14b leaking like crazy during boost leak test

[vintagemuscle]

first off, the 14b has zero shaft play and there is no sign of it leaking oil. the problem is when doing a boost leak test, applying air pressure to the compressor housing it leaks air like crazy. i can build pressure to about 15psi but it all leaks out of the turbo within 15 seconds. i can hear and feel the air coming out of the turbo but cannot pinpoint the leak. for some reason it feels like it is coming out where the turbine housing connects. is this even possible? when testing on the licp i can build as much pressure as i want and it doesn't leak down very fast at all. when pressurizing from the turbo i can hear a strange sound under the valve cover that sounds exactly like a heart beat? i have a rebuilt head with new valve seals and compression #'s are decent. does this mean the turbo seals are bad and i need a new turbo? is there any possibility this could cause me to have such low vacuum readings (10in.) and stalling everytime i come to a stop? i have tried everything to fix this problem short of a rebuild:
all boost leaks fixed
isc replaced
new o2 sensor
ecu checked
valve seals
valve guides
all new gaskets
fiav blocked off

somebody please help, this is driving me crazy.

 

[Stapl3]

There's seals in the turbo that go bad. You can pull it apart and put it back together, but then you run into a gamble with the balancing.

Time for a different one.

 

[erebusknight]

true that! go for an EVO III. The stalling issues may be the air not coming in. Any open spot after the MAF is considered false air. Check all of your small vacuum hoses.

 

[Dream On]

I would try using soapy water all over everything to see exactly where it's coming from.

 

[vintagemuscle]

thanks guys. every other leak has been fixed and all vacuum hoses have been replaced. i do have a very tiny leak between the tb and intake which will be fixed asap. i guess it's time for a 50trim.

 

[vintagemuscle]

I would try using soapy water all over everything to see exactly where it's coming from.

i tried that and it's still hard to tell but now i know for sure it is leaking where the turbine housing connects to the cartridge.

 

[vintagemuscle]

to completely rule out everything but the turbo that is causing my stalling problems could i simply place the intake pipe and mas on the tb elbow and see how it runs. (of course not boosting). i would think this would be a good way to confirm a bad turbo seal. is there anything wrong with doing this?

 

[PieEyedPiper]

I dont know anything about that so i wont condone it (though on paper and your MAS is still hooked up I dont see why not).
BUT!! No one has mentioned that upon actual operation of the vehicle the turbo seals work MUCH better because of oil pressure and such (ok i dont kaow EXACTLY why ).
I never bother testing form the comp housing because I know it will never build as much pressure since the seals let air by when the engine is not running.
I think if you can build 15 psi at all at the comp cover your seals are in fairly decent shape. Are you blowing smoke? (a sign of seal failure).

I test at the intercooler inlet and I can hold 22psi for about 25-35 seconds before I'm sitting at only a few psi and eventually zero.
This is the ideal result.

 

[vintagemuscle]

no, i'm not blowing any smoke, or burning any oil. i also am skeptical that a turbo seal could have such an impact on vacuum and afr but i really am running out of options. i have had this car for almost a year now and i just can't get it to stop stalling. i have replaced everything short of a total rebuild but nothing seems to help. in 11 months that i've owned the car i've driven it a total of 500 miles.

 

[Stapl3]

I have personally have a 14b with the exact leak you are speaking of. Oil pressure has nothing to do with it. It leaks pressure or not.


Yes, you can hook your MAS directly to your TB elbow.

 

[91-gsx]

i had the same problem with my 14b before i rebuilt it. i have not been able to drive the car yet due to a blown head gasket but when i first did a leak test, the 14b was doing the exact same thing as yours. when i rebuilt the turbo, the seal on the cold side of the turbo was old and had cracked which caused the leak. if you want to replace this part of the turbo, you do not have to take the whole turbo apart. you simply take the turbo off the car, remove the circlip holding the cold side in place and pop off the cold side of the turbo. once this is done the gasket can be replaced and everything put back without rebalancing because you did not remove the wheels or anything else that has to do with the balance of the turbo.
later

 

[ITSME4G63]

why dont you tickten the bolt on the clip that holds the turbine housing and cartirdge together? maybe ti jsut got loose from vibrations or whatever. It may be your exhaust housign leaking too, maybe there is a crack or somethign in it. I have one sitting around that has cracks to shit,and is off of a 16g, so its possible. But if youre getting a 16g turbo, id opt for a evo or the turbochargers.com turbo, there are 3 evo 3 turbo copies/knockoffs, turbochargers.com actually get a good turbo made, yes overseas but its good, already has the turbine housing cast open so big that it doesnt have to be ported out and has the larger flapper on it if needed.

 

[vintagemuscle]

i'm planning on just going 50 trim since i have an external gate and most of the supporting mods. maybe i will replace the seal and sell it since it's in perfect shape. what i have discovered is that the reason i have been running lean is due to a hacked 1g mas. i'm not quite sure yet if this is the problem but when i blocked half of the lower part of the mas with duct tape my o2 readings began to fluctuate like normal and my car no longer stalls. the mas on my car should be fine with just the lower honeycomb removed but for some reason it makes my car run very lean at idle. this fix may just be masking my problem though. i have another 1g mas that has both honeycombs removed and the car runs the same with both of them.

 

[Ian M]

the seal on the cold side of the turbo was old and had cracked which caused the leak.

Yep,there is a rubber o-ring that goes in a groove in the CHRA. Everyone I have seen is squashed flat and hard as a rock. I am not sure if it is availible from Mitsubishi as a replacement part,but I used a regular 0-ring.