Complete Cylinder Head Assembly for Nissan K25 / K21 Engine — OEM 11040-FY501 / 11040FY501

This complete cylinder head assembly (OEM part numbers 11040-FY501 and 11040FY501) is manufactured to exact specifications for the Nissan K25 and K21 industrial engines used in Nissan 1-3.5 ton forklifts. The K-series engines — particularly the K25 2.5-liter 4-cylinder — are among the most reliable and widely deployed forklift powerplants globally, found in Nissan Forklift models including the DX, LX, Nomad, Platinum, and J Series. The cylinder head is the single most critical engine casting, responsible for sealing combustion chambers, housing the complete valve train, directing intake and exhaust flow through precision ports, and managing engine temperature through integrated coolant passages. When a K25 cylinder head fails — typically from overheating-induced warpage, valve seat recession from prolonged LPG operation, or cracking between valve seats — the symptoms include coolant loss, white exhaust smoke, cylinder-to-cylinder compression leakage, and hard starting that requires complete head replacement.

Cast from premium alloy iron with a controlled pearlitic microstructure for thermal fatigue resistance, this cylinder head matches the original Nissan K25/K21 design in every critical dimension. All machined surfaces — including the deck face, camshaft bore, valve seats, injector sleeves, glow plug bores, and manifold mounting flanges — are CNC-machined to factory tolerances. The deck surface is precision-ground to 0.03mm flatness or better, ensuring a leak-free seal with the MLS (multi-layer steel) head gasket. Valve seats are machined with multi-angle profiles for maximum flow efficiency and heat dissipation, and pre-installed valve guides are reamed to Nissan OE clearance specifications. Each head undergoes individual hydraulic pressure testing of both coolant and oil passages before final inspection, eliminating the risk of internal porosity leaks after installation.

Direct replacement for Nissan K25 and K21 engines in Nissan Forklift 1-3.5 ton diesel and LPG models (DX, LX, Nomad, Platinum, J, F, UD series). Always replace with new head bolts (Nissan specifies torque-to-yield bolts on these engines), a new MLS head gasket, and intake/exhaust manifold gaskets. Follow the Nissan factory torque sequence and angle-tightening procedure precisely — incorrect torque can cause gasket failure within hours. Browse our engine parts collection for complementary components. Reference OEM specifications at Nissan Forklift official site.

Technical Specifications

• SKU: 11040-FY501
• OEM Numbers: 11040-FY501 / 11040FY501
• Type: Complete Cylinder Head Assembly with Valves & Valve Train
• Material: Premium Alloy Cast Iron, CNC Machined
• Fitment: Nissan K25 2.5L / K21 2.1L Diesel & LPG Engines
• Application: Nissan Forklift 1-3.5 Ton — DX, LX, Nomad, Platinum, J Series

Compatible Nissan Forklift Models

Kingstream K-series cylinder heads are individually pressure-tested, oil-misted on all machined surfaces, vacuum-sealed in VCI anti-corrosion barrier film, and packed in high-density foam inserts within reinforced export cartons. Full QC documentation including pressure test report is provided. 12-month warranty. Contact us with your engine serial number for fitment verification, bulk pricing, and freight quotations.