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GM 1.4L Turbo Boost & Coolant Leak Testing Kits

60K views 34 replies 10 participants last post by  ppvsteve  
There are a few noises that occur besides the high pitched one. I am getting ready to replace the idler and belt to hopefully quiet the AC when it's running and am also replacing the crank seal to silence the chirp. Is there anything in the vicinity of the throttle body spacer, besides the spacer itself, that might be the source of the leak?

I have already replaced the valve cover and the PCV orange nipple is still there.
 
Just because the nipple is there doesn't mean it doesn't leak, or that it's not cracked behind.



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So do you have an idea where the leak may be coming from - reference the video.
 
Can't tell from the video but it's a huge leak. Start spraying everything in the engine bay with soapy water and see where it starts bubbling.

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It occurs when I hit 13-17 psi, but only with constant pressure. When I drive it only happens on occasion and I can tell because the engine bogs a bit.

On my second try, I did spray soapy water and no bubbles. It does get louder as get closer to the bottom of the throttle body spacer though as seen at about 2:20-2:30
 
I have since then, but have corrected them so far. I do not think they are related as the leak is not something that occurs at normal boost levels.

The 171 was from when I checked on the orange nipple and accidentally pulled the clip out too far and subsequently lost the plastic ring when it and the o-ring fell out.

I've cleaned the MAF &, Turbo Boost sensors as well cleaning and re-oiling my air cleaner and that has cleared the other two.

P0420, p0171, P0?? I forgot the last one, but it was like P0129 if I remember correctly.
 
Unfortunately, not all of us are in a position to have a compressor. Is this something that could work with a small tire pump? Perhaps one of those small ones powered from the cigarette lighter?
I know this is older than dirt, but it just occurred to me that you could possibly use a portable air tank with the hose modified to attach to the leak tester. I bought mine from Menards for $20 or so.

This is one from HF: 5 gallon Portable Air Tank

With this coupon good for the Holiday it will be only $23.99

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Or if you can't make it this weekend, this one is good to the end of the year:


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Have you ever published any guidelines as to what level of decay will start producing Lean codes?
I am at:
20 PSI to 15 PSI - 21 seconds
20 PSI to 10 PSI - 60 seconds
And am getting P0171 code only

Is running pretty good, smooth for the most part.

Cruzekit 3.4 installed 30K mile ago - put fresh PCV valve in the hose.
New Intercooler to Throttle body intake hose assembly ( previous one oil saturated and rip developed )
New turbo Assembly installed- Felpro Head gasket.
Purge valve seems fine. But by eliminated it anyway and plugged purge line just to see if any improvement, still got P0171
Soapy watered everything I could up top, not seeing or hearing any leaks. But my hearing is not great these days.
My last step is getting under the car and spraying up at the bottom of the intake manifold if I can even see it!

Is there a certain magical decay time if I hit it I can stop looking for boost leaks and maybe consider faulty O2 sensors or MAF sensors?

Video of Pressure decay.

Probably not what you're looking for, but this is what I have:

Boost Leak links as of 06AUG2025