JET
11
Troubleshooting JCT-4660 series Paving Breakers
Any disassembly of the tool should be done by qualified service personnel. For problems not addressed
below, contact JET technical service at 800-274-6846.
Problem
Possible cause
Remedy
Tool will not start.
Air valve closed or obstructed.
Open valve; clear any obstructions.
Dirt or gum deposits on
components.
Flush tool with gum solvent.
If problem persists, disassemble,
clean and lubricate internal parts.
Throttle lever malfunction.
Clean throttle lever mechanism to
ensure free movement. Replace
mechanism if needed.
Piston seized due to improper
lubrication.
Lubricate breaker according to
instructions.
Starts immediately as soon
as air is connected without
lever being pressed.
Throttle valve malfunction.
Inspect and repair throttle valve.
Excessive or abnormal
vibration.
Improper lubrication.
Lubricate properly according to
instructions in this manual.
Loss of power; erratic
action.
Low air pressure or air volume.
Verify compressor has proper CFM
rating for tool.
Check compressor regulator
setting; set air pressure to 90 psi.
Check for loose connections at air
inlet, o-rings, etc.
Moisture or obstruction in air
hose.
Air supply must be clean and dry.
Clean out air hose(s) and remove
any kinks or bends.
Improper size of air transmission
lines, hoses, fittings, or
couplings. Or, air supply line too
long.
Use appropriate-sized air lines/
hoses. Verify proper fittings,
couplings. Use shorter supply line if
needed.
Dirt or gum deposits on
components.
Flush tool with gum solvent.
Check and clean air filter on
compressor.
Clean external areas of tool. If
problem persists, disassemble,
clean and lubricate internal parts.
Front head bushing excessively
worn.
Replace front head bushing.
Loose bolts in front or back head.
Tighten bolts.
Loss of impact, or loss of blows
per minute.
Check clearance between piston
and cylinder. Maximum clearance
should be 0.005 in. (0.13mm).
Check that piston moves freely and
is not seized.
Throttle valve seizing.
Inspect; clean or replace elements.
