4-15. AUXILIARY POWER UNIT - Continued
Start engine and check for oil leaks
Repeat TEST preceding
Oil Pressure Relief Valve Repair
No repair of parts is possible. Replace components as required.
Remove plug (5).
Extract spring (7) and valve body (8).
Check valve and housing bore for scours or sticking marks. Remove any marks with emery cloth (item 13,
Measure valve diameter. Should be between 0.465 - 0.472 in. (11.80 - 11.975 mm). If less than this,
Measure spring free length. If less than 1.46 in. (37 mm), replace.
Install valve body (8) and spring (7) in engine block.
Inspect seal ring (6) on plug (5). If damaged, replace.
Install plug in engine block and tighten.
Start engine and check for oil leaks.
Repeat TEST preceding.
Oil Pump Repair
This can only be carried out with
engine removed from truck, and
engine dismounted from base.
No repair of parts is possible.
Replace components as required.
Remove APU from truck, see para. 4-15.1
Remove engine from APU base, see
para. 4-15.1 DISASSEMBLY.
Drain oil from engine by removing oil pan
Remove any burrs from crank, drive end