Boost leak... Through return line?!?

[LiquidGS-T]

Car was seeming sluggish, i did a boost leak test on my T04B V-Trim, and when it got up to about 7psi you could hear bubbling inside the block. Automatically i thought the worst and we started doing compression checks and everything else, but nothing seemed wrong. 160 across the cylinders, coolant and oil had no mixture or contact with eachother.
We drain the oil, do a boost leak test, bubbling stops. Now mind you it was bubbling like somebody was blowing through a straw into a glass of water. I pull off the return line, and test again. With my thumb over the return line whole, i can feel the air blowing out, but it was such a small amount, practically nothing at all. I put the return line into a cup of water to make sure. Thats definitely what was causing the bubbles.
I also found a pretty bad boost leak from my throttle body from where the cable connects. and a vacuum hose that runs to the boost controller had a slit in it. Vacuum hose was fixed, and i have another throttle body, not on yet.
Put the car all back together and called bullzeye. The guy was confused, hasn't heard this one yet. But he said that there is some air going to get through the seals like that. I've never run into this before, so i'm still a little shook about it. He said to send it in anyway to get checked out.
I take the car for a drive the next day. Its more powerful then it's been since i bought the turbo, the car runs awesome. I actually couldn't believe the way it felt. Its got way more power than its ever had with my 16g, and it still has the throttle body leak.
I guess my question is. Has anybody else ever noticed or run into a very small amount of air coming out of the oil return line? AND, do you think this could cause any kind of damage to anything?

sorry its so loooonnggg

 

[chicagoboostin]

subscribed.. this is an interesting problem.. if it is a problem.. i would also like to know whats going on..

 

[Raph]

subcribed..keep us posted

 

[sleestack]

Completley normal.

Turbochargers do not have seals made of rubber. The device used in most (some have carbon seals) turbos to make a seal are called piston rings. Just like the rings around the pistons in your motor these rings have a small end cap. This seal is reffered to as dynamic becuase unless the turbocharger is spinning there is a very poor seal being made. This gap will allow compressed air to pass and travel down the return tube to bubble in the pan. There is one compressor side ring and one turbine side ring.

In fact, oil can acutally bypass these seals if the bearing housing is allowed to fill with oil or there is excessive crankcase pressure. A greal deal of oil can pass these rings without actually damaging them. When the condition that causes the bearing housing to fill with oil is corrected the rings are usually ok. Usually a seal is only damaged if the bore they sit in is damaged or there is excessive thrust play in the turbo that allows the seal to pop out of it's bore.

 

[99gst_racer]

^^^ What he said. ^^^

It is completely normal; it happens to me everytime I boost leak test from the compressor housing....

If it bothers you, you can pull your LICP off of your compressor outlet and connect the boost leak tester to the pipe. Basically, just bypass the turbo.....

 

[LiquidGS-T]

Thanx for the info.

It mainly has me worried because my 16g never did that. If you guys are sayin its cool then i'm really REALLY relieved. But now i gotta figure out why the car seems sluggish.

I'm gonna fix my throttle body, and get it on a dyno and tune it.

Thanx a lot guys, major help and relief