Boost leak test ???

[yankiwi]

OK...

My NA-T runs like I have a small boost leak. I recognize the symptom as I originally had a huge boost leak on the coupling immediatly off the turbo, that is now fixed. The rest of my induction system is brand new silicone/aluminum hardpipes. Yet the symptom still exists once the car is up to operating temps........

Here's what I did....

Removed AFM, plugged hole with same size plastic bottle and clamped down.
Removed vacuum line to brake booster, stuffed compressor attachment in there and "inflated" the system to 6psi.

Here's what happens....

I don't hold pressure, it slowly leaks down from 6 psi to 0 in about 12-14 seconds. Now, my logic says this should occur, as the air will pass through the valves and out the exhaust depending on where the engine is in its cycle...Correct? Or should this test be tight as a nun's nasty and hold pressure?

I cannot discern where the faint air hissing noise is coming from, but it sounds like it is leaving around the exhaust?????


Cliffs:

When a boost check is done correctly, how long should the pressure remain in the induction system before "leaking " down??????????

Thanks guys.

 

[staticpat]

If your filling it to the brake booster make sure the throttle plate is open or your only pressurizing the manifold. You want to pressurize the whole system. If you hear only faint hissing inflate it more than 6psi and try to hone in on it. I don't know how much valve overlap we have but losing all pressure in 14 seconds sounds reasonable.

 

[yankiwi]

Thanks staticpat,

I do open the throttle plate.

Anybody else done a test lately, that can give me an idea of how long it takes to leak down?

 

[MmmBoost]

any time ive done a leak test, i have pressurized the intercooler piping (from the turbo outlet to the throttle body) because thats usually the place that we are talking about a boost leak occuring. the 2 times ive had a leak, i set the compressor to 20psi and it was very obvious where the leak was coming from.