RAWE55

My car has developed what seems like someone has crept under the hood and put some Garrets with blow off valves into my engine. I have been trying to capture on video what i would like to describe a typical blow off valve (cchhhhh) noise when i let off the boost early around 4000rpm. Last i checked the car was supercharged, cant see any blow off valves on the surge tanks, quick look at the manifold confirms no turbos. So seems like ive developed a boost leak somewhere.Fairly sure the bypass wouldnt blead off boost with such an audial. Doesnt happen often, car builds boost right through the rev range no worries, othertimes when i let off she hisses, i logged just above 14psi of boost the other day, 600ft above sea level so im right on par where it should be.. Thoughts guys? Im at a loss. In hopes i capture it tomorrow ill post up.

C32owner

Man so glad someone else has experienced this because I thought I was hearing things once. I say once case that's literally the only time I ever heard it on my ex C32,was modded with code 3 pulley and a few other bits, but remember one particular morning the engine was still cold and I never get on it when it's not up to operating temp yet but for some reason that morning I gave it the beans a little... As I stabbed it onto an on ramp to a highway it probably changed gear before 6000rpm but it let off this amazing blow off sound that was the business.. Was awesome.. Thought the same thing as you, huh since when does my car have a blow off or bleed air valve of sorts... Anyway could only think maybe it was cold air cold engine and over boost somehow that escaped somewhere... Never heard it again and I had that car for 6 years...

efiftyfizzle

Interesting... my car makes a blow off valve type noise but it doesn't seem to have anything to do with boost. It sounds like it comes from the suspension. I can only really hear it when I have the windows down.

typhoon43

Is it possible you're hearing belt slip instead of actual pressure release?

Denroll

Probably because your ricer-self forgot you installed this:

Toadster

it's your suspension leveling itself..

Enigma94

I've heard the same thing on my C32, it happens every time I let off the gas even if I'm not into the boost much....it's not loud at all and you really have to listen carefully to hear it though.

RAWE55

Could very well be belt slip, i dont find any belt powder at all though, so i never really thought about it. We do own a few prime movers in our line of work, never thought the airmatic in a benz would follow suit by leveling itself out especially at high speeds. Ive seen the car do it while stationary, the prime movers do the same, they are however electronically controlled.
It is that same distinct sound, yet it happens right at high rpm when i let off the gas. Not ruling anything out at this stage, will take a little more investigation.
Hahaha DR, the younger generations coming through arent allowed to drive turbo cars unless they are turbo diesel down here in Melbourne. Power to weight ratio restrictions also. They end up with blow of valves on turbo diesel trucks. I distinctly remember sitting in traffic and this one kid kept spooling the turbo to let off his upgraded (ppssshhtttt) blow of valve then slamming the brakes hard with heavy traffic. Did it every time we crept forward a few metres

RAWE55

Found this a while ago and saved. Something like this has been discussed a fair bit on the forum. Particularly surrounding the FSP. Guess my car wants one more then i do

LNDMISSL

+1

I hear mine all the time

Toadster

yup, every morning at the first stoplight about 1/2 mile from my house

chinatownabc

I have the same sound on my e55 only happens in first and 2nd gear around 3k rpm when I release the gas pedal quickly and suddenly. Anyone have any idea ill try to get a video soon

kponti

I get one too...here is the kicker, I have the BC coilover and Star turned off the Airmatic system

Havoc

I hear it as well..

You can hear it on this SLR 722 GT right after the gas peddle is lifted..

uraberg

That sounds like belt slip to me.

Havoc

Does the belt slip when you decelerate though??

Kinda hard to tell what it is since this thing makes such a racket. Sounds like the brakes squeak when entering that one curve..

I mainly posted it because I like hearing this beast!!

uraberg

If the magnet is a little late, releasing the SC pulley, I think it is not unreasonable to have the SC still spin, while the engine is decelerating, and thus getting a little squeak.

Havoc

I can see that happening..

I wonder if guys with belt wrap kits hear the same??

2000UZJ

It's probably the bypass valve opening right when you let off the throttle so it's not compressing...sorry...kompressing air.

My question is why does my car sound like a gunshot when I go WOT at high revs? It has this loud pop (2nd gear, 5,000RPM full throttle). I love the pop sound. SC already engaged.

Go to 1:45 and listen right when I get the gas.