Boost Leak Test Results

[amaank]

Hi,

We did a boost leak test in out 92 tsi. The car holds absolutely no boost whatsoever. There is tiny leak at the tb and a small leak from a vacuum pipe. Otherwise the whole intake tract is fine. The intake mani, injectors, piping, ic.. everything seems good. With this, the car should atleast hold like 3-4 pounds for boost for a couple of seconds right?!

When the thermostat is filled to the brim during a test the coolant starts to bubble. I can hear other bubbling somewhere in the engine... like coolant in the head. From some searches i've done people say it is the air from the oil return line bubbling in the oil pan... i'm not too sure about this. I will check it out tomorrow with a stethoscope. I will do a compression test very soon. I don't have the materials to do a leakdown just yet.

The tests were done with a pvc end cap, valve stem style tester hooked up to the cold side of the turbo with a pretty hefty, powerful compressor. We also used soapy water to find the smaller leak.

Also when the compressor is hooked up and pumping air at full power the boost gauge goes up to 6psi and then drops to zero almost immediatly as the filler is removed from the valve stem.

Any suggestions would help! Thanks!

 

[amaank]

Yes, i will make another boost leak test tool to hook up to the intake manifold aswell.

 

[kenamond]

If you're seeing bubbling in your coolant, you've got a blown head gasket. I'd go and do the compression and leakdown tests first to confirm this and go from there.

 

[amaank]

uh oh,

The reason i didn't suspect it being a blow hg was because it runs well on stock chip and injectors. There is not a trace of coolant in the oil. The car doesn't blow any kind of smoke and actually pulls really well when it finally gets into boost.

I'll definetly do the compression test immediatly and try to get the tools for a leakdown.

 

[90gst_sean]

Check your turbo impeller. Make sure that it moves. I had a 14b go bad on me, the shaft had frozen. I would drive with the throttle wide open but I could not get any boost. I had vacuum but the gauge would not move past zero. I replaced the 14b with a Slow Boy Racing Evo3 big 16G and I have boost again.

 

[amaank]

Check your turbo impeller. Make sure that it moves. I had a 14b go bad on me, the shaft had frozen. I would drive with the throttle wide open but I could not get any boost. I had vacuum but the gauge would not move past zero. I replaced the 14b with a Slow Boy Racing Evo3 big 16G and I have boost again.

I will check that, thanks!