K03 Turbo rebuild - hard to do? worth doing?

[egovreau]

So, as I survey my recently acquired B6 for what mods I want to do, I have come to the realization that there are things I'll likely have to replace or repair first. Some things are just a little out of the budget for the time being. I'm looking at doing a tune, most likely the Motoza stage 1 (the 1+ would be nice, but a FMIC and new injectors will need to wait). And because of their pricing, I'll only need to pay the upgrade price when I'm ready.

There is a possibility that I'll need to replace the turbo before too long (depending on what my oil leak/pcv/boost investigation reveals). I did some quick checking on rebuild kits and also in picking up a turbo at the junk yard. AND because I have a B5.5 Passat which uses the same turbo, I can pick up the extra one, rebuild it, swap in to the Passat or the A4 (whichever needs it first), then rebuild that one, giving me a spare to swap in right away, or hold until it's needed.

[DiertyEuroSpec]

Without being able to balance the turbo shaft with new compressor/turbine wheels, at speeds over 110,000 RPMS a rebuild on these turbos is futile.

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[egovreau]

Ah, okay. I didn't think of that. Thanks!

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[Kevin C]

Ah, okay. I didn't think of that. Thanks!

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If you just want to freshen a turbo that is in good working order, you mark the the location of the compressor wheel relative to the turbine. As long as you put them together with the same orientation, no rebalancing is needed ( some will still have it done) . If you need to replace the turbine or the compressor wheel you send the pair out for balancing. Typical balancing fee is $50 to $70. However, if your having to replace those parts, it's probably more cost effective to look for a good working used unit.

http://www.midwestturboconnection.co..._balancing.htm

On used units for my other turbo vehicle I always pulled them apart and freshened the internals before putting the unit in service. Either way, getting the parts balanced is not very expensive and lots of turbo shops will do it as a service. In 20 + years of running home rebuilt turbos, I have never had an issue with either method. It's a great chance to inspect for coking, scoring or worn parts as well put in new O rings in the cartridge.

[egovreau]

If you just want to freshen a turbo that is in good working order, you mark the the location of the compressor wheel relative to the turbine. As long as you put them together with the same orientation, no rebalancing is needed ( some will still have it done) . If you need to replace the turbine or the compressor wheel you send the pair out for balancing. Typical balancing fee is $50 to $70. However, if your having to replace those parts, it's probably more cost effective to look for a good working used unit.

http://www.midwestturboconnection.co..._balancing.htm

On used units for my other turbo vehicle I always pulled them apart and freshened the internals before putting the unit in service. Either way, getting the parts balanced is not very expensive and lots of turbo shops will do it as a service. In 20 + years of running home rebuilt turbos, I have never had an issue with either method. It's a great chance to inspect for coking, scoring or worn parts as well put in new O rings in the cartridge.

That's pretty much what I'm going for, really. To do a refresh...

[diagnosticator]

That's pretty much what I'm going for, really. To do a refresh...

Accurate re-balance of the rotating assembly is the most important aspect assuring a good running and reliable turbo, regardless of orienting the compressor impeller at the same angular position on the turbine shaft.

With the compressor impeller and the turbine both balanced separately, the rotating assembly will be balanced regardless of the final angular position of the impeller on the turbine shaft.

Having a torque wrench capable of accurately tightening the impeller nut to the specified value is crucial as well. The accuracy of the torque tool used must be known. With an uncalibrated torque tool, with unknown accuracy, the final torque value the nut is actually tightened to is also unknown.

The torque tool should be selected so that the specified torque value for the nut is within ~25% to ~75% of the full scale range of the torque tool for best accuracy.

Torque tools are available with the correct scale range value, with a certificate showing the tool is calibrated accurate withing a certain +/- % of full scale, and traceable to ASTM primary standards. $$

[texasboy21]

Purchasing a complete CHRA would be an option. It should be balanced from the mfg.

[Kevin C]

Accurate re-balance of the rotating assembly is the most important aspect assuring a good running and reliable turbo, regardless of orienting the compressor impeller at the same angular position on the turbine shaft.

With the compressor impeller and the turbine both balanced separately, the rotating assembly will be balanced regardless of the final angular position of the impeller on the turbine shaft.

Having a torque wrench capable of accurately tightening the impeller nut to the specified value is crucial as well. The accuracy of the torque tool used must be known. With an uncalibrated torque tool, with unknown accuracy, the final torque value the nut is actually tightened to is also unknown.

The torque tool should be selected so that the specified torque value for the nut is within ~25% to ~75% of the full scale range of the torque tool for best accuracy.

Torque tools are available with the correct scale range value, with a certificate showing the tool is calibrated accurate withing a certain +/- % of full scale, and traceable to ASTM primary standards. $$

An old school beam type wrench that is of the appropriate range is all I have ever used. Why use such a low tech tool? As long as the pointer is centered and not rubbing, its never loses its accuracy. The spring rate of the beam is a basic property of the material and won't change. No need to overthink this. Personal experience is that is all you need, that based on five or so units I have built up / freshened up since 1994 and no failures and a lot more units that friends have done.

Every set I have gotten balanced was marked for orientation, I'm not sure what your turbo shop has done on your rebuilds, but in my experience, not balancing the parts as a final assembly is considered poor practice. All shafts have run out, no matter how small an amount nothing is perfect. By ballance as an assembly with orientation, you can reduce that factor.

[Doug@FrankenTurbo]

Purchasing a complete CHRA would be an option. It should be balanced from the mfg.

Turbo International. Their CHRAs are Chinese (like ours are) but they have good quality and rebalance in the States (like we do).