0000a4T

is it tru that when you rebuild a ko3 it has to be balanced.because i dont want to pay the $500
to have it rebuilt i want to do it.

ben gt/cs

Borg Warner/KKK makes k03/k04 rebuild kits but im almost positive they have to be balanced properly as you said. Man, a rebuild doesnt cost $500 though, you can get a brand new turbo for that much. Try Majestic Turbochargers of Dallas Texas. They work wonders. I picked up my K04 from them and I'm gonna have it rebuild there.

diagnosticator1

the background experience to insure the successful completion of the work. (For example due to improper assembly, if the compressor impeller fails afterwards, there will be considerable engine damage as a result.)

After you take your turbo apart, take the turbine and the compressor impeller to a turbo rebuilder, (See "Fuel Injection, Diesel Engine" in the phone book.) The rebuilder shop will balance the turbine and the compressor impeller together with the impeller nut. Be sure that the position of the compressor impeller on the turbine shaft is marked with a magic marker before leaving the rebuilder shop, that's so that you will be able to realign the impeller on the turbine shaft at the "as balanced" angular position when reassembling the turbo center section.
In addition, to remove and replace the compressor impeller on the turbine shaft, you must heat up the impeller to between 250 and 300 degrees F, by using a hot air gun ONLY. Do not use a propane torch! (If used to heat the impeller, the part will be ruined, and cannot be reused.) Also, the correct tightening torque/method of the impeller nut is critical.
BTW, the turbo rotating assembly attains speeds exceeding 150,000 r/min occasionally. If there is any defect of the dynamic balance for that rotating assembly, the resulting unbalanced forces generated within the turbo, will wreck the unit in short order.

JeffAhn

You think there's an overspeed Op involved before and after balance for a rebuild?

diagnosticator1

Thanks!

JeffAhn

when newly mfg'd, I would imagine it goes thru an overspeed Op due to the possiblity it will grow and also to see the durability at speeds in excess of normal use conditions.

My question, for a rebuild, is that same overspeed op necessary, seeing as that the material has already gone thru this.

diagnosticator1

The dynamic balance needs to be reestablished during the rebuild, as there is always some material ablation (loss) from the impeller from dust particles ingested in the intake airstream for the time period in use since new.
The typical (but not preferred, IMO) method to clean the impeller at rebuild, via glass bead media blasting, effectively toughens the surface of the impeller from the "shot peaning" effect of glass bead cleaning. That process actually performs a "micro forging" treatment that relieves stresses, increases surface material density, and work hardens the impeller surface. I won't discuss the negative aspects glass bead media causes, just need to note that it has drawbacks also.