ISOLATOR 9Y5292 - Caterpillar

Engine: G3516C (S/N: GSB1-UP; TJB1-UP; TJC1-UP; GZZ1-UP; RWA1-UP; DKR1-UP) G3516E (S/N: GAS1-UP; SLY1-UP; GHP1-UP) G3520C (S/N: MAD1-UP; GZJ1-UP; GZK1-UP; GZL1-UP; GZM1-UP; GZN1-UP; B9P1-UP; HAT1-UP; CWW1-UP; CWY1-UP; GDB1-UP; GHC1-UP; GHE1-UP; JBX1-UP; JBZ1-UP) G3520E (S/N: GZG1-UP; GZH1-UP; HAL1-UP; SXY1-UP; GHM1-UP; GHR1-UP)Introduction
The problem that is identified below does not have a permanent solution at this time. Until a permanent solution is known, use the solution that is identified below.Problem
Failures of the cylinder head valves on some G3500C and G3500E Generator Set Engines have been reported.The aggressive profiles on the camshaft lobes for these engines make the valve lash clearance adjustments and the valve bridge adjustments critical.If the valve lash increases beyond the specification, the valve will seat while the valve lifter is traversing the aggressive profile of the camshaft lobe. On this part of the camshaft lobe, the valve is traveling at a velocity that is beyond the specification for seating the valve. The increased velocity during seating causes an increased load on the valve stem. The increased load on the valve stem may lead to failure of the valve. Any increase in valve lash that is beyond the specification may cause failure of the valve.Solution
The correct valve lash clearance adjustments and valve bridge adjustments is critical. The recommendation for adjustment of the valve lash has been updated for all G3500C and G3500E engines.The valve recession must also be checked during adjustment of the valve lash and the valve bridges. Record these measurements. This will provide a history of valve recession. History of valve recession is used to indicate wear of the valve and of the valve seat. Valve Clearance Adjustments
The 147-5482 Valve Lash Gauge Group must be used in order to adjust the valves and the valve bridges for these engines.The crankshaft position for valve lash settings must begin with the number one piston at Top Center (TC). The flywheel must be pinned prior to the start of the valve adjustment. Refer to Systems Operation/Testing and Adjusting, RENR5978, "Finding the Top Center Position for the No. 1 Piston" for information.Check the clearance between the valve bridge and the valve rotator for each valve. Also, perform a visual inspection of the clearance between the rotators and the valve cover base. Correct any problems that are found.Valve Adjustments after Replacement of the Cylinder Head
Preliminary adjustments must be made when a cylinder head has been replaced. Perform this procedure regardless of the reason for the replacement of the cylinder head. For each Step, adjust the valves to the following specifications:G3500C and G3500E with 1800 Rpm Exhaust valve clearance ... 1.02 mm (0.040 inch) Intake valve clearance ... 0.38 mm (0.015 inch)G3500C and G3500E with 1200 Rpm and 1500 Rpm Exhaust valve clearance ... 1.12 mm (0.044 inch) Intake valve clearance ... 0.38 mm (0.015 inch)
Complete the valve lash clearance adjustments and the valve bridge adjustments prior to starting the engine.Make these adjustments for each cylinder head that has been replaced.
Start the engine and operate the engine at full load for one hour.
After