Thread: Locating a vacum leak.

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I have removed the stock exhaust on my 89 suburban TBI. I added long tube headers and installed a y pipe back in to the system. High performance cat with a flowmaster muffler in the system. From the back of the headers its 2.5 tubes going in to the y and goes 2 into 1 with a 3" pipe for cat and muffler. After muffler it splits back up to 2 2.5 pipes out the back.

Problem now is that it runs better but when I push the gas and let of quickly I have a small whistle coming from the engine compartment. It only does it when I let off the gas quickly. I just got a vacum gauge going to see what I kind find out. I "think" it may be coming from the front or rear seal on the intake. Any ideas?

The front or rear seal on the intake are not exposed to vacuum. Did you take the intake off for any reason? Just trying to figure why installing headers would cause a leak at the intake.

Originally Posted by R Pope

The front or rear seal on the intake are not exposed to vacuum. Did you take the intake off for any reason? Just trying to figure why installing headers would cause a leak at the intake.

Its a after market intake but I did not remove it for anything. I have also retighened all bolts on the headers. There is some bad weather passing through so I cant really check it out to tomorrow.

Truck Driver ck. the gasket under the TBI they will go out due to age. we used to replace all the time when I worked at eldorado chev.

I found my leak. Its coming from the hooker headers where the four tubes go into the collector. Guess Ill get with summit and redo the install. Gas mileage does not seem so bad but the air leak is about 6-7" in front of the 02 sensor.

Talked to Summit and it took all but 5 minutes and we have another set coming in. I also purchased these about 4 months ago. Just did not have the chance to install untill last week. Its a hassle to replace them but I could of been stuck with them.

Well that sucks but glad you found the problem. Kurt