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Maintenance
Preventative Maintenance
1. Use clean fuel — kerosene, No. 1 home heating
fuel or diesel fuel. Clean or replace fuel filter every
100 hours of operation. Avoid water contaminated
fuel as it will seize up the fuel pump. De-soot coils
monthly. Use an additive if diesel is being used.
2. Check to see that the attached pressure washer
water pump is properly lubricated.
3. Follow winterizing instructions to prevent freeze
damage to pump and coils.
4. Always neutralize and flush detergent from system
after use.
5. If water is known to be high in mineral content, use
a water softener on your water system, or de-scale
as needed.
6. Do not allow acidic, caustic or abrasive fluids to be
pumped through the system.
7. Always use high grade quality cleaning products.
8. Never run attached pressure washer pump dry for
extended periods of time.
9. If machine is operated with smoky or eye burning
exhaust, coils will soot up, preventing water from
reaching maximum operating temperature. (See
section on Maintenance and Service).
10. Never allow water to be sprayed on or near the
motor or burner assembly or any electrical compo-
nent.
11. Delime coils as per instructions.
It is advisable, periodically, to visually inspect the
burner. Check air inlet to make sure it is not clogged or
blocked. Wipe off any oil spills and keep equipment
clean and dry.
The areas around the pressure washer should be kept
clean and free of combustible materials, gasoline and
other flammable vapors and liquids.
The flow of ventilating air to the burner must not be
blocked or obstructed in any manner.
Maintenance And Service
Unloader Valves
Unloader valves trap pressure in the line when a shut-
off spray gun is closed. Machines with unloader valves
are preset and tested at the factory before shipping.
Tampering with the factory settings may cause
personal injury and/or property damage and will void
the manufacturer's warranty.
Winterizing Procedure
Damage due to freezing is not covered by warranty.
Adhere to the following cold weather procedures
whenever the washer must be stored or operated
outdoors under freezing conditions.
During winter months, when temperatures drop below
32°F, protecting your machine against freezing is
necessary. Store the machine in a heated room. If this
is not possible then mix a 50/50 solution of anti-freeze/
water or windshield washer fluid with water in a 5 gallon
bucket. Place a short section of garden hose into the
bucket and connect it to the machine. Elevate the
bucket and turn the pump on to siphon the anti-freeze
through the machine. If compressed air is available, an
air fitting can be screwed into the inlet connector and by
injecting compressed air, all water will be blown out of
the system.
High Limit Hot Water Thermostat
For safety, each machine is equipped with a high limit
control switch. In the event the temperature of the water
should exceed its operating temperature, the high limit
control will turn the burner off until the water cools.
Pumps
Use only 10-40W weight non-foaming oil. Change oil
after first 50 hours of use. Thereafter, change oil every
year or at 500 hour intervals. Oil level should be
checked by using the dipstick found on the top of the
pump or by the red dot visible through the oil gauge
window. Oil should be maintained at that level.
Cleaning of Coils
In alkaline water areas, lime deposits can accumulate
rapidly inside the coil pipes. This growth is increased by
the extreme heat build up in the coil. The best preven-
tion for liming conditions is to use high quality cleaning
detergents. In areas where alkaline water is an extreme
problem, periodic use of deliming powder will remove
lime and other deposits before coil becomes plugged.
Karcher HDS 3.5/40 GE MT Operator’s Manual 9.807-942.0 - C
