VIDEO Vacuum Leak Sound from Upper Manifold?

savegoodautonfg · Jun 4, 2006

I removed my upper manifold 2 weeks ago to paint it. I got it off no problem.I put it back on and for some reason it was making a vacuum leak hissing noise. then i took if off again checked all the hoses and evrything was fine. i brought it to my mechanic last night he and his friend took 3 hours trying to figure it out. they called me and said it was done. i picked it up went home and it was still tehre. they looked at eveerything and can not find out what is wrong with it any ideas?

also to add... pcv valve was replaced and everytime intake manifold came off new gasket was installed.

Ok, i need help so bad i managed to get a decent video of the noise in here.

Don't pay attention to the booooommm noise its from the crappy camera but near the end u can hear the whistling/beeping noise the best.

http://www.youtube.com/watch?v=DQnbzy55lkY

bill302 · Jun 4, 2006

have you pulled the pvc valve and brake booster line at the booster out to see if you have vacuum at these points and is there a good grommet in the pcv port...and have you tried using starter fluid to locate vacuum leak? and does it backfire on acceleration...you can overtighten intake bolts and crack intake its not hard to do....

86bluecobra · Jun 4, 2006

lol i think you should worry about your camra more then your car. camera sounds worse. you can try using propane or something like that to check where the vaccum leak is exactly. with a tiger torch turn the propane on don't light it and run it around the area you suspect vacuum leak is. if the car's idle picks up you have found the leak. if there is no change in idle rpm there is no vacuum leak.

savegoodautonfg · Jun 4, 2006

bill302 said:
have you pulled the pvc valve and brake booster line at the booster out to see if you have vacuum at these points and is there a good grommet in the pcv port...and have you tried using starter fluid to locate vacuum leak? and does it backfire on acceleration...you can overtighten intake bolts and crack intake its not hard to do....

Pull the pcv valve while the car is running?

and also where is the brake booster line?

86bluecobra · Jun 4, 2006

on fire wall should connect to intake. trace line.

Roland69 · Jun 5, 2006

That's a real good idea with the propane....I always see people spraying brake clean or anything that will ignite but propand should work best.

86bluecobra · Jun 5, 2006

yep so far its the cleanest way i have found also.

bill302 · Jun 5, 2006

savegoodautonfg said:
Pull the pcv valve while the car is running?

and also where is the brake booster line?

ya and see if the hoses have vacuum to ensure there connected properly with no breaks to loose vacuum....

savegoodautonfg · Jun 5, 2006

86bluecobra said:
on fire wall should connect to intake. trace line.

is the brake booster on the vacuum tree on the firewall?

savegoodautonfg · Jun 5, 2006

I'm starting to think its not a vacuum leak

savegoodautonfg · Jun 5, 2006

bill302 said:
ya and see if the hoses have vacuum to ensure there connected properly with no breaks to loose vacuum....

All the hoses are good.

$uperstang · Jun 5, 2006

It's hard to tell from the video what is making the sound. Wish I could see/hear it in person to try and help you! When you took the upper intake off you put all of the hoses right back where they belong right?

savegoodautonfg · Jun 5, 2006

savegoodautonfg · Jun 5, 2006

I've been having this problem for the last month and I don't know what to do anymore.

19stang67 · Jun 6, 2006

Well, i don't have an answer for you, but I am helping a friend chase down what sounds like (from you clip) the same type of sound. If we figure it out, will let you know what we had. Personally, i think it might be an internal vacuum leak, like between runners or something like that. I know, probably reaching, but we are stumped as well.

mkk50 · Jun 6, 2006

in your sig, you have listed a bbk throttle body.
If you are still running it, id also give the throttle body a check, they are known to whistle a little at idle

jgfiveoh · Jun 6, 2006

that sounds like the same problem i had. the noise is even exactly the same. first off if you have a BBK throttle body i'm betting thats what it is. they are somewhat notorious for whistling. so i'll try and save you another month of headaches and running around getting people to listen to it. first whatever throttle body u have u need to back off the idle screw slowly while engine is running taking note of the "whistle" and if it starts to quiet down a little keep going until the noise stops. in the process u might kill the engine from a lack of air. if this happens just turn the screw in a little bit in order to keep it going. also u will need to try unplugging the idle air bypass motor connection to disable it. go back and forth playing w/ the adjustment of the idle set screw on the throttle body as well as dis/connecting the IAC motor until the whistling stops. i'm guessing that the engine will barely be running at this point but thats ok b/c u r just diagnosing what is causing the noise. if the whistle goes away then it is the air going around the throttle body plate that is causing the whistle b/c u pobably had it cracked a little to idle right i'm guessing. and the sound is amplified by the upper intake! trust me your vid sounds exactly like my car did. IF U HAVE A AFTERMARKET CAMu will prob need to by the IAC spacer kit with adjustable set screws to remedy this or u can modify your IAC motor like in the "idle surge checklist" sticky to do basically the same thing. also defintitely run codes to make sure that the IAC is not faulty. much luck and u can worship me if i'm right!

90lxboost'n · Jun 6, 2006

I have a BBK 75mm TB and my car whistles also I bet it IS in the TB mine also sounds like it is coming from the middle of the upper intake, I have a trick flow U/L.

MustangGT92 · Jun 6, 2006

did you check the smog line to the back of the heads???

jgfiveoh · Jun 7, 2006

if you still aren't sure get a mechanics stethascope and take off the end so that all is on it is earplugs and open ended rubber hoses. this is one of THE BEST ways to diagnose vaccum leaks and such. try running from the TB to the upper inake like this and you should be able to hear that the whistle starts in the throttle body and moves into the upper intake where it is more predominant because of the way the upper intake amplifies it.

*VIDEO* Vacuum Leak Sound from Upper Manifold?

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VIDEO Vacuum Leak Sound from Upper Manifold?