Boost Leak testing question

[Onefast99gsx]

I'll get a hold of Chris at Mitsubishi to order some new t.b. seals. Mine is a pretty good leak. We used a stethiscope to pin point it but the leak was plenty noticable by ear.... I was at dads shop. They have like a 180psi compressor and i just ran the compressor till it built up to about 35psi. It's a 120-150 gallon tank so it shouldn't have been running out. I held the fill hose on the nipple for 10 seconds and all the air just pissed out of the butterfly valve leak.

As for the turbo, I just called Brian at Precision Turbo this morning. He said yeah, it's under warranty and that they should be able to get it out the door in a decent time. That was my only worry. So i'll remove it tonight and ship it tommorow.

Question: What causes blown turbo oil seals in the first place? This turbo has less than 4000 miles, return line is 10AN braided, feedline 4AN braided, synthetic oil and ALWAYS turbo timed. Was never considered over-boosted either, 23# max. So i have done everything right to my knowledge.

Thank you.

[Onefast99gsx]

Shane- Found this stuff on dsmlinks website: Some don't consider it a problem However, I still smell burning oil out the tailpipe. My problem is seems to be a true oil seal issue.


I had this same question about a month back and this is the reply I got from FP

"Nothin unusual about the pressure going form the compressor housing into the crankcase. The seal is supposed to hold back a oil mist from leaving the bearing housing under normal operating conditions, if air is going from the compressor housing into the bearing housing then oil isn’t going to be coming out of the bearing housing.



This concern by itself doesn’t warrant rebuilding the turbo.



Regards

Robert Young
"

The issue from my research is that when the car is running the oil pressure on the seal is higher than the air pressure seen on the turbo side so air won't get past it. When you do a boost leak check the pressure is high and there is no oil pressure on the seal so the air goes past it into the crankcase.


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Turbo seals look like piston rings. They aren't designed to seal against air pressure without oil pressure behind them.

Dave

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[Alpine TSi]

I remember hearing something about PTE turbos and oil seals going or letting oil past when there was too much pressure from the oil feed. What size line do you have feeding it and where is it fed from? I remember people saying they used a restrictor in the feed line to help this problem.

[Onefast99gsx]

4AN feed from the oil filter housing
10AN return to the pan

I didn't use a restrictor because the little sheet of paper that came with the turbo said not to use a restrictor. It was very specific. I'm really confused and frustrated. I feel like i did everything by the book and this is what i end up with. I've read numerous posts on 3an vs. 4an for the feed and earlier in the spring i just decided to call PTE and they said go with 4an. Yeah i can send it out and have it rebuilt under warranty but what does that do me for the future?

[Shane@DBPerformance]

Are you balance shafts removed?

When I heard excessive bubbling and airflow out my breather hose compared to other times I tested, I sent my turbo in and the seals were blown and the backplate was damaged. I talked to PTE for a bit before hand to make sure it just wasn't because there wasn't oil pressure in the turbo while I was doing the test.

[Onefast99gsx]

No, the balance shafts are in just like stock. As a matter of fact it's the normal stock 2g 2.0l other than having 272 cams. I should point out that i did put all new valves seals on when the head was apart over the winter. Last night I did a pressure test when entire engine was cold and when it was warm. Both times i heard bubbling. When i called PTE this morning, the guy i talked to must have been more sales or something, he wasn't too technical oriented. It would be nice if people actually knew something about the products they were selling.

Also i want to add that the oil after only less that 500 miles on the oil change, seems to be darker than what i think it should be. Exhaust vapors must be getting to the oil?

I ordered the t.b. seals. Napa can get them but it takes 3 days to get them.

Being that i can smell an oil burn all the time and that the oil seems to travel down on the dipstick, i'm gonna have to assume that mine are blown as well. I hope after all this crap is said and done, that it helps my knock problems!

Thanks.