Nissan K21/K25 Complete Cylinder Head 91H20-00310 / 11040-FY501 — Forklift LPG Engine, JAPKOR Warranty

This is a complete cylinder head assembly for the Nissan K21 (2.1L) and K25 (2.5L) 4-cylinder LPG engines — the standard power units in Nissan F01 series forklifts manufactured from 1975 to 1996, and still widely in service today across global markets. Unlike the diesel cylinder heads that dominate Chinese-brand forklifts, the K21/K25 cylinder head is an aluminum casting designed for spark-ignited LPG operation with lower compression ratios, different valve seat materials (hardened for dry LPG fuel), and spark plug threads instead of injector bores. Multiple OEM cross-references confirm this head’s broad compatibility: FY5A-FY54A (engine family code), 91H20-00310, 11040-FY501, 11040FY501, 8774004, 91H2000310, 50452531, W505010131, and SY937496 — covering Nissan OEM, aftermarket, and multi-language catalog numbering systems. The cylinder head seals the combustion chamber, houses the intake and exhaust valves, valve springs, spark plugs, and provides the rocker arm mounting points and oil drain-back passages. A cracked or warped K21/K25 aluminum head — often caused by overheating from a failed water pump or low coolant — causes coolant loss into the combustion chamber (white exhaust smoke), compression loss between adjacent cylinders, or oil-to-coolant cross-contamination.

This JAPKOR-brand cylinder head is manufactured in Zhejiang, China with an industry-leading 18-month warranty. Dimensions: 50×24×16 cm, 9 kg gross weight (50×21×16 cm carton, multiple cartons per pallet). Customized logo available (MOQ 15 pieces), customized packaging (MOQ 50), and graphic customization (MOQ 50). When installing an aluminum cylinder head, always replace the head gasket and cylinder head bolts — the bolts on the K21/K25 are torque-to-yield (TTY) fasteners that stretch permanently during the first installation and cannot be reused without risking head gasket failure. Verify the cylinder head deck surface for warpage using a precision straightedge and feeler gauge — aluminum heads warp more easily than cast iron heads, and a warped head will not seal even with a new gasket. Follow the factory torque sequence and angle specifications exactly — K21/K25 engines use a multi-step torque procedure (initial torque to a low value, then an angle rotation in a specific sequence). Apply clean engine oil to the bolt threads and underside of the bolt heads before installation to ensure accurate torque-to-yield readings.

Compatible with Nissan F01 series forklifts (1975-1996) with K21 and K25 LPG engines. Browse our cylinder head cover selection for valve covers. For engine specifications, visit Nissan Forklift official website.

Technical Specifications

Compatible Models

18-month warranty. Replace head bolts and gasket. Confirm your Nissan forklift model →