Karcher Karcher-Pressure-Washer-Repair-Manuals/Karcher-Pressure-Washer-Parts-and-Basic-Repair-Service-Manual-Pump-777-K1800AB-K1800IB-K1800G-K2200G-K2200IB Repair Manuals

Service Handbook

High-Pressure

Washer Pump

3.532-777.0

10.00

For Karcher Pressure Washer Parts Call 606-678-9623 or 606-561-4983

Pump 777 9/28/01 3:55 PM Page 1

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For Karcher Pressure Washer Parts Call 606-678-9623 or 606-561-4983

Pump 777 9/28/01 3:55 PM Page 2

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TROUBLESHOOTING OVERVIEW

Tools Necessary to Service the
KARCHER

®

High-Pressure Washer Pump

Part 3.532-777.0

Special Tools

•

Valve pliers . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.901-062

•

Installation tool . . . . . . . . . . . . . . . . . . . . . . . 2.901-036

(HP seal, oil seal)

•

Silicon grease . . . . . . . . . . . . . . . . . . . . . . . . 6.288-044

(for packing and O-rings)

•

Lithium grease . . . . . . . . . . . . . . . . . . . . . . . 6.288-079

(for O-rings on bypass valve)

•

Non-detergent pump oil 15W40 . . . . . . . . . .6.288-050.0

Generic Tools

•

Allen Wrench 8mm

•

Allen Wrench 6mm

•

Socket Wrench 13mm

•

Torx TX30 Socket Wrench

•

Needle Nose Pliers

•

Rubber Mallet

•

Pliers

•

Flat Head Screwdriver

•

Phillips Head Screwdriver

•

Hammer

•

Safety Goggles

How to Use This Manual

It is not necessary to read this entire manual to find a solution to
a problem. This manual identifies four basic ways the pump may
malfunction. Find the section that defines the malfunction of the
pump. Turn to that section's overview page and identify the
specific problem. Then go to the solutions page for that specific
problem. If you don't know what the problem is, work your way
through the section until you find and correct the problem.

Low Water Pressure . . . . . . . . . . . Section 1

Water Leaks . . . . . . . . . . . . . . . . . . Section 2

Oil Leaks . . . . . . . . . . . . . . . . . . . . . Section 3

Detergent Delivery Failure . . . . . Section 4

Always wear safety rated eye protection and clothing.

For any other problems contact KARCHER

®

technical support

at 1-800-877-2424.

3

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MASTER DIAGRAM

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Pump 777 9/28/01 3:55 PM Page 4

1...Pump shaft

2...Oil bath housing

5...Pump shaft ball bearing

6...Swash plate housing

8...Swash plate ball bearings

7...Nut

9...Swash disk

3...Pump shaft seal

4...Forward O-ring

10...Piston (3)

11...Piston spring

12...Piston housing

24...Low-pressure valve seat (3)

25...Low-pressure valve plate (3)

13...Weep holes (3)

23...Connection piece (2)

26...Low-pressure valve spring (3)

27...Low-pressure valve basket (3)

28...Oil seal (3)

30...High pressure seal (3)

31...Nozzle insert

14...Fastening cap

15...Deflector cap

16...Screw (2)

17...Thermal relief
valve housing

18...Thermal relief valve

19...Spring

20...Bypass valve

29...Bushing (3)

21...Water inlet

22...Water
inlet filter

34...Retainer clip

35...Nipple

36...Detergent non-return
check valve

37...Ball bearing

38...Spring

39...Detergent tube

40...Detergent filter with
metering valve

41...High-pressure valve plug (3)

42...High-pressure valve cage (3)

43...High-pressure valve spring (3)

44...High-pressure valve cap (3)

45...High-pressure valve seat (3)

46...Pump head

31...non-return check valve

33...Water outlet

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47...Pump head bolt (4)

KARCHER OVERVIEW

Bypass Valve

When the trigger of the spray gun is pulled, the entire pump
capacity flows through the nozzle insert (30) to the water outlet
(32). At this time, the bypass valve remains in the upper position
and closes off the path between the pressure chamber and the
suction chamber.

When the trigger of the spray gun is released, water ceases to
flow through the nozzle insert (32). The pressure above the by­pass valve (20) rises, which causes the bypass valve to be
pressed downwards. This will cause the pump to run in the
bypass mode. The pump continues to run, but only maintains the
circulation pressure.

