Engine/Transmission (1998.5 - 2002) Strange boost whistle

[GMincher]

Just looking for ideas. And it has been my experience that this IS the place!! I've got an unusual high pitched squeal under heavy load that is boost

related. I've checked all the boots, eveything looks fine... is it unusual for an intake gasket to blow? If I had to guess, a small flat opening would make this kind of whistle and the intake is the only thing that comes to mind.

Now, how 'bout trouble shooting this one? I'm trying to think of ways to pressurize the intake system and then add soapy water. Your thoughts and comments as usual would be appreciated! Thanks, Greg

 

[DMcPherson]

looking at the boots usually doesent make any thing obvious. if o have the means to pressure check than do so. its pretty easy. anything solid that will fit into an intercooler hose will work, plug one and drill one and ionstall a schrader valve. I hve one similar with an extra fitting and a boost guage attatched. that is the most common. wither that or I have seen intercoolers with holes quite commonly also.

 

[johncameron]

When changing my injectors I broke the intake air horn gasget below the grid heaters. I then had a horrible squeel until the new gasget came in! It doesn't take much to make an awful racket under pressure.



John

 

[nps]

I made a round plug out of 1/4" particle board (easy to cut and file into shape) to replace the air filter. Into the center of this plug I drilled a hole and installed an old tire valve stem.



Take out the air filter, install the plug and tighten the clamp. Put an air hose on it and listen for the leaks. Just make sure the air pressure you feed is less than 45-50 pounds or you could blow out a gasket or seal inadvertently.

 

[GMincher]

Well guys, I built a nifty PVC plug/pressure tester and it told me that the intake gasket is sure enough blow out. The front bolt under the accelerator linkage had loosened... alot.

This was that weird leakdown sound every time I turned off the engine!!! It's been doing this for over 2 years! The gasket section finally blew out and that created the new squeal.

Now it looks like a not so fun job to replace the $8 gasket. The truck has always run well, I can't wait to see how much better it runs after this is fixed. Thanks for your help, Greg