Best way to check for a boost leak?

[Kspen90]

I've been noticing a different sound from my turbo since I had my new injectors put in, it almost sounds like a belt driven supercharger whine when the turbo is boosting. My first guess is I have a boost leak somewhere because my turbo doesn't hold steady boost pressure when I keep the pedal in the same spot, it will fall down to 5psi or less. So I was thinking to check of a leak I would disconnect the hose coming out of the turbo and the one going into the y bridge the put a PVC pipe cap in one end and tighten the hose clamp down on it the get another cap and put a tire valve stem in it and put in in the other end and pressurize the plumbing and see if it holds pressure or not, or am i having a different problem thats causing this issue? Any and all opinions are greatly appreciated on this subject. Thanks

 

[turbostang7]

I made a tester for mine, took the intake off, found a rubber coupled that fit it and some pvc pipe put a cap on the pipe, then drilled and tapped one hole for a guage and then drilled another hole in the cap for a tire stem and aired it up to 35 psi then sprayed all conection for leaks.

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[Kspen90]

I made a tester for mine, took the intake off, found a rubber coupled that fit it and some pvc pipe put a cap on the pipe, then drilled and tapped one hole for a guage and then drilled another hole in the cap for a tire stem and aired it up to 35 psi then sprayed all conection for leaks.

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Were you experiencing the same sound that I described above?

 

[Devon]

Mine is currently making the supercharger whining noise due to air leaking between the intake mani and intake bridge horn, there's a metal gasket between there. The flange is cracked on my intake horn that's how I know. Only get about 6 psi of boost


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[Kspen90]

Mine is currently making the supercharger whining noise due to air leaking between the intake mani and intake bridge horn, there's a metal gasket between there. The flange is cracked on my intake horn that's how I know. Only get about 6 psi of boost


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Mine will surge to 22psi as long as I keep it floored but as soon as I level off to a constant rpm the boost falls to 3-5psi. Are you saying that the y bridge is two separate pieces or are you talking about the turbo intake horn?

 

[Kspen90]

Any other advice or suggestions anyone?

 

[McRat]

If you make a plug and test with compressed air, you can HEAR a leak. Use a stethoscope to locate if nec.

Boost leaks usually leave faint marks. Even if the air going into the motor is 100% clean, it still has water in it. When the air leaks, it comes out of solution, and leaves a mark.

 

[Kspen90]

How would i test the y bridge to see if that is what is leaking?

 

[Devon]

Well with mine you can clearly see the metal gasket vibrating between manifold and bridge horn.


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[Kspen90]

I will have to rip mine apart and look but I was thinking plug the exhaust and pressurize from the turbo outlet tube. What is everyone's opinion?

 

[Kspen90]

Anyone?

 

[turbostang7]

if you build the tester like i did it will presurize even the y bridge, everything that is under boost will see the pressure. i only did mine because it was wrecked and i put a whole new front end on. figured while everything was apart and easy to get to all sides of the boots was the best time!

 

[Kspen90]

Air didnt escape through the open valves?

 

[McRat]

In order for a large leak to go right out the exhaust valves in the engine, one cyl must be at overlap. Every two engine revs, 720deg, there will be 8x overlap. If overlap = 40deg, that's 320 deg. So about a 50/50 chance. Unless there is 90 deg overlap, there is a position with no overlap.

So where do you put the crank? If one cyl is TDC, you will have overlap on the opposite cyl. If one cyl is BDC, ditto. If one cyl is 90 or 270, ditto. So you get to TDC on any cyl, then rotate 45 deg. If there is a zero overlap region, this is it.

Or so my theory goes. Makes sense on paper.

 

[Bryce418]

I will have to rip mine apart and look but I was thinking plug the exhaust and pressurize from the turbo outlet tube. What is everyone's opinion?

Gm actually has a tool that clamps to the bottom of the downpipe and has a nipple to attach a regulated air supply. Then cap the intercooler pipe and run air in regulated at 30 psi, if it maintains more than 27 psi it passes.

 

[Kspen90]

Well I found the culprit, the clamp was loose on the hot side of the intercooler boot, but on the intake tube side and the way the clamp was turned it was a MAJOR pain in the ass to get to. It would hold fine until pressure hit 22psi then it would leak which explains why i could only get 22psi out of my truck lol Thanks for the input everybody

 

[Kspen90]

Gm actually has a tool that clamps to the bottom of the downpipe and has a nipple to attach a regulated air supply. Then cap the intercooler pipe and run air in regulated at 30 psi, if it maintains more than 27 psi it passes.

Do you know what they call this tool and how much it costs? Id like to have one for any future leak checks