"Hissing" sound coming from engine
Thread Starter
Intermediate
Joined: Oct 2005
Posts: 36
Likes: 0
From: Louisville KY
"Hissing" sound coming from engine
There is a slight hissing sound coming from engine bay is the best way to describe my problem. Sounds like its coming from the back of the engine and between the firewall. I can't really fit my hand all the way back there, but couldn't find a vacuum leak. I pressed down on the intake and it got a little quiter. Could it possibly be a gasket leak from the intake manifold. Anybody else had this problem, please let me know. Thanks for your time.
Melting Slicks
Joined: May 2005
Posts: 3,394
Likes: 12
From: Leon Iowa
St. Jude Donor '06-'07-'08-'09
Originally Posted by liqwid_vette
There is a slight hissing sound coming from engine bay is the best way to describe my problem. Sounds like its coming from the back of the engine and between the firewall. I can't really fit my hand all the way back there, but couldn't find a vacuum leak. I pressed down on the intake and it got a little quiter. Could it possibly be a gasket leak from the intake manifold. Anybody else had this problem, please let me know. Thanks for your time.
Drifting
Joined: Oct 2004
Posts: 1,621
Likes: 6
I have the same noise, I understand that there is a vacuum line behind the intake and the only way to get to is remove the intake, also pressed on intake and it seemed to bet a little quieter I tightened intake a little from inside out but didnt seem to help a few bolts were looser than I liked. torque to 15lbs
Instructor
Joined: May 2002
Posts: 187
Likes: 0
From: Cumming Georgia
That little vacuum line attached at the back of the intake is a likely (and the least cost) candidate to check first. You can probably fit your hand on the back right (passenger) side of the intake and touch the outlet to see if you can hear the noise change. If this proves impossible, you can always follow the procedure for changing out the oil pressure switch which describes how to remove the intake and reassemble it including that little line.
Team Owner
Joined: Nov 1999
Posts: 26,679
Likes: 17
From: This vette goes to 11 Milford MA
St. Jude Donor '03-'05
You obviously have a Cobra infestation.
Either that or its the vaccuum tree like everyone else suggested.
Its got a big fat hose going to the brake booster and a little slip on 90" elbow goin to the climate control. Its a PITA to squeeze your hand in but its do-able. On mine, the area around the tree was cracked and we pulled the itnake and sealed it.
Either that or its the vaccuum tree like everyone else suggested.
Its got a big fat hose going to the brake booster and a little slip on 90" elbow goin to the climate control. Its a PITA to squeeze your hand in but its do-able. On mine, the area around the tree was cracked and we pulled the itnake and sealed it.
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Thread Starter
Intermediate
Joined: Oct 2005
Posts: 36
Likes: 0
From: Louisville KY
I appreciate the help guys. I will check that out when I get it out of storage soon. Just didnt really want to take it to a dealer, if it's going to be an easy fix. Thanks for the pic reference connecticut, that helps out alot
Tech Contributor
Joined: Dec 1999
Posts: 32,910
Likes: 2,402
From: Anthony TX
CI 6,7,8,9,11 Vet
St. Jude Donor '08
Here is what the back of the manifold looks like:
There are three areas that could be leaking. The brake booster line, the HVAC vacuum line:
Or it could be leaking from the entire vacuum fitting and vacuum sensor that connectcs to the manifold! Your best bet is to get a mirror back there and see if yopu can see if there is any thing loose.
BC
There are three areas that could be leaking. The brake booster line, the HVAC vacuum line:
Or it could be leaking from the entire vacuum fitting and vacuum sensor that connectcs to the manifold! Your best bet is to get a mirror back there and see if yopu can see if there is any thing loose.
BC