83 CDT Garrett turbo

I overhauled the turbo using the mercedessource kit.
Had the turbo and compressor balanced.
Need advice on turbo compressor nut torque techniques.
I used the kit recommendation:
Nut touch the compression wheel, turn CW about 90 degrees using supplied 3/8 wrench and stopped when I judged force to be adequate. Balance marks aligned.
Turbo whine is noticeable when cold engine. Much less so when operating engine temp.
I judge to be a nut torque issue.
I noted that the wrench turn is nearly 80 degrees from initial touch position to set the compressor turbine. Wrench turn is easy.
During the next 10 degrees drag increases rapidly.
Any ideas as to torque techniques?

Forums

Diesel Engine Specific Aid

Chassis Model Number

W123

I doubt torque is the issue

You may always hear some whine after rebuilding an old turbo due to increase impeller speed (especially if there was a lot of carbon buildup). Did you check boost pressure at the manifold? If the whine is extreme I doubt that the torque of the shaft nut is the cause. It would have to be loose and wobly. I suspect the problem is elsewhere - ie balance, shaft wear, worn impellers, etc.

Torque is an Issue

126k miles would suggest a turbo not worn excessively. The shaft bearing surfaces had minimal wear. Performance is much improved below 2000 rpm. Whine isn't extreme but noticeable and decreases with an increase in engine temp. I was told by a turbo tech that too much torque can induce whine. How much torque is a matter of opinion. Your instructions are clear. Touch and then 80 - 90 degrees turn but no extension to the supplied 3/8 inch wrench. Others say 90 degrees after 20 inch lbs torque. Would require an extension this turbo and lots of torque. Turbo shaft and compressor were balanced individually and together. Should be balanced torque to marks.

The Torque Solution

1. Compressor nut torque problem was solved by installing a new Thrust Spring.
2. The turbo whine was solved by rotating the compressor wheel balance mark 180 degrees to the shaft/turbo mark.

1. Before, the compressor nut would have no resistance for 70 degrees of turn then resistance increased rapidly. After install of the new Spring, smoothly increasing resistance to the 80 degree point where I judged adequate. All kits should have a new Thrust Spring.
2. An inquiry to a turbo shop resulted in the 180 degree recommendation. Must listen to hear the turbo in the sensitive RPM and load range.