito control unit. Luckily it was still on warranty. I had thought the same thing: seals/ valve guides/ broken ring(s).