Own a 79 300sd (w116) Mercedes Benz with 192,000 miles. Today I noticed an "air gushing" very load noise that sounded much like "Air Bags" coming out of my car. My coworker, parked next to me, also heard the noise and rolled his window down and asked if the noise was coming out from my car or his car. I also heard the air release and suspected it was coming from my car. Just before I heard the air noise my car had been warming up for about a minute when I decided to floor it while in Park. I floored it to get my coworkers attention and to let him know that I was going to pull out of the parking lot first. 2 days ago I thought I heard a very similar noise coming out of my car but I figured it was a car driving on the opposite side of the road. I dismissed the noise and continued driving. 2 weeks ago I came to a stop and then immediately floored it and noticed that the car was getting louder and reving higher but not increasing in velocity. It was a weird feeling to the car and had never experienced that build in pressure without having some kind of increase in speed. I thought it might have been the tranny but did not feel any issues with the shifting right after. The tranny shifted normal like always and have not felt any problems in the tranny shifting since. I thought it could of been the turbo spooling to quickly and somehow not responding due to some kind of protection mechanism(probably completely wrong on this). What could make this "Air Bag" air release noise. Its very loud. The only other thing I could think about was something vacuum related. Has anyone experienced this? About 1 month ago I turned the ALDA screw out and installed a boost pressure gauge between the manifold and ALDA. I get 10psi max when depressing the pedal all the way and get approx 5 psi while cruising. I did not check to see if the pressure gauge needle moved when flooring it in while in PARK. 2 forum members think it might be the wastegate and the other thinks it could be a leak between the manifold and the turbo. Please advise

Check the big U-shaped air intake hose that runs into the turbocharger.

I found on my w116 SD the hose got hard with age and had warped a bit -- it could easily be knocked off the mounting at the turbo inlet. That will produce the noise that I think you are describing.

Also there is a flexible sealing ring that goes inside the hose and helps to hold it in place on the lip at the turbo inlet. The ring tends to disintegrate with time and may be long gone. If that ring is missing, it is much harder to get a firm seal when you tighten the clamp, and that increases the chances of it popping off.

I went and got the OE clamp from the dealer, to replace the mcpart someone else had used. It wasn't expensive and worked much better.

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Mac
2002 e320 4matic estate│1985 300d│1980 300td
Previous: 1979 & 1982 & 1983 300sd │ 1982 240d

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