Hitachi 4043 Pump Service, Servicing the Valves, Servicing the Pumping Section, Disassembly

Pump Service

Servicing the Valves

1.Remove the hex valve plug.

2.Examine the o–ring under the plug for cuts or distortion and replace if worn. Lubricate new o–ring before installing.

3.Grasp valve retainer by tab at the top with pliers and remove from valve chamber. Valve parts usually separate during removal.

Note: A special tool will be needed to remove the seat from the manifold. A reverse pliers or a standard vise grip and a 1/4” x 3” bolt to fit I.D. of seat inserted under the edge of the seat, will pry the valve seat out easily.

4.Examine all valve parts for wear and replace with preassembled valve assembly in service kit containing retainer, spring, valve, valve seat, o–ring, and back–up ring.

5.Grasp new valve assembly by tab at top with pliers, immerse in oil and push into valve chamber. Be certain valve assembly is square in valve chamber.

6.Apply Loctite 242 to valve plug, thread into manifold port and torque per chart.

Note: Corrosion Resistant models require the coil spring installed in the Valve Plug.

Servicing the Pumping Section

Disassembly:

1.Remove the four (4) hex nuts or two (2) bolts from the manifold (varies with model).

2.Rotate crankshaft by hand to start separation of manifold from crankcase. Support the underside of the manifold and tap lightly with a mallet to remove the manifold assembly.

CAUTION

Keep manifold properly aligned with ceramic plungers when removing to avoid damage to either plungers or seals.

3.Remove oil pan and slide out seal retainer with wicks.

4.Using a wrench, loosen the plunger retainer. Grasp ceramic plunger and push toward crankcase until plunger retainer pops out.

5.Remove plunger retainer with copper gasket, back–up Ring and o–ring.

6.Remove plunger from plunger rod.

Reassembly:

1.Carefully examine each ceramic plunger for scoring or cracks, replace if worn and slip onto plunger rod.

Note: Ceramic plunger can only be installed one direction (front to back). Do not force onto rod.

2.Examine plunger retainer and stud and replace if worn.

Note: Thread stud into plunger retainer.

3.Examine o–ring, back–up ring and gasket on plunger retainer and replace if worn or cut. Lubricate o–ring for ease of installation and to avoid damaging o–rings.

Note: First install gasket, then back–up ring and o–ring.

4.Thread plunger retainer and stud assembly into plunger rod. Exercise caution not to over torque.

5.Saturate new oil wick by soaking in oil, place in seal retainer and slip retainer over ceramic plunger.

6.Replace oil pan.

7.Turn shaft by hand to line up plungers so end plungers are parallel.

8.Carefully slip manifold onto plungers, keeping manifold level, and tap with mallet to bring manifold flush with crankcase.

9.Replace washers and nuts or bolts and torque per chart.

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