Published 2026-09-14 · Weichai engine parts · EPID
The water pump drives coolant through the block and radiator; the oil pump maintains the pressure that keeps the bearings alive. This guide explains how to tell when Weichai water pumps and oil pumps need replacing, how to verify fitment before ordering, and what the quality grades actually mean.
What water pumps and oil pumps do in a Weichai engine
The water pump drives coolant through the block and radiator; the oil pump maintains the pressure that keeps the bearings alive. On Weichai engines (WD10, WD12, WD615, WD618, WP10, WP12) these parts are shared across several ratings, so the OEM number - not the model name alone - is what identifies the correct item.
Signs they need replacing
- Overheating at low engine speed
- Coolant leaking from the weep hole
- Oil pressure falling as the engine warms
- Whining or bearing noise from the pump
One symptom rarely justifies a replacement on its own. Two or three together - for example oil consumption plus blow-by plus smoke - almost always do.
How to verify fitment before you order
- Read the OEM number off the old part rather than from a catalogue drawing.
- Give the engine serial number. Weichai builds the same nominal model in more than one configuration.
- Check impeller clearance and shaft play on the water pump, and pressure-test the oil pump relief valve before condemning it.
- Confirm the sizes. If a crankshaft has been ground or a block decked, standard parts may no longer fit.
Genuine, OEM-grade or aftermarket?
| Grade | What it means | Typical use |
|---|---|---|
| Genuine | Supplied in Weichai packaging with the original part number | Warranty work, customers who specify OEM only |
| OEM-grade | Made to the original specification and tolerances, often by the same tier of factory, without the brand packaging | Most fleet and rebuilder work |
| Aftermarket | Independent manufacture to a compatible specification | Older engines, cost-sensitive jobs, non-critical positions |
We quote the grade per line so you can mix: genuine valves with aftermarket gaskets, for example, is a common and sensible combination.
What drives the price
- Engine size and the number of cylinders - a 6-cylinder kit costs more than a 4-cylinder kit
- Quality grade and whether the part is genuine
- Quantity - container orders get factory-direct pricing
- Included components: a liner kit with pistons, rings and pins is not comparable to a bare liner
Installation and break-in notes
- Clean the bore or seating surface and check it for damage before fitting
- Lubricate sealing surfaces with the recommended assembly lubricant, not grease
- Torque in the specified sequence and stages - bolted joints on diesel engines are torque-to-yield on many models
- After a rebuild, run at moderate load and re-torque or re-check as the manual requires
Weichai Water Pumps and Oil Pumps we supply
| Part number | Part | Model | |
|---|---|---|---|
| AZ1500070021A | Weichai Oil Pump WD615E2 AZ1500070021A | water pumps and oil pumps | Details |
| 1000550425 | Weichai WD10 Oil Pump 1000550425 | WD10 | Details |
| 10044321342 | Weichai WD10 Oil Pump 10044321342 | WD10 | Details |
| 10044321372 | Weichai WD10 Oil Pump 10044321372 | WD10 | Details |
| 1500070021 | Weichai WD10 Oil Pump 1500070021 | WD10 | Details |
| 612600070365 | Weichai WD10 Oil Pump 612600070365 | WD10 | Details |
Full lists: Weichai part numbers - all Weichai water pumps and oil pumps.
Related pages
- Weichai engine parts
- OEM part number directory
- Overhaul kit guide
- How to cross-reference part numbers
- Weichai pistons and piston rings
- Weichai cylinder liner
- Weichai cylinder head