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Old 05-23-2010, 09:55 PM   #1
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Default T25 Rebuild

Hey guys,

So I've finally disassembled everything to take apart my turbo and rebuild it. It is an SR20 T25. I've read and compared notes of about 4 to 5 T25 rebuild articles and I have a few questions due to the discrepancies in the articles and the way my failed turbo was assembled. Mostly regarding the outer snap ring holding the turbine bushing in. Do I use a C-ring or that coiled piece of metal? Does the oil deflector plate (washer type thing) go on the inside or outside of the final retaining ring?

Which way is the right way?

1.
I disassembled mine and starting from the inside it was c-ring, bushing, oil deflector, coiled retainer.

2.
Brain's write-up states Funky wavy clip (c-ring), Gold bearing (bushing) Funky retaining clip (coiled retainer). No mention of the oil deflector being inserted here, but I believe he put it on the outside of the coiled retainer.
https://www.miataturbo.net/useful-saved-posts-8/rebuilding-t25-turbo-10996/

3.
This image shows that a c-ring is used and the oil deflector is on the outer. Part #2 and #3 on the turbine side. Not exactly sure what part #4 is.


4.
This guy does c-ring, bushing, c-ring, oil deflector and coiled retainer on the shaft. This guy is also a car guru in my area.


5.
This guy does it the same way I disassembled mine




I'm a bit worried that my CHRA/bearing housing will be damaged after seeing the scoring on my bushings. Do these bushings freely spin during normal operation? Yes, some holes are filled with molten metal
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Old 05-23-2010, 10:13 PM   #2
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I can't answer most of your questions since I have never rebuilt one, but I can tell you that these journal bearing turbos do not freely spin. Like you can move them with your finger, but if you give them a quick twirl they will quickly stop.
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Old 05-23-2010, 10:20 PM   #3
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Quote:
Originally Posted by dustinb View Post
I can't answer most of your questions since I have never rebuilt one, but I can tell you that these journal bearing turbos do not freely spin. Like you can move them with your finger, but if you give them a quick twirl they will quickly stop.
That question about freely spinning was actually meant for the actual bushing itself and not the entire shaft. Are the gold colored bushings supposed to spin within the housing, or is the shaft supposed to spin within the bushing...or both?

Thanks.
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Old 05-24-2010, 02:33 PM   #4
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Anyone have input on this?
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Old 05-24-2010, 04:03 PM   #5
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I doubt they are supposed to spin in the housing, because then the housing would be come a wear item as well as the shaft and bushing which would defeat the whole purpose of using a Bronze bushing as a sacrificial Metal ment to be replaced

I'd say the turbo got starved of oil or was overspun to do that damage
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Old 05-24-2010, 05:49 PM   #6
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Quote:
Originally Posted by Rotaryman View Post
I doubt they are supposed to spin in the housing, because then the housing would be come a wear item as well as the shaft and bushing which would defeat the whole purpose of using a Bronze bushing as a sacrificial Metal ment to be replaced

I'd say the turbo got starved of oil or was overspun to do that damage
^ This... the shaft should rotate in the bearing, not the bearing in the housing.
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Old 05-24-2010, 06:09 PM   #7
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Bearings just push in and are not a tight fit. They are held in place with the c clips. If you have too much wear they may spin in the body if they are not a snug fit.
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Old 05-24-2010, 08:07 PM   #8
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Thanks. Anyone know about the rest of my first post?
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Old 05-25-2010, 07:17 PM   #9
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Anyone?
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Old 05-27-2010, 10:00 AM   #10
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Come on, someone must have rebuilt a couple T25s
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Old 05-27-2010, 02:01 PM   #11
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My kit did not come with the oil deflector washer. Anyone know what size it is so I can just go buy one? Does this seal the oil in, or is it just a spacer?

The loose looking washer on the shaft from Brain's pic

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Old 05-27-2010, 04:13 PM   #12
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Quote:
Originally Posted by dgmorr View Post
My kit did not come with the oil deflector washer. Anyone know what size it is so I can just go buy one? Does this seal the oil in, or is it just a spacer?

The loose looking washer on the shaft from Brain's pic

I have rebuilt my 5th turbo last night, and my kits never came with that either, but I successfully rebuilt all my turbos anyways. I bought a Garrett SR20 T25 off this site that has seen better days, it was loaded with carbon and scarred journal bearings, but the stock internals never had that deflector when I tore it apart. Put the new goodies in and runs like a champ @ already 1k miles since I installed it.
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Old 05-27-2010, 04:19 PM   #13
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I'm pretty sure mine didn't have that washer either. The piston ring is what seals the oil out i'm pretty sure. Make sure that snaps in nicely and you'll be set.
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Old 05-27-2010, 04:21 PM   #14
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In my head it would prevent excessive oil from spraying out the piston ring...but I've never done this before.
So from the turbine wheel in, it's - piston ring, c-ring, bearing, c-ring? What does the seal plate on the exhaust side seal in, and how is it even held on?

Penguin, you didn't use the washer on all of your previous rebuilds either?

If you guys say so...I'm just a noob, so I'll follow what the old guys say.
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Old 05-27-2010, 04:22 PM   #15
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Again, i'm pretty sure (but not certain) that I didn't have that washer and 2 years later my turbo doesn't leak a bit of oil.

\Your logic is spot on, it does seem to make sense having it there..
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Old 05-27-2010, 04:57 PM   #16
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Quote:
Originally Posted by dgmorr View Post
In my head it would prevent excessive oil from spraying out the piston ring...but I've never done this before.
So from the turbine wheel in, it's - piston ring, c-ring, bearing, c-ring? What does the seal plate on the exhaust side seal in, and how is it even held on?

Penguin, you didn't use the washer on all of your previous rebuilds either?

If you guys say so...I'm just a noob, so I'll follow what the old guys say.
Nope, none were even found in the original parts. None that are installed in running cars leak either. You have to remember, there should be no spraying, since its a low pressure system. It basically pours oil into the turbo, not force.
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Old 05-27-2010, 05:23 PM   #17
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It's anywhere from 15-80psi, at least on my gauge measured at my oil filter adapter. I'll put it back on the car tomorrow and hope I can just drive again.
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