Field diagnosis
Repair kit or new unit? How workshops decide
The decision follows measurable evidence, not the age of the machine. Work through these six points and the answer is usually obvious.
Check these in order
| Check | What it looks like | What it tells you |
|---|---|---|
| Where the wear actually is | Wear in the rotary group alone can often be restored with a kit; damage to the housing or shaft ends the discussion. | Strip and inspect the valve plate, cylinder block and housing bore. |
| Pressure and drain limits | A pump that cannot reach its specified pressure at the required flow will not be saved by seals alone. | Use the case drain test and a pressure test under load as evidence. |
| Cleanliness of the circuit | Fitting a repaired unit into a dirty circuit simply repeats the failure. | Flush, change filters and sample the oil before start-up. |
| Downtime versus a spare on the shelf | Where the machine is critical, keeping a matching unit on site changes the calculation. | Match the nameplate and keep a unit or kit for the fleet's common model. |
| Availability of the same variant | Regulator and shaft variants decide whether a unit bolts on and controls correctly. | Confirm the control suffix and shaft before ordering. |
| Record keeping | Deciding twice on the same unit without records usually costs more the second time. | Keep case drain and pressure numbers before and after every repair. |
Units and parts this usually leads to
Case drain flow test
The measurement that settles the argument.
Selection guides
Choosing between neighbouring models.
Datasheets
Catalogue figures to compare before ordering.
Field notes on this complaint
The notes our own team works to on this symptom. Each one is a principle you can check on the machine, a step from the case-drain and cleanliness procedure we follow, or a figure transcribed from our catalogue - not advice copied from a video or a forum. Anything we could not check against a catalogue, a manufacturer document or a working machine is left out.
- The case-drain figure decides. Measure case-drain flow at working temperature. A worn piston and slipper pair is a repair-kit job more often than a whole-unit job. (our own case-drain and cleanliness procedure)
- No clearances or torques without the document. We publish a torque or clearance figure only when we have the manufacturer document in front of us. Ask for your exact unit and we check the figure we hold. (our publication rule)
- On a K3V / K5V, the flow setting lives in two adjusters - do not touch them to clean The Kawasaki service manual for the K3V / K5V range carries a warning worth printing: do not loosen the hexagon stroke adjustment nuts on the valve block or the swash plate support, because the pump flow setting will be changed. Those two adjusters are the pump's calibration, not a fastener to be loosened during cleaning, and once moved the unit has to be re-set on a test bench. If a repair shop proposes opening that part of the pump for a dirt problem, ask what they will use to re-set the flow afterwards. (manufacturer service or operator manual we hold (title on request))
- Two workshop rules from the Kawasaki manual: work clean, and never hammer the shaft The K3V / K5V repair manual gives the practical rules for opening and reassembling these pumps: remove dust and rust from the surfaces first, drain the case through the drain port plug before taking it apart, do not remove the needle bearing unless it definitely needs replacing, and do not tap the drive shaft with a hammer - press or tap the outer race of the bearing lightly. The manual also notes that Loctite is applied in production to the tilting pin and servo piston, so those areas need care. A pump that comes back with a bent shaft or a marked swash plate was usually reassembled against one of these rules. (manufacturer service or operator manual we hold (title on request))
Common questions
How long should a repaired pump last?
That depends on the wear left in the housing, the cleanliness of the circuit and the duty cycle. Measure case drain flow after the repair - that is your baseline for the next decision.
Can every pump be rebuilt?
No. If the housing, shaft or valve face is beyond tolerance, a rebuild is a temporary fix. Strip and measure before committing.
Do you supply complete units and internal parts?
Both. Catalogue part lines cover seals, valve plates, cylinder assemblies and regulator parts, and complete pumps and motors are supplied as units. Send the nameplate photo for confirmation.
Why it happens
The mechanism behind this symptom, from our technical articles: reading the principle first usually shortens the checklist.
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