Cummins/Onan — Check Turbocharger Bearing Clearance
Testing & diagnosis
From a Cummins/Onan owner's manual covering: KT38, KTA19, Kt19, KtA38, KtA50, N-855, NH-672, NH-743, NH-855, NT-855, NTA-855, NTC-270…. Check it applies to your exact model before use.
Applies to: Cummins/Onan Kt19, Cummins/Onan KTA38, Cummins/Onan KTA50
Procedure
- Remove the exhaust and intake piping from the turbocharger to expose the ends of the rotor assembly.
- Remove one capscrew from the front plate and replace it with a long capscrew; attach an indicator and register the point on the end of the rotor shaft.
- Push the shaft from end-to-end and note the total indicator reading.
- Check the radial clearance on the compressor wheel only by pushing the wheel toward the side of the bore and using a feeler gauge between the wheel vane tips and the bore.
- If end clearances exceed the limits, remove the turbocharger and replace it with a new or rebuilt unit.
- Install the exhaust and intake piping to the turbocharger.
Tools required
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- T-50, ST-50 FridayParts $387.36, VT-50 FridayParts $463.24 end clearance 0.006 to 0.018 inch [0.15 to 0.46 mm]
- T-50, ST-50 FridayParts $387.36, VT-50 FridayParts $463.24 radial clearance 0.003 to 0.033 inch [0.08 to 0.84 mm]
- T-18A end clearance 0.004 to 0.009 inch [0.10 to 0.23 mm]; radial clearance 0.003 to 0.007 inch [0.08 to 0.18 mm]
Full service-parts list: Cummins/Onan Kt19 →, Cummins/Onan KTA38 →, Cummins/Onan KTA50 →
Source: Cummins/Onan owner's manual. Steps and values are as documented; always cross-check against the official manual and any later revisions for your exact serial number before servicing.