4-28. ENGINE - Continued
4-28.3 Air Compressor - Continued
Compressors with a ball-type rear bearing have a seal and spring or bowed washer in the rear
Check the wear of the seal where it contacts the crankshaft. The seal must be replaced if grooved
more than 0.005 in. (0.31 mm). Measure outside diameter of seal ring. If diameter is not within
specifications, the seal ring must be replaced.
Check the oil seal spring for loads at assembled heights. Spring must conform to specifications.
Some compressors have bowed washers rather than oil seal springs. Examine bowed washer for
wear. If worn, replace.
Seal Ring Outside Diameter............ 0.633/0.632 in. (16.08/16.05 mm).
Check the crankcase as described below.
Examine crankcase for cracks and damage to gasket surfaces. Replace if necessary.
Inspect studs in crankcase. Replace any bent or damaged studs. Check all threaded holes for
damaged threads. If threads are damaged install hell-coil (thread insert).
Measure the crankcase bearing bore diameter and if not within specifications, replace the
Bearing Bore Diameters.................. 2.8350/2.8344 in. (72.009/71.993 mm)
To repair the air compressor governor refer to para. 4-22.11.
To reassemble the air compressor carry out steps m. thru v. Do not attempt to force parts into
position during assembly, as this could cause damage. Coat the crankshaft, bearings, connecting
rod bearings, pistons, pin, and cylinder block bore with engine oil (item 17, Appendix E) before
m. Crankshaft and Bearing Installation.
The crankshaft should be installed in the crankcase before rear end cap is installed. Bearings should
already be pressed on the crankshaft. Maneuver crankshaft and bearing assembly into crankcase. Be
sure that the front bearing is recessed enough to allow installation of lock ring into end of crankcase
Install lock ring used to retain the front bearing.
On compressors with rear ball bearings, place a new gasket on the cap mating surface install the spring
or bowed washer in the end cap. Outer diameter of washer must contact the bottom of the hole, in the
end cap. Install the seal in the end cap. Lubricate seal with oil install end cap making sure the seal and
spring or bowed washer does not fall out.