Boost leak test = leaking to exhaust

[blackbyrd]

Hey everyone,

So I picked up a 1g TSI and was *told* the engine was in good condition, not running cause of some electrical problems. I was doing a basic boost leak test hooked up at the UICP, and all the air was rushing out through the exhaust pipes. (Yes, I was at 30*ATDC). I tried bumping the crank a little more, cm by cm, trying and testing it. Went all the way around twice and I couldn't hit a single spot where it wouldn't leak out the exhaust, all about at the same rate.
I checked the timing and it appears to be spot on, didn't hear any metal clanking when rotating the crank.
Any ideas, Preferably positive? or Is my head dead?(ha ha)

Thanks!

 

[97gsx_zeclipse]

Was your car fully warmed up? I had this problem before and did the boost leak test in the morning because I didn't want to hook up the boost leak tester to the turbo when its hot. If its not warmed up it will leak past the seals. Have you checked your pcv valve?

 

[cruisintalonawd]

Was your car fully warmed up? I had this problem before and did the boost leak test in the morning because I didn't want to hook up the boost leak tester to the turbo when its hot. If its not warmed up it will leak past the seals. Have you checked your pcv valve?

he putting it to the Upper Intercooler pipe not the turbo any ### so he's pretty much doing it wrong.

Put the crack on TDC and checker your cam gears, you might have bent exhaust vavles

 

[romeen]

Was your car fully warmed up? I had this problem before and did the boost leak test in the morning because I didn't want to hook up the boost leak tester to the turbo when its hot. If its not warmed up it will leak past the seals. Have you checked your pcv valve?

Performing a boost leak test on a cold motor will allow air to get past the piston rings. But this will put air into the crankcase, not the exhaust. Same thing with a leaking PCV valve.

Hey everyone,

So I picked up a 1g TSI and was *told* the engine was in good condition, not running cause of some electrical problems. I was doing a basic boost leak test hooked up at the UICP, and all the air was rushing out through the exhaust pipes. (Yes, I was at 30*ATDC). I tried bumping the crank a little more, cm by cm, trying and testing it. Went all the way around twice and I couldn't hit a single spot where it wouldn't leak out the exhaust, all about at the same rate.
I checked the timing and it appears to be spot on, didn't hear any metal clanking when rotating the crank.
Any ideas, Preferably positive? or Is my head dead?(ha ha)

Thanks!

You may be leaking air past the EGR valve. There is an opening in the #4 exhaust port which is where the EGR samples the exhaust gas from (it's suppose to only go one way, from exhaust port--->intake manifold). If you have a faulty EGR valve then it may be leaking into the exhaust. Here is a thread which discusses this along with a picture of the EGR opening in the exhaust port.

http://www.dsmtuners.com/forums/tuning-engine-management/215694-boost-leak-test-question.html

BTW, I might have the same problem. I will be doing a leak test later today or tommorow and I am going to use a mechanic's stethoscope to listen at the EGR valve to see if I can hear air passing through it (I don't feel like removing my turbo/manifold at this point). I will let you know how it works.

Also, you may want to do a compression test to rule out any issues with the valves/head.

 

[blackbyrd]

Thanks guys!
The car was not warmed up, it's not running yet, but i've pressure tested cold engines before without these results.
How am I doing it wrong by testing at the UICP/TB? TDC would have valve-overlap definitely producing this result, thus why 30* ATDC is recommended.
It's not leaking into the crank, and its not leaking through the PCV valve.
EGR is a good point, I have not checked it, will check it out tonight.

 

[95blackGsTurbo]

Your best bet is to fix the electrical problem and get the car warmed up and do a leak down test. That will let you know what's leaking and how much.

 

[kenamond]

Thanks guys!
The car was not warmed up, it's not running yet, but i've pressure tested cold engines before without these results.
How am I doing it wrong by testing at the UICP/TB? TDC would have valve-overlap definitely producing this result, thus why 30* ATDC is recommended.
EGR is a good point, I have not checked it, will check it out tonight.

cruisintalonawd is full of it. You can boost leak test on the UICP, TB elbow, LICP, or compressor inlet.

I agree with 95blackGsTurbo that you should get the car working before doing the boost leak test. Until you get it running, I don't see an easy way to test compression, boost leak test, etc.

 

[cruisintalonawd]

well if your gonna do a boost leak test, why skip the turbo and intercooler

 

[turbosax2]

well if your gonna do a boost leak test, why skip the turbo and intercooler

If you boost leak test at the throttle body elbow first, it's easier to pinpoint leaks from there on because you have a smaller area to focus on. This doesn't mean you neglect the rest of the system, but you break it into smaller parts. Same thing goes for testing at the uicp and licp.