engine bay buzzing noise

[Mattcamp]

Andrew,
What happened??? Did you give up? By the way, mine stopped making the noise......maybe the brake-clean trick finaly ended up working. Still, it sure was a P.I.T.A. to pull that thing apart.
I'm sure I'm not the only guy that wants to know what you came up with.......Let's get the update.....
Thanks,
M.

[sus911]

My car does this on the very odd occasion. It almsot sounds like a screach. It happens when I start the engine and I get a puff of blue smoke form the exhaust. Normally the car does not smoke at all.
Could this be the sme symptom?

Phil

[jimi_c]

The Gremlin in the back, the one with the kazoo - he has me pretty far out on the ledge. I'd love an update as well, I'd be excited to know of an economical solution.

[adeihl]

sorry guys.. i dropped the ball... pics and an update tonight

[Mattcamp]

Originally posted by jimi_c
The Gremlin in the back, the one with the kazoo - he has me pretty far out on the ledge. I'd love an update as well, I'd be excited to know of an economical solution.

Jimi_c
You might want to try what I did........at first I thought it didn't work but I have not heard the kazoo in a week.
Pull the valve off.
Pull the top of it off (P.I.T.A.---it's plastic & snapped on but you can get it apart. It might crack a little in one spot but it snaps back on & seals no prob.)
Spray brake-clean all over it...get all that sticky $hit out of it.
Dry it.
Snap it back together & re-install.
Don't forget to mark how you took it off. It is a one-way valve. There is an arrow on it. Pay attention. I almost missed it.
M.

[jimi_c]

Thanks Matt, I might just give that a whirl.

[goober]

Mattcamp,

Yeah, about that little arrow...uhhhm. I, uhhhm, kinda missed it when I took mine out. Could ya take a peek and help a fellow Pelicaner out. Which way does the arrow need to point? Maybe a picture?

Thanks brother.

[Mattcamp]

It points to the front of the car. The arrow is on the side of the bottom part of the valve. sorry, no pic.

[911Brian]

I have been wondering for 2 years on what in the world that sound was. It comes and goes. Now I know! I always thought it was a panel or cable somewhere. Is this even necessary for normal operation?

[Mattcamp]

I guess that depends on what you consider normal operation?
I seriously doubt that Porsche would take the time to engineer a part, then go to the expense of putting the part on all of their cars if the part wasn't needed. I think the car would still run but what would you do with the blow/by and vacume lines? Try the quick fix cheap guy method that I tried. Can of brake clean $3.

[Bill in OKC]

I committed a sin when mine was broken. Actually when I bought the car the control vacuum line was disconnected and laying forlorn along the back of the engine compartment. I found it and found out where it went and masterfully reconnected it. Well the noise started... I thought it was an FM buzz in my new rear deck speaker at first - it changed pitch with the engine RPMs. I imagine not having this valve in operation caused the nasty crap that had formed around the oil filler cap and dipstick that I wiped off at the first oil change - ummm that doesn't look good... I took the valve apart and found the diaphragm was torn. After looking at the price for a new one, I plugged the vacuum line and bridged the two hoses that the valve opened/closed. I guess it works like a full time PCV valve now. I don't have the noise, and my car does not have that sludgy buildup inside the oil tank cap (entire engine?) anymore. I'll probably replace that thing eventually but for now all is well.

[adeihl]

Alright guys... heres the scoop. Forgot the cam at the house.. but will take some pics tomorrow...

I have done some research and found that many times the ambiant air valve hose that attaches to the rear of the throttle body leaks sometimes.

From what i have studied, the ambiant air valve supplies additional air supply to the engine throught the oil tank/intake durning a cold start. Our issue is the diaphram often cracks causing the vacuum not to hold inside the unit. The unit then "flutters" or BUZZES as the diaphram transitions between pressure and vacuum

One might ask, why is this diaphram so large if all it is.. is a simple one way vacuum valve. The valve consists of 2 halves with a diapram in the middle. This diaphram is held with calculated tension based on its size and volume of air it can diaplace when accuated. At a noted vacuum pressure ( is that the correct term???"pressure") the valve opens and allows suplimental air to pass into the intake just under the TB.

This is an issue for us guys. I dont believe the valves existance to be a necessity, although it will aid in achieving a smoother starting car. I didnt get a chance... but will do a few comparisons with it detached/attached.

Bottom line.. there really isnt a quick easy fix... although the necessity of the valve is questionable. It might be a simple EPA bs feature of the engine. save a tree!!!

More tests/info tomorrow... Sorry no happy news yet to report, but i hope my research/findings start some wheels turning!

Andrew Deihl

[Buckterrier]

Good morning Andrew, thanks for the update, yes mine went away but comes and goes also now. Looking forward to a fix no matter what it is.

[Mattcamp]

The new part from Porsche changed to a 1987 and later part # and the hoses and bracket are different..........$60 for the valve, $60 for the new bracket, about $45 for the hoses...........Ouch....Come on andrew, we pre 1987 guys still need your help.

[DRACO A5OG]

I am afraid pre-87's we need to pull the trigger and get a new valve and bracket.

But on the hoses issue can't any hose work as long as it is the correct diameter and length and clamps? My .02

I'm going to attempt to rehab mine and if I fail, I will get a new one. Wish me luck fellas

[Buckterrier]

I've noticed since the end of the last posts, (Jan.), and now mine stopped making the noise all summer. Then with the coming of fall, (colder weather), it's starting to come back. So, cold air has something to do with the 'buzzing'? Anyone else have this happening only in the cold air?

[PSJoyce]

My understanding is that it operates at cooler temperatures, around 50° F and below. The buzzing had been gone all summer, and now it is coming back, forcing me to do something about it.

Paul

[DRACO A5OG]

Buzzing means a fouled up Ambient Control Valve (ACV) or worse a fracture in the ACV or Hoses causing a leak. Time to replace ACV, Bracket and/or 2 Hoses (1 hose is NLA, need to mod one).

Rehabbing the OEM ACV is the other option.

Once I rehab, I will document and post pics. If rehab fails I wil replace the ACV and try to salvage the hoses if possible.

[Buckterrier]

THanks Draco, looking forward to it, (notha winter project)

[Mattcamp]

Definately no kazzoo all summer. It is starting to come back with the colder weather........The humanity!