Model: WP6
Part Number: 12159765
Brands: Weichai Power
Engine Model: WP6, WP6G, WP6H
Engine Type: Diesel
Scope of application: light and medium trucks, buses, agricultural machinery, generator sets
Oil pressure is the engine's first line of defence. Part 12159765 is the gear-type oil pump for the Weichai WP6, drawing oil from the sump, pressurising it and pushing it through the filter, main galleries, crankshaft and up to the cylinder head. On this family the pump also supplies the piston cooling jets, so flow matters as much as pressure.
When the pump wears, the symptom is rarely a sudden warning light. Pressure falls slowly at hot idle, oil temperature rises and bearing wear begins long before the driver notices anything unusual.
The pump fits WP6, WP6G and WP6H engines in light and medium trucks, buses, tractors and small generator sets. Confirm the engine plate and the old pump number before ordering. Industrial variants can use a different pick-up arrangement even when the pump body looks identical, and a mismatched pick-up starves the pump at high load.
Every pump is run on a test bench rather than only inspected. Flow is measured at rated speed against the original curve, the relief valve is opened and its pressure recorded, gear backlash and end clearance are measured, and the housing and joints are leak tested.
Pumps ship oiled and plugged, with the drive gear fitted and keyed as original.
Low oil pressure is the headline symptom, but the details matter. Pressure that is low only when hot points to worn bearings as much as a worn pump. Pressure that recovers instantly with engine speed points to the relief valve or pump clearances.
Confirm with a mechanical gauge at the main gallery. A blocked strainer imitates a worn pump exactly.
Check oil level and condition, replace the filter, inspect the strainer, then measure pressure with a mechanical gauge. Only after those steps should the relief valve and the pump come under suspicion. Recording cold idle, hot idle and rated speed gives a clear diagnosis and avoids buying parts that are not needed.
Match the part number, the engine rating and the drive type. If the engine has been rebuilt with a replacement front cover, check that the mounting face and drive gear match. Send a photo of the old pump beside a ruler and we will confirm the casting before shipping.
On these engines the pump also supplies the piston cooling jets. A pump that delivers pressure but not enough volume still allows crown temperatures to climb, and the damage appears as a scored or cracked piston rather than low oil pressure. If pistons have failed without an obvious cause, measure flow before blaming the pistons.
Fitting a pump without testing the rest of the system wastes the part. After assembly, measure pressure at three points: cold idle, hot idle and rated speed, then compare with specification. A pump that holds rated pressure but drops at hot idle usually has worn bearings downstream. Also check the filter bypass and the oil cooler for restriction.
Most premature failures come from contaminated oil. Use the specified grade, change it at the severe-duty interval and never run with a leaking injector that thins the oil with diesel. Keep the cooling system healthy too, because sustained overheating reduces oil film strength at the bearings.
Yes, the mounting gasket and O-ring are supplied.
Yes. A blocked strainer, stuck relief valve, worn bearings or a faulty sender all mimic pump failure.
The pump comes with its drive gear fitted and timed as original.
At every major overhaul, or whenever the front cover is removed.
Browse the Weichai pump category, and pair the pump with the WP6 crankshaft 13031181 or the WP6 engine overhaul kit 13032095.
Weichai WP6 Oil Pump (12159765). The oil pump moves a fixed volume per revolution. Pressure is created by the resistance that volume meets in the galleries and bearings, not by the pump alone.
Compare the old pump number and photograph the drive end. A pump with the wrong drive bolts up and fails to feed correctly.
Numbers beginning 1215 are used across the WP6 series. Two parts can share the first four digits and differ in the drive or mounting detail. On this engine, confirm the WP6 application against the engine plate before ordering.
Prime the pump before the first start and confirm oil pressure at the gauge before allowing the engine to run. Never crank a fresh rebuild hoping pressure will arrive.
Ordering note. Photographs of the actual unit can be sent before dispatch on request. That is the cheapest way to avoid a return when a casting revision is in doubt.
Related reading: Oil Pump Diagnosis: Low Pressure, Wear and Replacement
| We Are 30 Years Diesel Engine Parts Supplier | |
| Brand | EPID |
| Warranty | 12 Months |
| Condition | 100%New |
| More Models | Weichai: WP6, WP6G, WP6H, and other Weichai series. |
| Shipping | By sea / air / express (DHL, FEDEX, TNT, UPS, EMS) |
| Packing | Standard exporting packing or as required |
| Payment Term | L/C, T/T, Western Union, Trade Assurance |
| Delivery Time | 3-7 days (depend on order) |
| Selling Point | 1. On-time Delivery 2. Genuine Quality Assurance 3. Professional Supplier |
Every pump is run on a test bench rather than only inspected. Flow is measured at rated speed against the original curve, the relief valve is opened and its pressure recorded, gear backlash and end clearance are measured, and the housing and joints are leak tested.
Pumps ship oiled and plugged, with the drive gear fitted and keyed as original.
Low oil pressure is the headline symptom, but the details matter. Pressure that is low only when hot points to worn bearings as much as a worn pump. Pressure that recovers instantly with engine speed points to the relief valve or pump clearances.
Confirm with a mechanical gauge at the main gallery. A blocked strainer imitates a worn pump exactly.
Check oil level and condition, replace the filter, inspect the strainer, then measure pressure with a mechanical gauge. Only after those steps should the relief valve and the pump come under suspicion. Recording cold idle, hot idle and rated speed gives a clear diagnosis and avoids buying parts that are not needed.
Match the part number, the engine rating and the drive type. If the engine has been rebuilt with a replacement front cover, check that the mounting face and drive gear match. Send a photo of the old pump beside a ruler and we will confirm the casting before shipping.
On these engines the pump also supplies the piston cooling jets. A pump that delivers pressure but not enough volume still allows crown temperatures to climb, and the damage appears as a scored or cracked piston rather than low oil pressure. If pistons have failed without an obvious cause, measure flow before blaming the pistons.
Fitting a pump without testing the rest of the system wastes the part. After assembly, measure pressure at three points: cold idle, hot idle and rated speed, then compare with specification. A pump that holds rated pressure but drops at hot idle usually has worn bearings downstream. Also check the filter bypass and the oil cooler for restriction.
Most premature failures come from contaminated oil. Use the specified grade, change it at the severe-duty interval and never run with a leaking injector that thins the oil with diesel. Keep the cooling system healthy too, because sustained overheating reduces oil film strength at the bearings.
Browse the Weichai pump category, and pair the pump with the WP6 crankshaft 13031181 or the WP6 engine overhaul kit 13032095.
Yes, the mounting gasket and O-ring are supplied.
Yes. A blocked strainer, stuck relief valve, worn bearings or a faulty sender all mimic pump failure.
The pump comes with its drive gear fitted and timed as original.
At every major overhaul, or whenever the front cover is removed.
EPID supplies diesel engine parts for Weichai, Baudouin, Yuchai, Caterpillar, Sinotruk, FAW Xichai and Cummins engines. Every order is checked against the original part number before packing, and our team can identify a part from a photo of the engine plate. Ask for a quotation with your model and quantity and we will reply within one working day.
