Garrett T28 home rebuild...

Here's a few pictures of fixing up a used and abused Garrett T28 journal bearing turbo from a 3.1 LG5 engine. This was part of a Chevy Celebrity Eurosport Turbo build on another forum. Figure it would be interesting here.

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First, off with the compressor housing. That snap ring is a bear to remove. Had to heat the housing area to soften the o-ring and help things get moving. I did not mark the orientation of the housing, because I was not satisfied with it. I will find a new better position when it goes back on the car. The air hose was in an "uncomfortable" position.
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I did mark the turbine housing orientation. That one has to be same, or the tubelines won't fit.
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CHRA out of the housings. Removal of the turbine housing the first time (during initial turbo system build) was VERY hard, requiring heating and use of hydraulic expanding "duckbill" thingy. This time it just came off normally.
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I blasted the impeller and turbine with glass beads before dismantling. There are factory markings on them which were covered in ash. I marked the housin with a very shallow scribe line, and made note of which factory marking lined up with this. This way I can ensure the oritntation of the shaft and compressor wheel is the same. Also marked the shaft nut with a scribe line because it is balanced with the other parts and needs to be torqued to exactly the same position. This is for maintaining the balance of the unit.
This part is critical. The turbo shaft must absolutely not be subject to any side loading. It can not tolerate any bending. The only way to remove the nut is to support the end of the turbine wheel and the nut its self. The housing can NOT be used for any support or leverage during the torquing or removal. Doing so will ruin the turbo. The nut is insanely tight for such a small part.
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Impeller off.
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This part did not want to come off. I had already plugged the oil ports so that blasting media could not go in the turbo. I just applied air to the oil port after removing the snap ring. It was LOUD and that cover went flying!!!:p
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Shaft out.
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The bearings. New and old. You can see the damage caused by the contaminated oil. :(
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New thrust bearing. It's a different design. The original one had a one-piece journal and an open side to the thrust bearing. The new one has a two-piece journal and a 360° thrust bearing.
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This is it for today. Parts cleaned up, but the bearing housing is in a chemical bath overnight. I don't want to risk getting blasting media inside it, but the crud in there has to go. So it will have to soak overnight.
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Ok here's the rest of the turbo repair pictures. The center housing was soaking in EvapoRust overnight. This stuff is exellent. It won't damage or affect anything other than rust. I was skeptical that it would work, seeing how "safe" it claims to be. But it is badass. If you use it as directed (there is a temperature requirement) it really works.
The product:
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The result:
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And there is no chance of leaving blast media in the housing.
Next the bearings and shaft go back in.
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Then the inner part of the thrust bearing journal.
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Then the thrust bearing plate. The outer part of the thrust bearing journal is assembled to the cover, ready to go on.
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Then that assembly slides in and the snap ring goes in. It's a tapered ring to keep vibration to a minimum. Therefore it must be firmly seated by expanding it and tapping on it. As the o-ring compresses, the ring expands into the groove, locking the cover in place.
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Now for the alignment of the parts, for balance reasons. Look at the turbine wheel. See the number "510" between the 2 blades. One slot to the left, there is a round dot cast into the wheel. This aligns to the drill mark on the housing flange. This was the position before teardown.
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The compressor end has an "A" logo (for Airesearch). The first blade to the right (viewed normally) lines up with the scribe mark on the housing.
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Then the nut goes on, and tightens to the original position, by lining up the scribe marks placed on them earlier. The mark on the compressor wheel is very small to avoid damaging the wheel. I dotted black Sharpie pen over them to help with visibility.
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Finished CHRA.
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Now to clean the ash and carbon out of the turbine housing. Wire brush wrapped in Scotch Brite works well.
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Result:
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Install the clamps with antiseize on the bolts. Line up the drill mark and tighten it.
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No carbon in there.
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Compressor o-ring
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This snapring is a tapered ring to compress the o-ring as it wedges into the slot. It's important to expand it forcefully and tap the housings. This will make sure the o-ring is compressed and the housing is fully seated.
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Completed turbo!
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I forgot to take pictures, but I had to re-drill the actuator bracket mounting holes. They are threaded into the compressor housing. I rotated the housing to give the air hose a less strained alignment with the charge air pipe on the car body. After that, the actuator holes didn't line up. It took a trip to the store to get a M6x1.0 tap set and a 5mm drill bit. But it will be worth it when the car goes back together.
 
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