3.3 Details

Withdraw the rotor from the hydraulic head. Examine the running surface very closely for signs of erosion, particularly the area around the delivery port. If severe erosion is evident, the head and rotor assembly must be replaced.

If damage to the plungers is suspected, carefully separate the plungers from the rotor, one at a time, and inspect them for scoring or other damage. Clean each plunger with test oil and immediately replace it very carefully in its original bore, the same way round.

The recommended plastic retainer or short lengths of clean nitrile rubber tubing should be used to retain the plungers in their bores. Replace the hydraulic head if the plungers show severe scratching.

Inspect the running surface of the cam ring and scroll plates for signs of breakdown of the leading face or apex of the profile. If there are significant signs of pitting or "smearing" they must be replaced as a set. Smearing is the result of failure of the surface due to abrasion or overloading, which may be due to excessive hydraulic pressure (possibly caused by nozzle blockage).

Inspect rollers and shoes for damage. Pay particular attention to the condition of the contact surfaces and check that the rollers rotate freely in their shoes. If the cam ring has failed, the rollers and shoes may also have been severely damaged. If satisfactory, rollers must be replaced in their original shoes.

Check blades for chips, scores or breakages. Blades may be of carbon, resin-bonded carbon, or sintered steel. Resin-bonded blades have an identification groove in the base of the central slot. Carbon blades have no groove.

Blades must be replaced in sets and must be of the same type as the originals. Examine the transfer pump rotor for wear or damage.

Examine the inner face of the end plate for wear. Replace it if there is any significant scoring. If a separate sandwich plate is fitted. and it is scored or worn, it must be replaced and not reversed.

Examine the liner for corrosion or scoring and replace it if there are any signs of damage.

Check all control valves for wear or scoring. Examine the metering valve for "stepping" of the control slot edges and at the point where it enters the bore in the hydraulic head. Check that the valve and the governor link pin are securely fixed in the bar. Check the regulating valve, latch valve and rotor vent switch valve for damage or corrosion and blockage of orifices.

Check for defects in delivery valve assemblies. If movement of the valve can be detected when shaken, the spring may have collapsed, in which case it should be replaced. lnspect the cambox pressurising valve (if fitted) for wear and damage, particularly the spring, valve and filter spring.

Look for distorted or fractured springs. Very carefully examine the areas of contact with adjoining components (spring pegs, throttle shaft links etc).

Check that all springs specified in the Parts List for the pump are present.

Check all screws and nuts for damage. Check the cam advance screw flats, which may have been damaged by careless application of the high tightening torque.

Check all threads for damage, especially on the transfer and distributor rotors, hydraulic head, cam advance screw hole, studs, fuel inlet and return and high pressure outlet connections.

lnspect all mechanical governor linkages, shafts, pivot pins and arms for wear, cracks or scoring of their mating surfaces.

Examine the cold idle advance spring-loaded plastic link for breakage.

Examine control shafts and their associated bores in the governor cover for distortion, wear, looseness of joints or elongation of spring anchor holes. The items in this group are; the excess fuel shaft, idling and manual idling advance shafts, speed control, manual stop, and their associated levers and linkages.

lnspect the shaft for wear or damage, especially where the oil seal(s) contacts the shaft. Check splines and keyways for cracks or chipping.

Examine the thrust surfaces on the inner face of the pump housing and the weight cage for damage or scoring.

Examine the governor weight cage and weights for wear, cracks, or damage. Ensure that the correct number and

type of governor weights are fitted.

Examine the components for corrosion. If water has been present in the fuel, it will tend to settle in the advance

housing.

Check that pistons move freely.

Examine all levers for excessive wear at contact points and for cracks.

Examine the HSDI light load advance cam for excessive wear.

Examine the housing for damage, especially to the sealing surfaces. II the bearing is unfit for further service, the

housing must be replaced.

Examine all orifices for blockage and carefully clear any obstruction with dry compressed air.

Ensure that all electrical solenoid parts are clean, especially the connection(s), and that the plunger is free in its

bore. Check that the flexible valve seat is in good condition, with no pitting or other damage.

if any fault is apparent in the stop solenoid assembly, the whole unit must be replaced as the plunger is matched to the body.

Some DPS pumps are fitted with hydraulic heads having an oversize metering valve bore and an oversize metering valve to suit. Pumps fitted with such heads have the number 6.375 etched between the outlet connections adjacent to the metering valve bore. The appropriate metering valve part number is given in the Parts List, as "Size B':