Boost Leak testing question

Onefast99gsx · 08-21-2005

Hi Guys- I want to do a thorough leak test. I'm gonna do it from the intake of the turbo like the vfaq. I don't understand it though. Won't the air that i'm pumping in just leak out the exhaust valves? I've read some posts that say to set #1 at TDC but i don't see what good that does because setting it at TDC doesn't close all the valves. Some are open some are closed. Can someone please explain to me how to boost leak test the entire system. I could block the 2.5" pipe before the t.b. elbow but i want to test the whole system. The vfaq doesn't explain this.

Thanks.

**JET** · 08-21-2005

Don't worry it works. When it is at TDC you won't have both the intake and exhaust valves open. If the intakes are closed, then air doesn't get in the cylinder. If the exhaust is closed, it doesn't get out.

Onefast99gsx · 08-21-2005

Thanks Jet. I see what you mean. There are always valves open but never would the intake & exhaust valves be open at the same time, same cylinder. I didn't think of that.

Thanks.

Onefast99gsx · 08-21-2005

Hi Guys- Well i build a nice leak tester with a steel type valve stem. However... what the heck am i doing wrong. I set #1 at TDC(marks lined up, no problem). Took my intake pipe off the turbo inlet and put my leak tester on. Air hose thing bad but i was able to get 'some' air in but couldn't build any pressure. I could hear some liquid bubbling noise. Wasn't coolant. It sounds like it's bubbling in the pan. What's up with that. Why do i hear oil bubbling?

Thanks for any help/suggestions.

**Shane@DBPerformance** · 08-21-2005

Blown turbo seal? Maybe that is the cause of your knock also.

Onefast99gsx · 08-21-2005

Thanks Shane. I knew either you or Jet would reply first. Shit! Brand new PTE 50 Trim too. Well probably less than 4000 single owner miles on it.

The shaft does move probably a couple of millameters side to side. I think more than it did when i first got it. I've changed oil twice within less than 4k miles. Always Mobil 1 synthetic.

I guess my next 3 questions to you would be---

1) What would cause this? The highest i've boosted is 24.5psi

2) Are these fairly easy to change?

3) Approximately how much $$ to replace these on a PTE turbo.

Thanks Shane. Man i hope this is the source of my Knock problems.

**Shane@DBPerformance** · 08-21-2005

Test off the front of the turbo again and try to gauge how much air is coming out the breather hole. Then try moving the tester to your throttle body elbow and see if you can still hear the bubbling and if the amount of air coming out the breather hole has dropped significantly. If its still bubbling or the airflow out the breather has dropped to almost nothing, then it is something else. Do you have an air compressor or something that can move a fair amount of air? The turbo should have a 1 year warranty on it.

Onefast99gsx · 08-21-2005

I'm gonna pop the intake pipe back on and take it over to dads shop. The only compressor i have is just a little 2 gallon portable one. You pump air out of it and it kicks on right away so it's hard to hear air coming from anywhere. The bubbling just happens to be loud enough to hear. Lately it seems like the car has been using some oil i might add. When the head was rebuilt, all new valve seals were put on. I have no clue where the oil is going. It's not an external leak. If it's smoking i can't see it too well. I'm gonna have to add a compression test to my checklist too. I'm gonna have to get back to you on this one. I'm just trying to point my knock issue at anything now. I will do a better test tommorow night after work.

A long shot but, ... Can internal oil leaks caused by valve seals, compression leaks, etc.. cause knock issues?

Thanks.

Onefast99gsx · 08-22-2005

Ok guys. I did my extensive testing tonight with a much larger compressor. Filled compressor to about 35psi so i wouldn't overdo it with too much.

Test #1, same test as last night. Put boost leak tester on turbo inlet. Could hear
blub--blub--blub--blub--blub...etc...down in the oil pan. --- Was also hearing another leak too.

Test #2, put leak tester on t.b. elbow.
Result-- No more blub--blub in oil pan. Was hearing a pretty strong leak on the throttle body butterfly valve right were the recoil spring is. Leaking pretty good all the way around. Sounded like a leaky air hose fitting.

In both tests, air leaked out right away. Could not build up any pressure in either test. So i got 2 nice leaks. The turbo leak would probably account for the oil i smell. I don't really see smoke but i can smell the burning oil.

So... do i just need new oil seals for the center cartridge of the turbo or do you need all new bearings, etc... Turbo less than 4k miles old. Is this something that i can do myself or does it need re-balancing afterwards? I know there is probably a warranty but i'm afraid to send it to PTE for the sake that it will probably sit there forever.

As for the throttle body, is this generally a seal or o-ring that goes out and needs replancing?

Thanks much.

**Shane@DBPerformance** · 08-23-2005

Leaks at the TB shaft are common, but they usually aren't all that big. They aren't all that simple fix either, so most people live with them. Yours sounds like a big leak, unless its just your compressor is running out of air too quick. Do you have a regulator on the compressor? Usually you want to fill the compressor tank all the way up to it's highest pressure and then use a regulator to turn it down to 15psi or whatever on your boost gauge in the car and then pinpoint leaks. Then at least you might have some airflow for a couple minutes, unless your tank is tiny.

I wouldn't try to rebuild it myself, if it's still under warrenty. If you find more wrong with when you take it apart, then you will definately be screwed.

Onefast99gsx · 08-23-2005

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 · 08-23-2005

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.

-------------

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 · 08-23-2005

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 · 08-23-2005

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** · 08-23-2005

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 · 08-23-2005

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.