did a boost leak test

[NixHex]

i used my home depot leak detector to do a boost leak test on my intake and heard bubbling in my oil. i took off the oil fill cap on the valve cover and could hear it really well. am i right in assuming that its blowing oil through the turbo seals and out the turbo oil line? thanks much for any advice.

 

[sonicnofadz]

Unfortunately you are not going to be able to diagnose a blown turbo with a boost leak test. You are pressurizing your intake, so air is potentially also getting into your cylinders, and it could be traveling past your rings (if your rings are really worn) and into your oil. Is your exhaust smoking badly?

 

[ChvyKc]

Run a compression test on the motor to see how each cylinder is holding up. That's one good way of telling how good the bottom end is holding up. If you come back with good compression then there is another problem (possibly the turbo).

 

[alex]

I dont know if this is 100% correct, but it sounds like either you have bent valves, or you just might want to get a new head gasket. Like "ChvyKc" said, do a compression test on the engine. After you have done that, let us know what the results were.

-Alex

 

[oldman]

i used my home depot leak detector to do a boost leak test on my intake and heard bubbling in my oil. i took off the oil fill cap on the valve cover and could hear it really well. am i right in assuming that its blowing oil through the turbo seals and out the turbo oil line? thanks much for any advice.

You are correct, the oil bubbling sound is pressure getting through the turbo, return line, to the oil pan. This is normal during a static intake pressure test partly due to lack of oil pressure in the CHRA, what is a problem is if you see oil in your licp and ic or blowing smoke out of your exhaust. Move your tester to the licp bypassing the turbo, if you still hear hissing under the oil cap, you then need to look into pcv, valve seals/worn guides or piston rings.

I dont know if this is 100% correct, but it sounds like either you have bent valves

Alex, bent valves will not cause air to leak into the crankcase unless the valve guides were also taken out in the process.

 

[ChvyKc]

Alex, bent valves will not cause air to leak into the crankcase unless the valve guides were also taken out in the process.

That's what I was thinking, beat me to it.

 

[NixHex]

Is there any danger in me driving with bad turbo seals and pressurizing the crankcase? Also I was wondering what were the differences between the stock t25 and the t28. If its just the wheels used where can i buy them. If there are other differences do tell. Thanks for all your help.

 

[oldman]

Is there any danger in me driving with bad turbo seals and pressurizing the crankcase?

Like I said before, you can't determine if the turbo seal is bad or not using a boost leak test, this happens to most when performing a static pressure test. To determine if the turbo seal is bad, you need to pull the licp and check for excessive oil.

Also I was wondering what were the differences between the stock t25 and the t28. If its just the wheels used where can i buy them. If there are other differences do tell.

You can't just buy different compressor wheel and slap it on the T25 without blancing, well you can but don't expect the turbo to last.

What exactly led you to the leak test in the first place?

 

[SBstar]

Not trying to discourage further checking, but I would replace the pcv first and then go from there, when I did my first check I blew air out my dipstick and replacing the pcv fixed my problem.

 

[NixHex]

I realize you cant replace the turbo wheels without balancing. If I took the turbo off the car I'd rebuild it and if possible convert it to a t28 but I didnt know what it takes to convert to a t28. I just took off the licp and there is quite a bit of oil in there. I did another boost leak test from the licp and there is still hissing under the oil cap. so I hope its the pcv. I'll update when I test the pcv.

 

[oldman]

I just took off the licp and there is quite a bit of oil in there. I did another boost leak test from the licp and there is still hissing under the oil cap. so I hope its the pcv. I'll update when I test the pcv.

1. Are you blowing smoke under boost or letting off?

2. Is your breather valve from the valve cover still routed back to the intake pipe?

3. How much is quite a bit?

I'm not familiar with T25 to T28 rebuild conversion so someone else will have to help you with that.

 

[NixHex]

1.) I get a puff of smoke under heavy throttle and no other time to my knowledge.
2.) Everything is stock so the breather is still going to the intake pipe.
3.) There is enough oil in the licp to wet my fingers with it but i dont know how to measure it .

I tested the old pcv valve and it jingles like crazy. Air flows fine from valve cover to intake, but air also goes through it from intake to valve cover. I bought a knew one and the knew one wont let any air through the intake to valve cover side so hopefully thats it. I'll test again and then update.

 

[oldman]

1.) I get a puff of smoke under heavy throttle and no other time to my knowledge.
2.) Everything is stock so the breather is still going to the intake pipe.
3.) There is enough oil in the licp to wet my fingers with it but i dont know how to measure it .

If the oil in licp was from the turbo seal, there should be at least half a quart on the bottom of your IC. If it's just a thin layer on the pipe walls, it's probably blow by from the breather.

I tested the old pcv valve and it jingles like crazy. Air flows fine from valve cover to intake, but air also goes through it from intake to valve cover. I bought a knew one and the knew one wont let any air through the intake to valve cover side so hopefully thats it. I'll test again and then update.

Make sure you replace it with a true OEM piece, not aftermarket ones from any autoparts stores.

 

[NixHex]

I just replaced it with an auto zone one. It was cheap in a few days ill get an oem one. thanks for the help.

 

[oldman]

Make sure you do that, non-OEM ones are known to leak right out of the box (Even an OEM unit is no guarantee). Also, just because it sealed when you blow into it doesn't mean it won't leak under real pressure. the blow test is good for detecting obvious bad ones but not so when confirming a good one.

 

[SBstar]

OEM ones are only 11 bucks anyways.