ATTN M.B.DOC: Turbo whistle thread question

M.B.DOC, I saw this thread, in which you said that some '85 models had problems with the air recirc. component of the turbocharger system that would cause whistling at certain RPM's:

http://www.peachparts.com/shopforum/showthread.php?threadid=4486

I'm experiencing the whistling problem, and was hoping you or others might be able to shed some light on this. Thanks!

Chris Straut
'85 300D, 92k

[stevebfl]

The 85 model has a pop-off valve on the intake sort of like the waste gate on the exhaust. When the throttle is to the floor and released the slowdown of the motor causes the air to back up on the turbo and slow it down. The pop-off allows the back pressure to by-pass.

The device is at the front of the intake, near the top of the motor, easily accesable. Try pulling the vacuum line off and pluging it. The whistle will go away. I presume it has to do with the transducer that controls it. Some are worse than others.

Thanks for your reply. Is that a permanent solution, or is there a part I should be replacing? Don't want to do damage to my favorite car

[stevebfl]

This is not a fix, just a diagnosis of the noise. I don't see any problem with it disconnected except for maybe turbo life, but I only fix them I don't design them.

I wouldn't be surprised to see a good clean-up be of great help here. I have never had anyone so annoyed by the noise that they wanted to pay for a full diagnosis so I don't know the full answer.

I tried your suggestion this morning and did not experience the whistle even once on the way to school. I'll wait until this afternoon when it's warm out for the final test, but it looks like you've diagnosed my problem What exactly should I look at cleaning out? Thanks for all your help.

[mbdoc]

Steve is 100% on answer. The problem is a DESIGN problem not a build-up in the housing. 15 years ago there were repair parts available, now you must buy complete turbo to repair OR disconnect vacuum. I'm sure the EMISSION people won't come looking for you because of it.

Thanks for all your help. Do you think disconnecting the vacuum will cause any permanent damage? I want to have this car for a long time and don't want to buy a new turbo in a year or two because I plugged a vacuum line

Thanks!

Chris

[stevebfl]

Well put it this way, I have a number running around with BBs in the line (as a temp repair). Probably as long as ten or fifteen years.

[GregS]

I found this thread during a search and I'm just wondering if these pop-off valves were only installed on the '85 300d? I had what I thought was an '84, but it does have this valve on the intake (and the annoying loud sound it makes), so I'm wondering if my car is actually an '85 even though it is registered as an '84.

Thanks,

Greg

[RunningTooHot]

Well, this answers a few questions that I posed a few days back.

http://www.peachparts.com/shopforum/showthread.php?threadid=19274

Greg S. – If your car is a California version, like mine, it also has this valve. They were apparently installed on the 1984 California cars, and then in 1985 on all U.S. cars.

[engatwork]

so I am going to leave the bb out.
thanks,