RING 1621964 - Caterpillar

3208 Marine Engines and 3400 Industrial, Marine Engines Equipped With Turbocharger Models 4MF, 4MFW, CMF And CMFWOver tightening of the 7N0239 Compressor Retaining Nut can result in mushrooming the shoulder of the shaft where the 4N7609 Thrust Ring seats. The over tightening can also result in a bent shaft that will damage bearings at disassembly and assembly.
The current specifications of 60 N m (44 lb ft) can be excessive, if the friction is low at the nut seating face and/or at the threads due to differences in plating or lubricants. Therefore, it is important that the tightening procedure be changed to the "torque plus turn" method which results in a much more consistent joint loading.
Follow the procedure in the Disassembly And Assembly Service Manual up to the point of installing the compressor wheel on the shaft.
Do not put side force on the shaft when tightening or removing the nut that holds the compressor wheel in position. Use a universal joint or universal drive socket when tightening.1. With the compressor wheel on the shaft, put a small amount of clean engine oil on the turbine shaft threads and the compressor wheel face that make contact with the nut.2. Install the nut, and tighten it to a torque of 14 to 17 N m (125 to 150 lb in) to push the compressor wheel on to the shaft.3. Remove the nut from the shaft. Apply 6V1541 Quick Cure Primer on the threads of the shaft and the nut.4. Put 9S3263 Retainer Compound on the threads of the shaft and the nut. Do not let the retainer compound get into the compressor wheel bore or on the shaft, because it can make removal of the compressor wheel difficult during future turbocharger disassembly.5. Install the nut, and tighten it to a torque of 4 N m (30 lb in). Then tighten the nut an additional 75° of rotation.Continue with the procedure in the Service Manual.