When the trigger of the spray gun is again pulled, the pressure in
the high-pressure hose drops suddenly. The spring inside the
bypass valve (20), together with the restricted pressure at the
entrance to the nozzle insert (30), pushes the bypass valve
upwards. This causes the bypass valve to close, and the pump
builds up pressure once more.

Thermal Relief Valve

If the pump should continue to run in bypass mode for an extend­ed amount of time (max 5 min.), the water circulating within the
pump will reach a temperature level that will cause internal
damage. This is prevented by the thermal relief valve (18). The
thermal relief valve will release the hot water and then automati­cally reset itself.

Detergent Delivery System

In this system there is a nozzle insert (30) in the water outlet (32). The
entire pump capacity flows through the nozzle insert to the spray gun.

Detergent can only be drawn in by the nozzle insert (30) if the
nozzle of the spray wand has been set to low pressure. This
causes the pump pressure to fall to approximately 435 PSI (low
pressure), and the greatest degree of negative pressure (11.6
PSI) is generated at the lateral hole in the nozzle insert so that
detergent can be drawn into the unit via the detergent suction
tube (38) and detergent filter (39).

If the spray nozzle on the spray wand is set for high-pressure
operation, the hole in the nozzle insert (30) does not create any
negative pressure, and no detergent can be drawn into the unit.

The detergent non-return valve (34) consists of a small spring (37)
with a ball (36), O-ring (35) and nipple (34). When operating in the
detergent mode, the negative pressure created by the nozzle
insert (30) causes the ball to be drawn away from the O-ring (35),
against the tension of the spring (37). Detergent can then be
drawn into the unit.

When operating in the high-pressure mode, the ball (36) seals off
the detergent connection so that no water can flow into the con­tainer of detergent.

Swash Plate Assembly

The three pistons (10) are driven by the swash plate assembly
(6,7,8,9), which is mounted on a pump shaft (3). In the case of a ver­tically configured machine, a drive bolt is screwed into the engine
shaft and then inserted into the pump shaft. As soon as the engine
shaft rotates, the swash plate assembly ( 6,7,8,9) rotates as well.
This causes the pistons (10) to move backwards and forwards. The
piston stroke depends upon the angle of the swash plate assembly
( 6,7,8,9). The greater the angle of the swash plate, the longer the
piston stroke. One revolution of the swash plate gives the pistons
one suction stroke and one pressure stroke.

Oil Bath

The swash plate and pistons are bathed in oil
(oil type 15W40 non-detergent).

This pump does not have a drain plug, oil reservoir and sight glass.
In order to add oil in this case, the pump head (45) and piston hous­ing (12) will have to be removed. If servicing a pump without a sight
glass, the oil level is just above the high side of the swash disk (9).

Pistons With Seals

The three pistons (10) are pressed against the swash disk (9) of the
swash plate assembly (6,7,8,9) by powerful piston springs (11). These
three pistons are manufactured from tempered, surface-hardened
steel and are non-corrosive with regards to detergents and rust.

The pump delivery capacity is determined by

- the rotational speed of the motor

- the diameter of the pistons

- the length of the piston stroke.

The pistons (10) are fitted with a high-pressure bushing seal (29).

The three pistons each have a low-pressure oil seal (28) mounted
in the piston housing (12). These three low-pressure oil seals, along
with the shaft seal (3), retain the oil in the oil bath housing. The slot
holes (13) are in the piston housing (12) and allow water or oil to
drip out into the open.

A water leakage rate of one drop per piston per minute is allowable
during high-pressure operation. If oil is leaking from the slot holes

(13), there is either a leak in the oil seals or there is piston damage.

Low-Pressure and
High-Pressure Check Valves

Each piston (10) works with one low-pressure check valve (24-27)
and one high-pressure check valve (41-44). Each of these check
valves is constructed of the same basic components: the valve
basket, spring, valve plate with guide shaft and the valve seat
with O-ring.

The sealing surface between the valve plate (25) and the valve seat
(24) is conical. The valve plate and valve seat are manufactured
from either plastic or stainless steel depending upon the particular
unit involved.

When the piston (10) is forced backwards by the piston spring (11)
in the oil bath housing (2), the high-pressure check valve (41-44)
closes and water is drawn in through the supply line / suction
chamber at the water inlet (21), through the inlet filter (22), and
through the open low-pressure check valve (24-27).

When the piston (10) is pushed forward by the swash disk (9), the
low-pressure check valve closes and water is conveyed through
the open high-pressure check valve to the high-pressure outlet.
The pressure that is generated is dependent upon the flow rate and
the orifice diameter of the of the high-pressure nozzle.

5

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