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Did a leak test, sounds like my turbo is leaking ??!!!

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bgilly

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Discussion starter · #1 ·
I bought the JK Leak Tester from Mach V and when I do a leak test it only registers 2 psi on the boost gauge (Autometer), and it sounds as if all the air is leaking out of the turbo itself. I noticed that the turbo outlet pipe had no gasket, so I made one, and that didn't fix anything. Bummer cause I was so excited that I had found the leak.
I've tried turning over the motor to different positions (I didn't have the tools on hand to jack the car up and turn the motor by hand to TDC), but to no avail. I did notice that if I cover the exhaust tips with my hands that I am holding back a small amount of air, so I guess there is some going in to the cylinders. Maybe the air leak I'm hearing is just the air going straight through the motor and back out of the exhaust?
Here's one thing that I'm curious about...maybe the compressor is too small? It's normally used for pumping up tires, but it does have a regulator on it that says it goes to 100 psi. I tried 100 psi, and my gauge still read 2. I've got the MBC disconnected, and I just ran a hose from the turbo outlet nipple to the wastegate actuator.
The reason I think I have a leak is because my boost falls off at high RPM from 14 psi to 13, then finally to 12. And my turbo is very "wheezy" sounding. I know this may be because it's tired, but if there's a big leak then that also means its spinning way faster than it should be to push 14 psi.
So, my main question is what part of the turbo can leak air? Or am I just unlucky and keep getting my motor in a position where it is leaking all the air out?
Maybe next week I'll bring my breaker bar and jack to my cousins house where the compressor is so I can get the motor at TDC. BTW, if it reads TDC on the timing marks, does that mean its at Cyl #1, or any random Cylinder? Does it matter which one's at TDC?

Thanks for reading all that!! :D
 
#2 ·
im not too familiar with how exactly you do a leak test but i can answer a few of your questions. First, i'd try leaving the mbc connected and to what you have it set too, which is 15 psi im guessing from what you said about it falling off. With the output elbow directly connected to the waste gate it takes very little pressure for it to open and leak off your boost. As for the boost falling off, i dont really know. I do know sometimes when you get way up there especially with like a T-25 it cant keep up with all the air coming in and it falls off, but your 1g probably shouldnt be doing it. And if the timing marks line up cyl. #1 is TDC. I hope that helps a little
 
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Discussion starter · #3 ·
Well i've tried leaving the MBC connected, leaving the BCS connected in stock form, running a hose from the turbo outlet to wastegate actuator, and capping off the nipple on the turbo outlet. They all yielded the same results, except when the MBC was connected it leaked air from the bleed hole (Hallman Classic MBC), which I think is normal, unless somebody can inform me otherwise.
 
#4 ·
did you check if you capped off the nipple on the turbo under the intake inlet, when i installe my mbc i forgot to do that and when i went to pressure test it alot of air would leak right out of there and wouldnt read any boost on the boost gauge when testing it.
 
Discussion starter · #5 ·
i'm not sure i know which nipple you're talking about. maybe that's only on T25's? (Mine's a 1G with a 14b) Or if there is something like that which I'm not seeing that would be a nice easy fix! hehehe
 
Discussion starter · #7 ·
The only nipple that i've seen down there is on the wastegate actuator. Are you talking about one directly on the compressor housing? (you said turbine housing but i'm assuming you meant compressor housing)
 
#8 ·
If you have a stock 14b and outlet pipe then, there is a very small tube on the turbo's outlet that comes out towards the hood and bends 90 degrees towards the fans.
Image


If you have a 2G car with a T25, then the tube is tapped right into the compessor housing.
Image

That tube is the pressure signal for the wastegate actuator. Make sure that this tube is plugged or re-circulated back into somewhere on the car's intake. I took that tube and sent it right to the wastegate actuator and when you pressurize the intake during the test, it will cause the wastegate actuator to open the wastegate. Since there is no air to release in the turbine housing, nothing happens and you have no intake leak from it.

Make sure to check: the blow off valve and it's vaccum line, all hoses going into or out of the throttle body, the hose on the factory air canister and the hose to the little boost control solenoid that is attached to the air canister.

Also, go here to see other ways to reduce the mess of factory hoses that can cause leaks.

http://www.taboospeedshop.com/emissions.htm

Good Luck.
 
