Boost Leak Test. Bubbling Sound

[khiabpim]

I did a boost leak test on a 2g GST with BB turbo today. The reason I'm doing BLT is because I just recently got DSMLink and having hard time zero out LTFT, so I'm trying to eliminate boost leak. I hooked up the boost tester to the turbo inlet and pressurized it to 15psi and slowly decrease. I found two problems.

#1) I can hear a little hissing sound coming from the throttle body, but can't pin point where it's coming from, this I'll find and fix it.

#2) This worry me, I hear bubbling sound coming from the engine head when I took of the oil cap. I have read that the bubbling sound is cause by blown head gasket. Is this true? Other also said that bad turbo seal is what causing the bubbling sound, becuase air leak to the oil pan through the oil return line. Some said it's normal for air to pass through the seal during a static pressure test due to the lack of oil pressure as long as it's not leaking during operation. I'm confuse to what's causing the bubbling oil sound. Could someone please explain to me what's causing this.

There is no oil residue on the turbo or intercooler pipping and no smoke coming out from the exhaust. I haven't try to do the leak test after the turbo, because it's getting dark out. I'll try to do that tomorrow and see if I still hear the bubbling sound. Untill then could someone please explain this bubbling issue for me, so I could get a better understanding of what's going on, if possible fix it.

 

[Artago]

#1 Suspect TB shaft seals
#2 Suspect PCV

Tom

 

[khiabpim]

Well. I did another boost leak test this morning. This time I connect the tester to a section of the intercooler pipe after the turbo. The hissing sound from the throttle body still there, and found out air is leaking through the Bliss, does this mean I need to get another screw or can I change the O ring and where can I find the O ring?

The bubbling from the oil cap is gone, but now I hear a little hissing sound. What could this be? Is this happen due to PCV or something more major? Sorry I'm new to DSM, but where is the PCV located.

 

[Auto RS T]

Fill out your vehicle profile so we know what we are working with.

Try replacing the o-ring first to eliminate your BISS leak.

By going to the intercooler piping with the BLTester you eliminated the turbo oil return line. This sounds like it was your bubbling.

The hissing is most likely the PCV, it is threaded into the backside of the valve cover. A hose runs from it to the intake manifold. To test it, unthread it from the valve cover then hook the hose back up to it and do the Boost Leak Test. It shouldn't leak, but the majority of them do slightly.

Heres a read.

http://www.dsmtuners.com/forums/newbie-forum/229338-stupid-pcv-question.html

 

[khiabpim]

Well. I fixed the leak on the bliss by buying an O-ring from Home Depot and also fix some minor leaks as well. I did not take the PCV off but disconnect the hose and plug it off. I could still hear little hissing sound coming from the oil cap, so it's not the PCV. I think it's something else. Any idea what could that be, the engine knocks a little when start up, but goes away when engine is warm. No smoke.

Mod.

Stock 2g Head/Block|Port EVO 3 Exhaust Manifold| Port 2g o2 Housing|L2R BB Tubro|Denso 660cc|Supra Fuel Pump|Greddy 850 FMC|Apex 3" N1 Catback|Apex 2.5 Downpipe|Blitz BlowOff Valve|HKS Turbo Timer|Autometer EGT/Boost Gauge|Aeromotive Fuel Regulator w/ B&M Gauge|AEM UEGO o2 WB|

 

[Auto RS T]

Valve seals or piston rings.