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- Wanda Plaza, Jinan, Shandong, China
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WEICHAI WP12 Cylinder Head Subassembly is a precision-engineered top-end component that integrates the valve train, combustion chamber roof, and cooling passages for the WP12 heavy-duty diesel platform. This subassembly includes the cast cylinder head body with installed valve guides, valve seats, and injector bores, ready for final assembly with valves, springs, and rocker gear. As a core part of the engine’s sealing and breathing system, the WEICHAI WP12 Cylinder Head Subassembly is manufactured from high-strength gray cast iron (HT250) with advanced thermal treatment. For genuine replacement parts, always choose verified WEICHAI Engine Parts to guarantee perfect fitment and durability across all WP12 variants.
The WEICHAI WP12 Cylinder Head Subassembly refers to the complete cylinder head casting that comes with factory-installed valve guides, valve seat inserts, injector sleeves, and core plugs. Unlike a fully dressed cylinder head, this subassembly does not include valves, springs, rocker arms, or the valve cover. It is designed for engine rebuilders who prefer to assemble their own valvetrain components or for partial head replacements where the valvetrain is transferred from the old unit.
Manufactured using high-grade gray cast iron with nodular graphite additives, the WEICHAI WP12 Cylinder Head Subassembly achieves a tensile strength of up to 300 MPa and Brinell hardness ranging from 190 to 240 HB. The material selection provides excellent resistance to thermal fatigue and mechanical stress caused by peak cylinder pressures exceeding 180 bar (2,600 psi). The subassembly features a cross-flow four-valve-per-cylinder layout (2 intake, 2 exhaust) with a swirl ratio of 1.8–2.2 for optimized air-fuel mixing.
Integrated Top-Down cooling passages direct coolant flow around the fire deck (the area between valve seats) and around injector nozzles, reducing the temperature of the top land by up to 30°C compared to conventional designs. Each WEICHAI WP12 Cylinder Head Subassembly undergoes 100% pressure testing at 5 bar (cold) and 200 bar (hot running simulation) to verify water jacket integrity and freedom from porosity. X-ray and ultrasonic inspections are also performed to detect internal voids.
The subassembly is compatible with both mechanical unit pumps and common rail fuel systems (Euro III, IV, V) across WP12 power outputs from 336 HP to 550 HP (247 kW to 405 kW). It supports engine applications including Shacman F3000/X3000, Sinotruk HOWO A7, Dongfeng KL heavy trucks, SDLG wheel loaders, XCMG excavators, and marine generator sets. The valve guide bores are precision-machined to 8.000 mm ±0.015 mm, and valve seat inserts are induction-hardened to 55–60 HRC.
Every genuine WEICHAI WP12 Cylinder Head Subassembly carries laser-etched part numbers and production date codes for full traceability. Counterfeit units often lack proper heat treatment and may have porosity that leads to cracking between valve seats within 50,000 km of service. Always source from authorized distributors to ensure the subassembly meets WEICHAI’s original drawings and metallurgical standards. This subassembly is offered in both bare casting and semi-finished versions (guides and seats installed but not finish-reamed) for workshops that require custom clearances.
For high-altitude operations (up to 4,100 meters) or extreme ambient temperatures (-35°C to 50°C), the WEICHAI WP12 Cylinder Head Subassembly has proven reliability through more than 45,000 hours of cumulative bench testing. The corrosion-resistant coating on water passages prevents electrolytic degradation when using modern coolants containing organic acid technology (OAT). When ordering, specify the emission level and compression ratio (standard 17.5:1 or low-compression 16:1) to match your engine variant.
| NO. | Part NO | Description |
|---|---|---|
| 1 | 612630040001 | Cylinder Head Subassembly (Bare Casting, with Guides & Seats) |
| 2 | 612630040013 | Cylinder Head Subassembly (Semi-Finished, Guides & Seats Installed) |
| 3 | 612600010593 | Cylinder Head Gasket (Steel Multilayer, 1.6mm compressed) |
| 4 | 612600030214 | Intake Valve Guide (Set of 12, Phosphor Bronze) |
| 5 | 612600030215 | Exhaust Valve Seat Insert (Set of 12, Stellite-coated) |
| 6 | 1003314752 | Cylinder Head Bolt Set (Grade 10.9, M14x2.0, 26 pcs) |
| 7 | 612600030216 | Injector Sleeve & Copper Washer Kit (6 cylinders) |
| 8 | 612700040018 | Cylinder Head Gasket (Reinforced for Euro V) |
| 9 | 612630040286 | Core Plug / Freeze Plug Set (Brass, 8 pcs) |
| 10 | 1000928221 | Cylinder Head Subassembly (with Solenoid Valve Mounting) |
The table above lists the most commonly ordered service parts for the WEICHAI WP12 Cylinder Head Subassembly. When rebuilding, always replace cylinder head bolts (Part No. 1003314752) because they stretch after initial torque cycles. Using new bolts ensures accurate clamping load distribution across all 26 bolt holes.
