Cylinder Head 5274388 4929283 – Cummins ISB QSB 4B 6BT

Cylinder Head 5274388 / 4929283 — Cummins ISB / QSB / B4.5 / 4BT / 6BT Diesel Engine Cylinder Head Assembly

This cylinder head assembly part numbers 5274388 and 4929283 (also cross-reference 5274389) is a Kingstream OEM complete cylinder head for Cummins ISB, ISBE, QSB4.5, 4BT, and 6BT 3.9-5.9L diesel engines in construction machinery, marine vessels, heavy-duty trucks, generator sets, and forklift applications. The Cummins B-series is one of the most widely produced industrial diesel engine families in history — the cylinder head houses the intake and exhaust valves, valve springs, fuel injectors, glow plugs, and coolant passages while sealing the top of the cylinders against combustion pressures exceeding 2000 psi. 44kg with 61×34×15cm neutral packaging. 12-month warranty (also listed as 6-month). MOQ 1 piece. 100% professional tested. Ships by sea freight with 7-25 day delivery. Professional after-service with remote online support. Kingstream OEM quality for Cummins B-series engine fleet operators.

INSTALLATION PROCEDURE: Step 1 — Drain engine coolant and engine oil. Disconnect battery. Step 2 — Remove the valve cover, rocker arm assembly, pushrods, intake and exhaust manifolds, turbocharger, fuel lines, and injectors from the cylinder head. Step 3 — Remove the cylinder head bolts in the reverse sequence of the torque pattern — failure to follow the correct sequence can warp the cylinder head. Step 4 — Using an overhead crane or engine hoist, carefully lift the old cylinder head off the engine block. Step 5 — Thoroughly clean the engine block deck surface with a gasket scraper — the surface must be absolutely clean, flat, and free of any old gasket material, carbon deposits, or debris. DO NOT use abrasive discs or power tools that can remove metal from the deck surface. Step 6 — Inspect the block deck for flatness using a precision straightedge and feeler gauge. Maximum allowable warpage per Cummins specification. Step 7 — Check cylinder liner protrusion above the deck — incorrect protrusion causes head gasket failure. Step 8 — Clean all cylinder head bolt holes in the block — use a thread chaser tap, NOT a cutting tap, to avoid removing metal. Blow out bolt holes with compressed air. Oil or coolant in bolt holes can cause hydraulic cracking of the block during bolt torque. Step 9 — Position the new head gasket on the block — verify correct orientation per the “TOP” or “FRONT” marking. Step 10 — Carefully lower the new cylinder head onto the block using guide pins or dowels for alignment. Step 11 — Apply clean engine oil to the head bolt threads and underside of bolt heads. Step 12 — Install all head bolts finger-tight, then follow the Cummins torque sequence: typically a multi-step process of torque to an initial value, then an additional angle torque (e.g., 90 ft-lbs + 90°). Step 13 — Reinstall pushrods, rocker arm assembly, and torque rocker shaft bolts. Step 14 — Adjust intake and exhaust valve lash to Cummins specification. Step 15 — Reinstall injectors, fuel lines, manifolds, turbocharger, and valve cover with new gaskets. Step 16 — Refill coolant and oil. Prime the fuel system. Step 17 — Before starting, crank the engine with fuel shut off to build oil pressure. Step 18 — Start engine and immediately verify oil pressure, coolant flow, and check for leaks. Run engine to operating temperature and re-torque head bolts if required by Cummins procedure. 12-month warranty. Kingstream OEM.

SYMPTOMS OF CYLINDER HEAD FAILURE: Coolant in engine oil (milky oil from cracked head or failed head gasket), white exhaust smoke (coolant entering cylinders), engine overheating with no external coolant leaks, loss of compression between adjacent cylinders, external coolant or oil leaks from the head gasket joint, excessive blow-by and crankcase pressure, and visible cracking in the cylinder head surface. For Cummins ISB/QSB/4BT/6BT diesel engine fleet overhaul programs, contact us. Kingstream OEM.

Technical Specifications

100% tested. MOQ 1 PC. Kingstream OEM. Contact us.