OPERATOR AR 2020025 - Caterpillar

And 3512 Industrial, Marine, And Generator Set EnginesThe 3508 and 3512 Engines shown in the Serial Number Chart are equipped with water pumps which have retaining compound on the taper between the shaft and impeller. This will make removal of the impeller from the shaft especially difficult during pump disassembly. When it becomes necessary to disassemble one of these pumps, the recommendation is to heat the shaft during the application of force with the puller tool. The amount of heat needed to loosen the retaining compound will be variable, according to the grip it has on the parts. Several factors have an effect on the grip, including the fit of the taper, the surface of the metal, and the humidity (water vapor) in the air at the time of assembly.
After the impeller has been removed from the shaft, thoroughly clean the tapers on the shaft and in the impeller to completely remove the retaining compound. If necessary, a strong caustic solution can be used (like Oakite 156 or 157). Be sure to follow the manufacturer's instructions for use of these solutions.
Before installation of the impeller on the shaft, thoroughly clean the tapers with a solvent and permit them to become completely dry. Then follow the procedure in the Service Manual for assembly. Do not use retaining compound during installation of the impeller on the shaft.
The instructions to "thoroughly clean the tapers with a solvent and permit them to become completely dry" are not shown in the Service Manual procedure. Make a note of this information in your Service Manual.