Our WEICHAI WP12 Cylinder Head Subassembly is cast in IATF 16949 certified facilities using the same tooling as genuine parts. Each unit is X-ray inspected for internal porosity and heat-treated to relieve residual stresses.
Valve guide bores are CNC-reamed to 8.000 mm ±0.015 mm with 0.02 mm straightness. Valve seat concentricity is held within 0.03 mm, preventing premature valve wear and ensuring leak-free sealing.
Optimized cooling jacket design reduces peak metal temperature by 15-20°C compared to generic aftermarket heads, significantly extending service intervals and preventing fire deck cracks.
No modifications required for WP12 engines in HOWO, SHACMAN, FOTON, and other Chinese heavy trucks. Bolt holes align perfectly with original dowel pins; gasket surface flatness ≤0.05 mm.
Every WEICHAI WP12 Cylinder Head Subassembly undergoes hydrostatic pressure testing at 5 bar, running leak test at 200 bar, and vacuum testing on all ports. No porosity or coolant seepage is tolerated.
We ship worldwide from warehouses near major ports. Express delivery available for urgent repairs. Bulk order discounts for fleet customers. Free torque sequence charts provided.
Unlike low-cost alternatives that use recycled cast iron with unknown chemical composition, our WEICHAI WP12 Cylinder Head Subassembly is manufactured from virgin GG25/HT250 material with documented mill certificates. This guarantees consistent hardness (190–240 HB) and thermal expansion behavior matching the original engine block. We also provide bare castings for workshops that prefer to install their own valve guides and seats.
Each subassembly includes pre-installed valve guides and seats machined to the correct interference fit (0.04–0.07 mm). End-users save on machine shop costs because the head is ready for valve lapping and final assembly. For high-mileage rebuilds, we also offer oversize valve guides (0.25 mm, 0.50 mm) to correct worn guide bores without replacing the entire casting.
Technical support is available via email with detailed torque sequences (stage 1: 100 Nm, stage 2: 240 Nm, stage 3: +90° angle for torque-to-yield bolts). We also provide troubleshooting guides for symptoms like coolant loss (cracked water jacket) or white smoke (leaking injector bore). Our goal is to make your WP12 engine restoration straightforward and cost-effective.
For large fleets, we offer sample testing: order one WEICHAI WP12 Cylinder Head Subassembly first for trial installation. If satisfied, volume pricing applies. Many return customers report over 600,000 km of trouble-free operation after replacing their warped original heads with our subassemblies. Additionally, we stock both standard compression (17.5:1) and low-compression (16:1) versions for different emission levels.
Beyond the checklist above, pay attention to engine starting behavior. Hard starting or excessive white smoke on cold starts may indicate a cracked cylinder head or leaking injector sleeve. A simple pressure test of the cooling system (pressurize to 1.2 bar and watch for drop) can confirm head integrity without disassembly.
For vehicles operating in dusty environments (mines, quarries, construction sites), clean the crankcase ventilation system every 10,000 hours. Clogged breathers increase crankcase pressure, which can force oil past the valve stem seals into the combustion chamber, creating carbon deposits on the WEICHAI WP12 Cylinder Head Subassembly’s valve seats.
If the engine overheats due to a failed fan clutch or radiator blockage, stop immediately and allow it to cool. Then inspect the cylinder head for warpage using a precision straightedge and feeler gauge. Maximum allowable distortion is 0.10 mm across the length. Warpage beyond this requires resurfacing or replacement of the WEICHAI WP12 Cylinder Head Subassembly.
Finally, maintain a logbook of all maintenance actions: dates, torque values used, gasket part numbers, and any abnormal findings. This historical data helps predict when the WEICHAI WP12 Cylinder Head Subassembly might need replacement based on actual operating conditions rather than arbitrary mileage intervals.
In summary, the WEICHAI WP12 Cylinder Head Subassembly stands out for its robust construction, precise machining, and ability to withstand the harshest operating cycles. Whether you are rebuilding a HOWO dump truck or a marine generator, choosing a quality cylinder head subassembly directly impacts engine longevity and fuel economy. Always verify the part numbers against your engine serial number before ordering.
For workshops performing in-frame overhauls, we recommend ordering the WEICHAI WP12 Cylinder Head Subassembly together with a complete gasket kit, new bolts, and a water pump to ensure all cooling system components are renewed simultaneously. This approach eliminates hidden failures and gives your customer a worry-free warranty period.
Our inventory includes both standard compression ratio (17.5:1) and low-compression (16:1) versions for different emission levels. The standard WEICHAI WP12 Cylinder Head Subassembly suits Euro III and Euro IV engines, while the low-compression variant is for Euro V engines with higher boost pressures. Select accordingly.
We also provide after-sales documentation including dimensional inspection reports and material certificates upon request. Every WEICHAI WP12 Cylinder Head Subassembly is packaged in anti-corrosion oil and foam-lined boxes to prevent damage during shipping. Bulk orders receive custom palletizing and export documentation assistance.
All specifications are based on original WEICHAI WP12 engine technical data. Actual product dimensions may vary by sub-model (E3, E5, NG, etc.). Always cross-check part numbers with your engine’s serial number plate.
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