M104 throttle squealing
 

I am experiencing a squealing noise coming from my 1995 E320 that is inside the engine bay. Every time I press the throttle more than 30%, the sound seems to go away and comes back when I am less than 30%.

Has anyone seen this issue before? Is it some rubber seals that have to do with the throttle body assembly?

Is is a whistling sound? I've had this occur on various carburetor equipped cars. Sometimes it is caused by a vacuum leak on one of the hoses leading to the throttle.

Is this a new sound?

95 should have a half throttle linkage / half motor operated throttle body, I wonder if the internal clutch is slipping.

I took a video of what it sounds like:

https://www.youtube.com/watch?v=l6J_lOHDHWc

It's not the smog pump, seems to be coming somewhere around the throttle body, but I don't know what exactly.

Sometimes the actuator motors get noisy. I've got a two year old throttle actuator off my wrecked '94 E320 w/ASR in case you end up needing to replace yours......

Sometimes the small PCV hose that goes up to the plastic intake from the lower plenum can split and make some weird noises. I would assume you would have some driveabilty issues how ever if that was the case.

Is there supposed to be a hose at this nipple I found between cylinders 4 and 5?

http://i.imgur.com/tSbw9z7l.jpg


Found a reference to this on a Thai posting, but no answers:

http://www.benzowner.net/forum/showthread.php?t=78775

http://i1068.photobucket.com/albums/...O4h-Q60_57.jpg

I'll have a look at some of my cars / spare engines and let you know.

my 99 has a rubber plug there.

as these cars age,I just use common sense,and block off this emision crap

You have a vacuum leak, use a piece of hose and put it to your ear, aim near the leak it will help you identify where the general area its coming from and report back, it could be the hose under the intake , breather type hose, or check valve to brake vacuum line, the spigot dosent get a hose in your picture

Last time i had this it was the exhaust manifold gasket .But thats on the other side of the engine . May be pully bearings ,or alternator bearing .Sucking air some place . Or vacumm .

It was for sure a vacuum leak of some kind. Car idles rough when it starts running in a closed loop mode.

I took the intake off to look for anything broken, found this:

http://i.imgur.com/ApR2a3zl.jpg

I'm pretty sure that's the problem. I'll replace this, along with the other long hose, the intake manifold gaskets, fuel injector rings, and see what happens.