BLT oil bubble.. turbo seal question

[razrman8]

Performed a blt. And I hear a glug glug noise as if there there is bubbling going on in my oil. Which leads me to think my turbo seals bad. If it is would there be more signs of it being bad. I noticed that I don't think that its boosting As high as it used to . It boost to 9-10 is that stock .. I run no bc at all If It is how hard is it to replace? How do I got about it

 

[Colt4G63 also]

It's normal for some air to escape past the turbo seals and bubble out of the oil return. It's also normal for your car to boost different pressures depending on ambient air temps.

You can feel free to worry about something else.

 

[JusMX141]

Our turbos all use a dynamic seal on the compressor side. A dynamic seal is nothing more than a small piston ring with a grooved collar which turns inside the seal.

As we all know, piston rings do not seal 100%....neither do dynamic seals. Even a brand new turbo is going to bleed a certain amount of crankcase pressure.

The only turbos that have a 100% airtight seal on the compressor side are some older Garretts using a carbon seal. The carbon seal is the only type of seal suitable for draw-through (carbureted) applications.

 

[Sp1kE]

I had problems with this on my car having crazy amounts of blow by on a fresh motor and fresh rebuilt turbo and everyone gave me those answers, thats normal, blah blah, just get bigger valve cover vents, blah blah.
There is a dynamic seal around the shaft, so very small amounts of air WILL past through.
BUT
There is also a pressure fit rubber O ring.
On my Holset that I just rebuilt, (also a journal bearing) there is a C clip that pushes on a "cap" to make the seal on the o-ring to housing.
There was not enough pressure pushing down on the cap/oring.. or something to that matter which made boost push right past that rubber o-ring.
I ended up dipping the o-ring in rtv making sure it was completely coated and placing it in its groove on the turbo. Let it dry a bit then put the cap on with c-clip.
Let that dry for 12 hours and BINGO no more "blow by"!

here is a video of the air dumping out the drain.
YouTube - Holset Hy-35 pressurizing the crank case through the oil drain.

 

[razrman8]

So having that is not put of the normal ? Can you explain why I have air that comes through my top line on that solenoid ? It's not much. I just block it so I can here everything else

 

[Colt4G63 also]

OP, your last post is jibberish, and trust us, it's normal for your dynamic seal to leak a small amount of air when you BLT. You have an EIII right? Not a holset or a Garret with a carbon seal? Brand new ones do the exact same thing.

 

[razrman8]

OP, your last post is jibberish, and trust us, it's normal for your dynamic seal to leak a small amount of air when you BLT. You have an EIII right? Not a holset or a Garret with a carbon seal? Brand new ones do the exact same thing.

Excuse the typo's for I was at work doing this all from my EVO. But, as far as the turbo, I am running the stock t-25 not a e316g. So pretty sure there is no carbon seal action going on here. After I have set back and thought about the issue, I began to wonder if my blow off valve is causing me problems with the boosting. So, in the morning I am getting my friends Type-S from him to see.

 

[JusMX141]

It's unusual that a T25 will leak boost pressure on the compressor side without having a lot of shaft play. If there is shaft play, then there's a good chance you'll get some excessive blowby- and the turbo will either need rebuilt or replaced as a result.

For the record- if there is in/out play, the compressor seal moves with the collar so it will stay sealed while the turbine seal stays fixed in the housing and the shaft moves within the seal, wearing the seal wafer-thin. If there is a lot of up/down play, it tends to egg out the compressor seal collar and allow air to pass by.

 

[razrman8]

It's unusual that a T25 will leak boost pressure on the compressor side without having a lot of shaft play. If there is shaft play, then there's a good chance you'll get some excessive blowby- and the turbo will either need rebuilt or replaced as a result.

For the record- if there is in/out play, the compressor seal moves with the collar so it will stay sealed while the turbine seal stays fixed in the housing and the shaft moves within the seal, wearing the seal wafer-thin. If there is a lot of up/down play, it tends to egg out the compressor seal collar and allow air to pass by.

I see. Well the turbo is in good shape. With minimal and I mean minimal play. I swapped this one in there because my old one was shot. I'm ashamed of myself for driving on the old turbo. I wish you guys could feel just how bad it was

 

[Sp1kE]

The turbo DOES NOT NEED to have shaft play for it to pressureize and blow air through to your crank case.

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If there is no shaft play but you are still getting alot of bubbles into your crank case then 100$ says that #10 in the picture above is not sealing right. If it is out of place, cracked, or hardned, that seal will let through a tonne more air then the dynamic seal would if the turbo had a large amount of shaft play.

My brand new seal that I put in there had enough pressure on both sides of it so it would not allow oil to seap past into the compressor side, but a small amount of boost (9psi) would push right around the seal and into the crank case.