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WATER TRUCK TROUBLESHOOTING
PROBLEM CAUSES SOLUTIONS
SPRAY HEADS
The spray head stays on
all the time or leaks with
the engine shut off.
The valve has a broken spring,
bad diaphragm, or seal, keeping
the valve from being able to
seal.
Drain the water in the tank below the spray head. Take
the cover off the spray head and replace the bad spring,
diaphragm or seat as needed, replace the cover.
The valve has debris holding it
open.
Check the spray valves for debris, and clean debris as
needed. Check the spray bar for debris and clean as
needed.
The spray head is spurting when the spray valve is off.
The hydraulic cylinder or hoses
have air trapped in them.
Bleed the air out of the spray head cylinders and hoses.
The spray heads do not have
enough pressure supplied to the
cylinders to hold them closed.
Pressure reducing valve is set
too low.
Adjust pressure reducing valve going to the spray head
cylinders per print. 350 to 450 PSI is recommended. The
seals on the cylinders have a 500 PSI rating. Do not ex-
ceed 500 PSI.
If equipped with a diverter valve,
it uses a small ow cartridge
for control speed of the water
cannon hydraulic motors. If
pressure for the spray head
valve bank is controlled using
this ow-controlled source, the
uid ow does not hold the
valves closed, resulting in water
sputtering when other valves are
operated.
Verify diverter valve ports A8 and B8 are not used to sup-
ply pressure to the spray head manifolds. These two ports
must be used for the hydraulic water cannon to limit ow
to the motors. Change the hydraulic connection as needed
to ports C8 to E8.
A bad or missing check valve
going to upper side spray heads.
(Articulated trucks only).
Replace or add a check valve going to the spray head
manifold pressure port.
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TROUBLESHOOTING
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