'95 530i Whistle at Idle

[FiveOJester]

Hello All,

I'm pretty new to BMWs (this is my first and I've had it for 3 months) so I'm not sure if this sound is normal or not. I get a pretty distinct whistle at idle. Not really sure if it remains beyond idle because the rest of the normal BMW engine noises (I think the cam chains that make the whirring/whining noise as you rev) either drown it out or it goes away.

I pulled off the plastic engine cover and rubber insulator and placed my ear in the vicinity of the intake and was able to hear a definite whistle which is not really that loud. The car runs fine and throws no error codes in a stomp test. It idles a little rough, but about what I'd expect from a high-revving, high compression engine. A bit rougher when cold. Is this an indication that the intake gaskets or PCV (diverter) valve might be leaking or am I just being overly paranoid and hearing a normal BMW sound?

P.S. While I was poking around under the hood I noticed some oil below the intake on the front driverside. Looks like I've got some kind of leak so I might be taking off the intake anyways.

[Kalevera]

Hello All,

I'm pretty new to BMWs (this is my first and I've had it for 3 months) so I'm not sure if this sound is normal or not. I get a pretty distinct whistle at idle. Not really sure if it remains beyond idle because the rest of the normal BMW engine noises (I think the cam chains that make the whirring/whining noise as you rev) either drown it out or it goes away.

I pulled off the plastic engine cover and rubber insulator and placed my ear in the vicinity of the intake and was able to hear a definite whistle which is not really that loud. The car runs fine and throws no error codes in a stomp test. It idles a little rough, but about what I'd expect from a high-revving, high compression engine. A bit rougher when cold. Is this an indication that the intake gaskets or PCV (diverter) valve might be leaking or am I just being overly paranoid and hearing a normal BMW sound?

P.S. While I was poking around under the hood I noticed some oil below the intake on the front driverside. Looks like I've got some kind of leak so I might be taking off the intake anyways.

Read the threads by Been-Jammin' in the past day or so -- there's a lot of info in them to be found on this problem. I'd suspect a vacuum leak somewhere in the air delivery part of the intake on the whistling sound. Oil could be from a timing cover (unlikely) or the oil return line under the intake (again, see the posts by "benjamin" and the various replies -- Bill posted a picture that includes said line, IIRC).


best, whit

[Tiger]

Sounds like intake manifold gasket leak... at the same time... change out that ICV.

[winfred]

the intake gaskets on the bottom and front/rear of the manifold are common vacuum leaks, the whistle is probably the pcv plate and a oil leak in the vicinity of the left front could be the breather tube that goes to the pcv plate on the back of the intake. i've had 530s be tough to pinpoint the actual leak due to the leak sealing up when the motor warms up even a little but as the leak gets worse it will start throwing lamda/02 sensor codes with possible weird running as the computer trys to adapt

[Bill R.]

bulletin which describes the whistle as coming from the rear main seal in the back of the block on some. Apparently when the pcv plate fails on some the crankcase vacum is so great that air gets sucked past the rear main seal causing the whistle. This affects the idle as well and the oil consumption. One way to test this is to remove the dipstick so that the crankcase is vented, if the whistle goes away its the pcv plate rather than intake manifold gaskets. If its the manifold gaskets the whistle will be unchanged. Keep in mind that frequently you hear a whistle at the throttle body anyway if you put your ear down to it. Here's part of a bulletin on it.

the intake gaskets on the bottom and front/rear of the manifold are common vacuum leaks, the whistle is probably the pcv plate and a oil leak in the vicinity of the left front could be the breather tube that goes to the pcv plate on the back of the intake. i've had 530s be tough to pinpoint the actual leak due to the leak sealing up when the motor warms up even a little but as the leak gets worse it will start throwing lamda/02 sensor codes with possible weird running as the computer trys to adapt

[Kalevera]

Bill, explain this to me, because I must be missing something/am a slow learner/whatever.

M60 V8s have the dipstick located below the crank case/main oil level. That's why removing the dipstick to check non-vacuum idle doesn't work as it does on any of the 6 cylinders -- no change in the vacuum because the dipstick doesn't have the ability to alter the pressure in the crank case.

So, the question is: does a non functioning PCV allow enough pressure to build up in the bottom end that the path of least resistance becomes displacing the weight equivalent of 5 or 6 quarts of oil (or however much sits in the pan at idle) versus bleeding out the rear main? Were it the case, I would suspect that it would be an oil geyser versus a little air leak.

best, whit

[Bill R.]

crankcase, they are talking about the opposite.. they state the correct vacum is 10 to 15mbar when the valve goes bad it lets too much vacum into the crankcase ... so not that i would know anything about water pipes but if your familiar with how they function.. a vacum will pull air in through the hot oil with no problem just like a water pipe or hookah.... and the whistle that they talk about at the rear main seal is air going into the engine not pressure going out... Now if the valve plugs up so there is no vacum at all then you get pressure build up in the crankcase and thats what causes front and rear main seals to start leaking or fail... volvo's with that stupid flame retarder do this all the time. But back to the excessive vacum in the crankcase, this also tends to pull more oil vapor up into the intake manifold as well as causing the whistle. It goes away as you open the throttle because you no longer have the high vacum present. I'm not sure i'm explaining it clearly enough.

Bill, explain this to me, because I must be missing something/am a slow learner/whatever.

M60 V8s have the dipstick located below the crank case/main oil level. That's why removing the dipstick to check non-vacuum idle doesn't work as it does on any of the 6 cylinders -- no change in the vacuum because the dipstick doesn't have the ability to alter the pressure in the crank case.

So, the question is: does a non functioning PCV allow enough pressure to build up in the bottom end that the path of least resistance becomes displacing the weight equivalent of 5 or 6 quarts of oil (or however much sits in the pan at idle) versus bleeding out the rear main? Were it the case, I would suspect that it would be an oil geyser versus a little air leak.

best, whit

[Kalevera]

Slick. I wasn't clearly thinking through the problem and forgot about PCV operation. Thanks for the explanation -- it makes a lot of sense.

best, whit

[632 Regal]

pop the oil filler cap should do the same thing PLUS you can see the oild spraying off the timing chains!

[Kalevera]

pop the oil filler cap should do the same thing PLUS you can see the oild spraying off the timing chains!

haha...and all over your face! Tried that -- what a mess.

best, whit