TM 5-3820-246-14&P
Malfunction
Test or Inspection
Corrective Action
ENGINE STARTS BUT DOES NOT REACH NORMAL RUNNING SPEED.
1.
Disassemble engine cylinder
5-7) and check for damaged or excessive wear of hammer piston rings or
5-8).
engine piston rings
Replace damaged, worn, or broken engine piston rings
5-7) or hammer piston rings
5-8).
SUDDEN INCREASE IN ENGINE SPEED.
2.
Step 1.
Check tool shank length and width. Verify shank is straight.
Replace tool if improper dimensions.
Step 2.
Remove hammer piston
5-8). Check if the head is reddish purple. If it is, check for
distortion of the piston by using a straight edge.
Replace the hammer piston and rings if distorted.
3.
ENGINE RUNS NORMALLY BUT THE DRILL ROD DOES NOT TURN.
Check if ratchet mechanism is damaged. Damage has occurred if ratchet can be easily turned CCW.
Remove front end assembly
4-22).
Replace trigger spring if damaged
5-11).
Replace triggers if damaged
5-11).
Replace ratchet gear if damaged
5-11).
4.
ENGINE RUNS NORMALLY BUT TOOL ACTION IS WEAK.
Step 1.
Remove hammer piston and check if damaged or worn
5-8).
Replace hammer piston and rings if damaged, worn, or distorted
5-8).
Step 2.
If tool can be turned easily CCW check for defective ratchet wheel, internal shaft, or hammer
piston.
If wear on straight and lead splines of the ratchet wheel, internal shaft, or hammer piston
exceed 0.04 in. (1.0 mm) replace the defective part
5-l 1) or
5-8).
If wear on the hexagonal bore of the internal shaft exceeds 0.92 in. (23.3 mm) across the
flats replace hammer piston
5-8).
5-3
