Failures of Cylinder Head Valves on G3500C and G3500E Generator Set Engines{1100, 1105, 1121} 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)

1. 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.

2. Start the engine and operate the engine at full load for one hour.

3. After one hour of operation, adjust the valve lash and the valve bridges again.

   This will compensate for the valve mechanisms initial seating.

Adjustments for Normal Engine Maintenance

Perform valve lash clearance adjustments and the valve bridge adjustments for every 1000 service hours. This is considered to be normal engine maintenance.

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)

Refer to Operations and Maintenance Manual, SEBU7681 for information that is related to the maintenance intervals for your engine.

Replacement Limits for Valve Recession

Use the 155-1536 Valve Recession Tool Gp in order to check the valve recession. The procedure for the measurement of valve recession is provided with the tool. Measuring and recording the valve recession provides information about the wear that has occurred to the valve and to the seat.

Check the valve recession at every 1000 hour service interval. This will give an adequate number of data points for tracking the valve recession. This interval for the measurements replaces the schedule that is published in Operations and Maintenance Manual, SEBU7681 until further notice. The measurements for the valve recession must be recorded and the valve recession must be plotted at each valve adjustment in order to establish a trend for the valve wear.

Check the measurement data for a difference in the valve recession that is greater than 1 mm (0.039 inch) for the valves that share a valve bridge. If this measurement is exceeded for two successive measurements, replacement of the cylinder head is necessary.

For example, one intake valve is measured and a recession of 1.35 mm (0.053 inch) is recorded. If the other intake valve that shares the valve bridge is measured and a recession of 0.35 mm (0.014 inch) is recorded, then the cylinder head must be replaced.

Also, if the recession that is measured for any valve exceeds 2.3 mm (0.091 inch) the cylinder head must be replaced. Refer to Operation and Maintenance Manual, SEBU7681.

If there is a question about replacement of a cylinder head, ask your technical communicator to contact the Caterpillar Dealer Solution Network (DSN) for assistance in determining whether the cylinder head should be replaced.

Information that Must be Reported to the Dealer Solution Network (DSN) in the Event of a Valve Failure

In the event of a valve failure, contact the DSN as soon as possible. A field report must be completed by DSN prior to the repair. The following information will be requested by the DSN in order to complete the field report:

• Engine serial number

• Engine cylinder that failed

• Failure mode

• Engine hours

• Hours on the failed components

• Recent service information (valve lash clearance adjustment and valve bridge adjustment)

• History of the valve recession (intake valve and exhaust valve)

• Records of the engines oil changes (oil type and interval)

• Dealers preference for change interval (service hour interval or oil analysis program)

• Most recent oil sample

• Engines oil consumption rate

• Logged events from the Electronic Control Module (ECM)

• Pertinent engine data that has been logged by the switchgear

Parts that Must be Returned in the Event of a Valve Failure

Prior to returning parts, mark the failed components or tag each of the failed components with the engine serial number.

Return the following parts in the event of a valve failure:

Cylinder head - Return all pieces of the valve that can be retrieved. Do not disassemble the cylinder head.

Damaged pistons - Mark the cylinder number (inboard orientation).

Damaged cylinder liners - Mark the cylinder number (inboard orientation).

Valve bridges - Leave the adjustment screw intact. Mark the bridges for the intake valves and the exhaust valves.

Valve cover base - Mark the cylinder number.

Rocker arms - Mark the cylinder number.

Rocker shaft - Mark the cylinder number.

Pushrods - Mark the pushrods for the intake valves and the exhaust valves.

Lifters - Mark the lifters for the intake valves and the exhaust valves.

Information that is Necessary for Returning Failed Components that have been Involved in Valve Failures

In the event of a valve failure, use the following form to record information for the return of failed components. Ship a copy of the form with each of the components. Attach additional information to this document, if necessary.