2G Boost Leak Test Questions

[Mham2k]

I have been fixing boost leaks over the last few weeks and now i'm stuck.

1.) I went from holding 5psi to now holding 12psi
2.) I rebuilt my throttle body, new gaskets on BOV, new gasket on valve cover, tightened many couplers, ect.

Now I hear no air and see no soapy bubbles but my car will only get up to 12psi on the test.

How can i find the other leaks?

 

[Kryndon]

Is that on the stock T25 turbo or other? For T12, 12-13 psi is perfectly healthy.

If you're on a different turbo, maybe check your vacuum lines that link the BCS, Wastegate Actuator and Compressor housing. If those aren't linked correctly or not at all, you will be running boost off the wastegate, which would depend based on your turbo. A T25 gets about 7 psi based just on the wastegate.

 

[Mham2k]

Is that on the stock T25 turbo or other? For T12, 12-13 psi is perfectly healthy.

If you're on a different turbo, maybe check your vacuum lines that link the BCS, Wastegate Actuator and Compressor housing. If those aren't linked correctly or not at all, you will be running boost off the wastegate, which would depend based on your turbo. A T25 gets about 7 psi based just on the wastegate.

Running a TD06 20g
I can run it at 20psi but i can't get the boost leak test to hold 20psi.

I can't find anymore leaks anywhere, I think I need a smoke tester...

 

[Dsm panda]

Try hooking the tester up after the turbo. My e316g had some shaft play and was allowing pressure into my oil system if you hook up after you can eliminate the turbo as the issue.

 

[Mham2k]

Try hooking the tester up after the turbo. My e316g had some shaft play and was allowing pressure into my oil system if you hook up after you can eliminate the turbo as the issue.

Ok will try that.

 

[miguelmcv]

If you want to make sure everything seals up really good, do it in sections, do one at the throttle body inlet, do another before the intercooler and lastly at the Turbo inlet, this way you will be eliminating leaks easier.

 

[Vegas Smith]

A lot of turbos will leak air through the j-pipe into the engine; especially old ones with worn out seals. Take off your catchcan line that goes to the side of the VC and see if air is coming out of there.

 

[Mham2k]

If you want to make sure everything seals up really good, do it in sections, do one at the throttle body inlet, do another before the intercooler and lastly at the Turbo inlet, this way you will be eliminating leaks easier.

Great idea! Will try that after I check to see if my turbo seals are leaking.

 

[Mham2k]

A lot of turbos will leak air through the j-pipe into the engine; especially old ones with worn out seals. Take off your catchcan line that goes to the side of the VC and see if air is coming out of there.

VC? I will check this to see. If my turbo is leaking I will need to get it rebuild correct?

 

[Mham2k]

Just so everyone knows the leaks I have fixed
1.) Thottle body rebuilt (shaft seals, gaskets, biss)
2.) IC Couplers Tightened
3.) Turbo to manifold gasket replaced
4.) O2 Sensor housing gasket
5.) A few hose clamps replaced
6.) BOV gasket replaced

All this stuff took me from 5psi to 12psi boost leak test pressure...

I can't hear, feel, see, or soap bubble any other leaks. Nothing is leaking out of the system that I can tell but it is still only holding 12psi

 

[Vegas Smith]

VC= valve cover

If air is getting past the turbo on a BLT it doesn't exactly mean that it's bad. Those seals probably aren't meant to be airtight. When the car is running you'll most likely not have any leakage. It's more of a dynamic seal if I recall. You should be able to get much higher on a BLT than 12 psi.

 

[Dsm panda]

Check your injector seals mine where leaking really bad but I only found out when I got it to 20psi with a big compressor and it would drop to like 10psi and stop leaking. Just a thought.

 

[miguelmcv]

Where are you loosing pressure?
If you did a test at the throttle body you will know if its holding over 12psi, same thing before the intercooler test, if all is holding good and you are loosing pressure before the Turbo then you know is the Turbo, so you are good.
Turbo leak during the test is normal after it runs it seals it self..

 

[Mham2k]

VC= valve cover

If air is getting past the turbo on a BLT it doesn't exactly mean that it's bad. Those seals probably aren't meant to be airtight. When the car is running you'll most likely not have any leakage. It's more of a dynamic seal if I recall. You should be able to get much higher on a BLT than 12 psi.

A friend of mine just asked me if i plugged the hole that goes from the turbo to the boost controller. I don't think i did, I will try that. It might be traveling up from the turbo, through the selenoid, and dumping out of the wastegate into the exhaust.

 

[Mham2k]

Where are you loosing pressure?
If you did a test at the throttle body you will know if its holding over 12psi, same thing before the intercooler test, if all is holding good and you are loosing pressure before the Turbo then you know is the Turbo, so you are good.
Turbo leak during the test is normal after it runs it seals it self..

Ok thanks

 

[Mham2k]

Check your injector seals mine where leaking really bad but I only found out when I got it to 20psi with a big compressor and it would drop to like 10psi and stop leaking. Just a thought.

Injectors and seals are new, soapy water doesn't bubble.