In Reply to: 540 guys(gals) - READ this . . . posted by Jason Blitz on October 18, 2001 at 08:29:02:
#5 is the one on the m60 motors. It serves the same purpose as a pcv valve on most cars. Which is positive crankcase ventilation. In other words it uses intake manifold vacum to suck out harmful vapors and combustion byproducts from the crankcase into the intake manifold where they are sucked into the engine to burn. When this valve fails they let too much vacum into the crankcase and the air gets sucked in around the rear seal causing a high pitched whistle or screech at idle or periods of high manifold vacum.
While in traffic a few days ago, my 94 540's check engine light came on and the idle went to crap, smoke started pouring out of the muffler, and it didn't want to stay running - I did what I could to move the car out of harm's way(there was no shoulder) and pulled it into a gas station 3/4 mile away. By this time there was a loud metal/metal screeching noise coming from the bottom end of the motor & I immediately shut it off.
Granted, the temp gauge was normal, no oil lights etc. - The oil was clean, the coolant was clean and I saw no signs of exterior damage. Anyway, I knew the motor had been replaced & thought could this be a spun main bearing? - It sure sounded like it! - Anyway, after a lengthy tow to the dealer(I towed it there because I thought it might be a bearing & maybe they would make good on a replacement motor-maybe) - My car spent the night there and the dealer called to tell me that there was a valve on the back of the intake that went bad(whew-what a relief). The valve caused my O2 sensors and plugs to foul(this caused the check engine light). Anyway, long story short, They gave me an estimate for $480 in parts and $720 in labor - totalling to $1200!!. My service manager there was really cool about everything and gave me the parts list - he knew I had done quite a bit of mechanical work (transmission & A/C) before and told me that if I had time - maybe I should do it myself - I called BMA & they got me all of the parts for Half of what the dealer wanted - I got OEM too!! I'm waiting for the parts to arrive right now(Fed-Ex) & it's not going to take as long as expected.
While waiting for the wrecker to show up and take me home, the General service manager(not my guy) - started talking to me and insisted that I couldn't do this job myself and I didn't know what I was talking about - whatever. I insisted that I did all of my own complete replacement on suspension, brakes, tranny, diff, A/C work in my driveway - he laughed and said that this was FAR harder than any of that!! He went on to tell me that it would take 5 hrs just to remove the valve - it took 1hr!!!
Trying to scare the customer into service . . . BTW, the whole time I was fretting on the interstate with the smoke coming out of my exhaust there was a new E39 M5 sitting behind me - embarassing, but . . .
Anyway, if this problem happens, check the valve on the back of the intake - I'm not sure how to diagnose the valve itself, but the symptoms are as I described above.
Cheers! I'll post pictures later today!
Thanks Bruno for pointing the way to BMA!!