How often should the turbo be rebuilt with new orings and bearings as preventative maintenance? I have a Powermax with unknown miles. Was cleaned roughly 30K miles ago but I'm thinking of a KC Turbos rebuild kit.

 

If it's clean the only thing I would do is get a dial indicator and
check the shaft to see how much up and down moment there is.
The next check is inand out movement. Is this a Ford assembly
or an aftermarket assembly? Then I can look up the needed info.

 

It's a Powermax

 

I think as a rule of thumb, the Garret specs would apply unless I'm missing something......it's still a Garret turbo

The Ford workshop manual specs. for acceptable turbo shaft endplay and radial play is 0.091 mm (0.0036 in) for the endplay, and 0.5 mm (0.02 in) for radial play. If either one of those dimensions are exceeded with your inspection, you'll need to replace the turbo or the center housing rotating assembly anyways, depending on the condition of the turbo vanes and the unison ring.

Use a dial indicator as Sean mentioned.
I did on the last one I pulled off, even though it was quite plainly shot.

 

Mike,Thanks for posting that data.
I am still a bit under the weather.

 

Hey Sean, hope you feel better.

If there is a hint of radial play, it's time to dig deeper into the turbo to see if it's salvageable. End play is commonly noticeable, but if you can see impeller scrapes on the intake housing, it's time to do something about it. There should be no rubbing seen or felt on the intake side of the housing if you spin the shaft with your fingers. If you force with your fingers "radial play" to try to get it to rub, you may feel the impeller "touch" at a very minimal level, the intake side of the housing. However once oil pressure is present, the shaft, (as long as it is within specs) won't rub.
Usually the only time you mess with the turbo, (other than catastrophic) is when there is a noticeable and significant problem mainly to do with a failed exhaust turbo seal causing it to leak then smoke out the turbine side. If it's a bearing issue, then most likely already have unrepairable tolerance issues that will point to replacement of the whole unit unless you have access to a turbo graveyard of parts.
However, these turbos are easy to repair if it's just a pitting issue, a seal, or busted unison ring .

 

 

Sure there's a reason, parts are only 10% of the cost of a new turbo.
There is no reason to rebuild a turbo on a "maintenance" routine, only if failed.