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New Mods....Bad noise.....Please Help!

vetteboy86

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Well I replaced fuel injectors, and put a air pump pulley on the car. The car started and ran fine. I a little rich because I dont have the new tune yet. However the car idled for about 10 minutes before I took it out for a drive. I got about ten miles from home when all hell broke loose.

I hear this noise that is the most terrible squel I have ever heard. I cannot really find anything. It does change tone with engine speed. It sounds like it is coming from the coil area. Also when I apply pressure on the top of the plenum it changes tone slightly. The kicker of the deal is when I turn the motor off the tone stays for about 1 second than fades a little then just quits. It almost sounds like an audible alarm of some kind. Any suggestions before i go tearing into things tomorrow??
 

Achilles

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Is it possible that you have an air leak at the plenum/runner or runner/base, or maybe the brake booster line into the plenum?
 

G Winter

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You installed an air pump pulley. I asume you removed the pump at this time.
How did you handle the air ports ? did you leave any rubber hoses? The exhaust could blow out a rubber hose it you left any.Without the pump putting air through the hoses they could get soft from heat.

Glenn
:w
 
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vetteboy86

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I am kind of leaning toward a vacuum leak, but it is hard for me to believe a vacuum leak can sound this way. The only verification I have is whistling. When you suck in and your lips are just right you get a whistle.

I removed as much air stuff as I could at this point as I do not have my headers on yet. I left the short rubber hoses on the top of the manifolds, but I believe there is a check valve in there preventing exhaust from coming out. Am I correct?

I am going to take the plenum off to make some routing changes with a few vacuum lines, and perhaps install a new AFPR, because the Holley I have keeps hitting the plenum.

I will let everyone know as soon as I figure it out tomorrow.

Thanks,
Craig
 

G Winter

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I believe you are right about the check valves but maybe one went bad? Would be about the simplest place to start. Remove the check valves and use pipe caps or plugs whichever happens to fit.


Glenn
:w
 

SPANISHVETTS

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It does sound like a vacuum leak.

How is the Idle speed?

The check valves on the air injection tubes are fairly rugged and I think that the noise that you would get from one of them failing would sound more like an exhaust leak than a squeal.

I would try to pinpoint the noise with a stethoscope or some of that spray that is basically propane. (do not know the name because we do not have it here in Euro-land)* when the spray is pulled into the motor by the vacuum the RPMs will soar for a second.

*Bro Junk must have a can or two of it laying around.
 

gmjunkie

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It does sound like a vacuum leak.



I would try to pinpoint the noise with a stethoscope or some of that spray that is basically propane. (do not know the name because we do not have it here in Euro-land)* when the spray is pulled into the motor by the vacuum the RPMs will soar for a second.

*Bro Junk must have a can or two of it laying around.

Actually I use a spray bottle of water with a stream,when it sucks water in it starts Popping and Farting Like a Old Johnny Popper John Deer!!!! I'm used to the sound of them!!:chuckle :chuckle I don't use Shine anymore,you can't see that stuff burning in the daylight!!!
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vetteboy86

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If it were a vacuum leak I would think the noise would start when I start the car. However it doens't start until the coolant temp is 178 or so. Then like a switch this noise occurs. I used some carb cleaner and sprayed around things but no luck. The car seems to run fine with or with out this problem.

I removed the air pump. Is there anything on these cars that would create a tone of sorts knowing that the solenoids were removed that go with the air pump?
 

G Winter

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Hummmm 178 deg..... when do your cooling fans kick in?


Glenn
:w
 

94conv.

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shouldnt there have been a block off plate that came with the pulley that blocked off where the pipe went into the manifold?
 

SPANISHVETTS

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If it were a vacuum leak I would think the noise would start when I start the car. However it doens't start until the coolant temp is 178 or so. Then like a switch this noise occurs. I used some carb cleaner and sprayed around things but no luck. The car seems to run fine with or with out this problem.

I removed the air pump. Is there anything on these cars that would create a tone of sorts knowing that the solenoids were removed that go with the air pump?
This brings back bad flashbacks of my problems with Thunder. A bead of the right stuff on the baseplate was breaking down when it got hot and letting coolant enter the intake. We chased the problem around the world until enough of the sealant broke down to cause an ongoing problem.
 

gmjunkie

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This brings back bad flashbacks of my problems with Thunder. A bead of the right stuff on the baseplate was breaking down when it got hot and letting coolant enter the intake. We chased the problem around the world until enough of the sealant broke down to cause an ongoing problem.
That would account for the whistling sound,and why it don't stop for a while after it's shut off!!:upthumbs
 
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vetteboy86

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There are no block off plates provided with the pulley. There is a little air moving, but not the problem I was facing.

The coolant fans come on around 175, but I eliminated this problem because the fan came on once and cooled the car down, and the second time the fan was running this problem happened.

I do believe I have it figured out. There were two things that concerned me. 1. The fitting for the brake booster had dried and cracked pipe dope, which I cleaned and replaced with thread tape.
2. There were two loose runner to intake bolts loose :bash. (The side that my bro was doing :)) I also had installed a bolt which I thought drew up, but come to find out it was too short and never grabbing any threads.

So after all this, I started the car and let her ran with absolutely no problem. I have not driven the car yet, but we will hopefully see and I should have no more problems.

I hate to consider it to be something else since this just did start after the mods. Had this noise been prevelant before I might have chased a whole different set of things.

Thanks for all the suggestions,
Craig
 
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...2. There were two loose runner to intake bolts loose :bash. (The side that my bro was doing :))....

Hey now when I put those in all I heard was "DONT TORQUE THEM DOWN YET!!!" and I saved your arse from having to take the valve covers off to put the runners back on.
 
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vetteboy86

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Drove the car for a while tonight with no problems. The vacuum leak is apperently gone. It must have been where the aluminum was getting heat soaked and that is what created the leak. No leak however with all necessary bolts torqued.
 

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