Discussion starter · #9 ·
Good example!!
OK, so I will plug the turbo outlet pipe's nipple next time. I've already cleaned up the vacuum hose mess a while back when I first got the car, so that's not a concern anymore. But since I'm still trying to trace down a leak at the turbo, I haven't gotten to the BOV or anything else upstream yet. I can't wait til next week when I can turn the motor to TDC and see if that's what was causing my 'leak'!! :cool:
 
#10 ·
bgilly said:
Good example!!
OK, so I will plug the turbo outlet pipe's nipple next time. I've already cleaned up the vacuum hose mess a while back when I first got the car, so that's not a concern anymore. But since I'm still trying to trace down a leak at the turbo, I haven't gotten to the BOV or anything else upstream yet. I can't wait til next week when I can turn the motor to TDC and see if that's what was causing my 'leak'!! :cool:
Click to expand...
Try tightening the band clamp that holds the center section of the turbo to the turbine housing. Sometimes it is a little bit loose and that produces a leak. BTW it is hold together by a 10mm bolt...;)
 
Discussion starter · #11 ·
Blackboost said:
BTW it is hold together by a 10mm bolt...;)
Click to expand...

I was reading through the beginning of your post, and I was thinking to myself "damn it! now I'm gonna have to ask him what to adjust it with!" hehehehe And then of course you go on to tell me what to use. Psychic I tell ya! :D
Thanks dude!
 
Discussion starter · #12 ·
oh shit, i'm gonna have to pull off the heatshields to get to that bandclamp aren't i? damn bolts are stuck on like you wouldn't believe. i'll just bust out the breaker bar and wd-40 and see what happens i guess.
 
#13 ·
bgilly said:
oh shit, i'm gonna have to pull off the heatshields to get to that bandclamp aren't i? damn bolts are stuck on like you wouldn't believe. i'll just bust out the breaker bar and wd-40 and see what happens i guess.
Click to expand...
I don't think that you have to do that. The bolt of the band clamp can be located on the bottom part of the center section, right next to the turbo oil return line...
 
Discussion starter · #14 ·
cool, i really hope that's it. if it is tight, then what else should i look for there? maybe its something that's internal to the turbo that's letting the air out?
 
#15 ·
Just finished my leak test just now.
I also only had 2-3 PSI on my boost gauge and compressor set to 100 PSI. At first i thought the tester was too big for the 14B cuz i felt leaks all around it. I tightened it some more and still leaks. Ended up being the gasket on my J pipe to turbo outlet. Tested it again and no more leaks...Boost went up to 15PSI. Just make sure there is no air coming from around the turbo intake and around the J pipe. Good luck
 
#16 ·
Hei bgilly, I was trying to pressurize the thing a few days ago and got no pressure at all. Probably got confused in all the hoses and didn't cap off all I needed to. Was doing it around 7 P.M. and it was getting dark. Can I join you for your next try? Where are you in L.A?
 
#17 ·
Hey i've been having wierd results with a boost leak tes..i was gonna make a new thread until i found this one. I can build about 5-6 psi, and i hear a leak coming out from the gasket under the valve cover (head gasket?). I know this is where it is coming from because when i move my finger across it, i can hear the air flow (leak) being disrupted. Do i need a new gasket? If so, what gasket is that (I know im a newb at this car thing). Thanks alot!
BTW i just tightened my JoeP down almost all the way and it stopped the mbs from leaking..
 
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#18 ·
if you mean on the turbo side of the engine.... the head gasket would be about and inch below the exhaust ports. if that's leaking it's really bad. don't run the car, get it fixed or you'll be paying alot more thatn you might hvae to right now.

as for the boost leak... what about the O-ring between the compressor housing and the turbo center cartridge?... that tends to get crusty after a while and can easily leak alot of pressure if it's cracked.
go to www.vfaq.com and look at the vfaq for a turbo rebuild to see how to change it. if not that... why don't you take the upper ic pipe off the tb elbow and cap it off and just test that part of the system... that way you know it's not leaking through the motor... then if you want you can put the tester right on the tb elbow and test the intake mani. and the motor separate..
just some ideas to mess with.
 
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#19 ·
I figure out my leak is the valve cover gasket. However, there is a black semi circle type thing right below where the leak is, the semi circle sticks out farther than the rest of the engine by a mm or so...is this some kind of "weep hole" or vent of any kind? Thanks for the help!
 
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#20 ·
FlaToUt-GST said:
I figure out my leak is the valve cover gasket. However, there is a black semi circle type thing right below where the leak is, the semi circle sticks out farther than the rest of the engine by a mm or so...is this some kind of "weep hole" or vent of any kind? Thanks for the help!
Click to expand...

That's the half moon seal...;)
 
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bgilly
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