huge Vacuum leak, no idea where its coming from

[LucidEclipse]

Hello, my 97 gst is nothing but a headache. I have gone through and replaced all hoses, throttle body, intake mani gasket and I am still getting a huge vac leak somewhere around the intake manifold. I sprayed the intake mani down with some carb kleen this morning only to find nothing. You can surely hear a leak but I can't figure out where it is. Is there any part thats prone to leaks? the car has 160k miles so the parts are pretty worn. I did a compression test on the motor, perfect 180 on all cylinders. Another problem I found is that there was quite a bit of oil residue in the intake manifold and a LOT on the throttle body flap. The car ran with a siezed 16g on it for about a month so i figured that was caused by the turbo. I took off the intercooler piping only to find not a drop of oil which i found as VERY unusual. Any help is greatly appreciated as I am fed up with it and will probably just take it to a mechanic at this point.

 

[Supa Dexta]

Injector seals?

 

[Maxboost1010]

Wait, before you take it to a mechanic, just know the TB is prone to leaks at the TB shaft seals, and the way you test for it is by doing a boost leak test. During the test while at about 15psi open and close your TB if the noise changes, then you DO have bad TB shaft seals. I just replaced mine like 2 days ago, its not too bad if you are somewhat mechanically inclined, but if you are not then it can be a pain and remember you will have to set the TPS Sensor back to .9K ohms after you are done replacing the seals. I took a pretty good picture of where the leak that you can refer to in one of my posts that I have not been able to solve yet, look at http://www.dsmtuners.com/forums/pro...rges-falls-its-face-around-4000-5000-rpm.html look at post number 14 pic 1. Again this whole thing is based on the idea that you probably hear the noise while you are driving (probably from the passenger side) and can't when you are at idle since you said you couldn't see any bubbles. Hope that helps let us know what it turned out to be. Also look at and consider your Injector seals, and maybe do an leak down test. One more thing to consider is the condition of your PCV valve and PCV system for the oil problem.

 

[Ceddy]

If you have a EGR block-off plate check there. I had a huge leak there that I couldn't figure out where it was coming from.

 

[LucidEclipse]

thanks for the advise, Im going to run another boost leak test at this point. I dont have an egr blockoff plate infact I dont even know where that would go.

 

[LucidEclipse]

ran it up to 15 psi with no signs of leakage, turn the caron and same problem, hesitation, erratic idle, wont go above 3k rpm,s all kinds of blue smoke, dont know where to go from here I guess Ill just let a mechanic fix it. BTW the compression on the motor is excellent, 180 on all cylinders so I doubt its the motor.