Turbo rebuild: Do I need a new turbine wheel?

[lasthope05]

With FP's recent turbo sale, I recently picked up a 3794hta, which should be coming this wednesday, for my new setup. Since I currently have the time I took off my good ole HX40 and decided to tear it down completely to see how she's doing. The turbo has over 100k miles and was still in pretty good condition. Bearings were great, shaft looked decent but the thrust collar looked iffy and the turbine wheel obviously has some damage.

What causes this type of damage to the turbine wheel? It almost looks like its flaking. And do you think I'll need a new wheel?

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What do you think of the thrust collar? Does it seem like normal wear? The thrust bearing is perfect. No markings or burn at all, however, the thrust collar to me looks a bit worn/over heated. Can the thrust collar over heat but the bearing be perfectly fine?

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[bastarddsm]

looks like somthing went through the turbine. The journal bearings look ok. See if they polish up with some grey scotchbrite and wd40. The thrust does look funky, rub a penny on it and see if it leaves copper. It does.... Lay a piece of 600 grit paper on the thrust bearing, then push the thrust collar thru the paper. Lube with wd40 and polish with a twisting motion.

 

[lasthope05]

With the turbine wheel the damage is on all the blades. I figure if it was some debris the fins would actually bent or chipped. I cant see debris damaging that deep into the blades without destroying the fins.

I'll try lightly polishing the the thrust collar and see if any surface markings go away. There are 2-3 light scratches I can see from contaminated oil but thats all, nothing too serious.

 

[CanadianTalonTC]

Do you use launch control?

Joel

 

[lasthope05]

Do you use launch control?

Joel

2 step only, no antilag.



I did lightly polish/scuff the thrust bearing and the coloring was just superficial. That just leaves the turbine wheel.

 

[Boostdriven]

From the looks of it I think your turbine wheel is just fine. The flaking that you see is just carbon buildup, I bet if you took a razor blade you would be able to scrape it off the wheel, I've seen that before. If you really want to get technical with cleaning up this turbo then you can scrape all that buildup off but do it carefully and make sure to remove all of it. Use some scotch bright pad and WD40 to clean it up the rest.

If the bearings are good then I would just replace the piston ring on the exhaust side. You can buy a piston ring from www.baeturbosystems.com or some other vendor. Make sure to clean out the piston ring grove of all the carbon buildup. I usually use the old piston ring to carefully scrape out the grove. After you do that take a short piece of hose (2" or so) that fits tightly over the turbine shaft on the compressor side and slide it on to the shaft and put the other end of the hose in to a drill. Take some scotch bright and pray it with WD40 and wrap it around the shaft then spin the drill polishing out the shaft. Do the same thing to the piston ring section and you will end up with a brand new looking shaft.

Thrust bearing looks just fine, you can clean it up a bit with WD40 and scotch bright to smooth out any groves. You can take a small bolt that will fit through the thrust coller and lightly lock it down with a nut then put the bolt in a drill so you can spin the coller. Again use some scotch bright and WD40 to clean up the scored area of the thrust coller. Don't worry to much about the groves, just clean it up a bit and you will be fine. To clean up the front piece if the thrust coller that has a piston ring on it you can just take some 1200-1500 grit sand paper and lay it on something flat. Spray some WD40 on the sand paper then gently in the circular motion sand the flat side of the thrust coller on the sand paper, don't put to much pressure on the coller as you send it, all you want to do is smooth it out and not remove to much material.

Another thing I like to do is switch out the bearings, compressor side with exhaust side. Exhaust side bearing usually wears out faster then compressor side so if you switch them around you might get a little more life out of the turbo. It wouldn't hurt to polish out the bearings with some scotch bright and WD40 on the inside and outside. If this turbo has never been rebuilt make sure you out the snap rings that hold the bearing in place in the position as they come out. I usually install the snap rings with the open end down towards the drain side of the CHRA. The split end of the piston rings on both the compressor side and the exhaust side need to point to the top of the CHRA, towards the feed side of the turbo. If you put the spilt end down the turbo might smoke.

I've done this to several turbos with out giving them a full rebuild with good results.

 

[JusMX141]

Turbine looks fine to me- needs media-blasted to get rid of the carbon / oil coking, but that's all I see.

 

[Boostdriven]

Turbine looks fine to me- needs media-blasted to get rid of the carbon / oil coking, but that's all I see.

I wish I had a media-blaster then time consuming razor blade job would be avoided

 

[donniekak]

Methylene chloride (aircraft stripper aerosol can) is great at removing carbon.

 

[lasthope05]

Thanks for the responses guys. I was just concerned about the flaking I saw as being an erosion problem and if it would continue degrade. I just took a razor blade to it and it was just white carbon build up so thats good to know.

The internals looked great on the turbo considering the hard life it had and doesnt look like it'll need the rebuild but I already have the kit so I might as well throw it on there.

 

[JusMX141]

Unless your parts kit is OEM Holset, definitely consider re-using the factory thrust hardware. The aftermarket stuff just doesn't hold up from what I've found.