SECTION 5
TROUBLESHOOTING
Jan 2001
Page 5-4
05114608
HP Check Valves Leak
If there are no visible HP water
leaks, but there are higher
temperatures on HP cylinder
or sealing head, this is an
indication of a HP or LP
check valve leak. Use
corrective action listed at
right:
1. Disconnect the proximity switch cables of the
opposite (normal) HP cylinders.
2. With the cutting nozzle valve open, start pump
at low pressure; the pistons will move and
stop at the opposite (normal) HP cylinders.
3. Stop pump, assure all pressure is bled, block
system by closing cutting valves.
4. Start pump, switch hydraulic pump to HI
pressure.
5. Assure there are no external water leaks.
6. Reconnect the proximity switch cables. The
pistons will reverse:
• If the plunger moves (the problem side
proximity switch light will turn ON), it
means inlet check valve problem.
• If the plunger does not move, it means a HP
discharge check valve problem.
Normal Temperature, but Check Valve Problem
Since the HP check valves are interconnected, to determine which of the four inlet
check valves or four discharge check valves is causing the problem, follow these
procedures.
Check inlet HP check
valve
1. Follow the procedure outlined in “HP Check
Valves Leak”.
2. A bad inlet check valve will be indicated by a
piston moving after the proximity switch
cables are reconnected.
Check discharge HP
check valve after
completing inlet check.
1. Re-install all HP plumbing and proximity
switch cables
2. Start pump, switch to HI, and then close
nozzle valve.
3. Stop pump and watch high pressure gage.
4. If the pressure drops, one of the four
discharge check valves is leaking.
5. Determine which valve is leaking by inspection.
Look for erosion or uneven wear on the poppet
or seat.
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