Boost Leak testing question

[Onefast99gsx]

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]

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]

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]

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]

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

[Onefast99gsx]

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]

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]

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]

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]

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.