Strange Engine Squeal on '95 ti Automatic

[cslayman]

Hi,
I've got a strange engine squeal on my '95 318ti automatic with 240K miles on it. It sounds like the accessory belt, but I have removed both belts (AC and waterpump/PS/alternator) and the squeal continues. So it's not any of the pulleys.
It only happens when the engine has warmed up. It also seems to be related to throttle - it squeals on coast down but not as much on acceleration. It also squeals it idle and does not matter if the transmission is in Drive or neutral.
It sounds like a genuine squeal and not a vacuum leak. Any ideas?

Thanks,
Charlie

[xxxJohnBoyxxx]

Originally Posted by cslayman

Hi,
I've got a strange engine squeal on my '95 318ti automatic with 240K miles on it. It sounds like the accessory belt, but I have removed both belts (AC and waterpump/PS/alternator) and the squeal continues. So it's not any of the pulleys.
It only happens when the engine has warmed up. It also seems to be related to throttle - it squeals on coast down but not as much on acceleration. It also squeals it idle and does not matter if the transmission is in Drive or neutral.
It sounds like a genuine squeal and not a vacuum leak. Any ideas?

Thanks,
Charlie

Maybe your cat converter is clogged and needs replaced due to milage..

[b.u.ti-ful]

If it squeals while idling in your driveway, you might be able to take a length of one inch pvc tube and use it as a stethoscope to close in on the noise location.

Or, it could be swine flu.

[cslayman]

Nope! Not the catalytic converter.

[cslayman]

I got under the car and it is much louder from the bellhousing area than the front of the engine. But I'm trying to imagine what would make a sqealing noise in that area. It's only the torque converter.

[cslayman]

It turns out to be the crankcase breather (or vent) valve! Go figure! Check out "Loud Squealing at Idle" from July 2007.

[b.u.ti-ful]

That was lucky!

[cslayman]

You're darn right! ;-) I was afraid it was something like the flexplate and ring gear that would require removing the transmission! I never would have guessed the breather valve if it weren't for the thread on this forum.

It looks like that when the breather valve breaks, there is direct intake manifold vacuum into the crankcase. I think the air drawn into the oil filler cap vibrates the metal at a high pitch. Like I said, never would have guessed it!

[cooljess76]

Cool man, that vent valve is the culprit of all sorts of noises and mechanical issues. It should be quiet under normal operation, and you could usually feel a little air blowing out of the slit on top. Some signs of faulty CCV's include a loud hissing, irregular or high idle and as you've experienced, a loud squeal. Another good thing to do, when/if you remove the valve cover(lets say to replace the valve cover gasket for instance), Hose out the port on the back of the valve cover where the vent hose connects to it. I use brake cleaner and a pick-like tool or Q-tip. This port usually gets clogged up with gunk and buildup which also causes mysterious problems related to the CCV. Glad you got things sorted out, hope this helps anyone else experiencing these symptoms.