879853A01 Mercury BEARING ASSEMBLY, Roller (UPPER)

Do not operate or work on this machine unless you have read and understand the instructions and warnings in the Operation and Maintenance Manual. Failure to follow the instructions or heed the warnings could result in injury or death. Contact any Caterpillar dealer for replacement manuals. Proper care is your responsibility.
Personal injury can result from rotating and moving parts. Stay clear of all rotating and moving parts.Never attempt adjustments while the machine is moving or the engine is running unless otherwise specified.The machine must be parked on a level surface and the engine stopped.Attach a "Do Not Operate" or similar warning tag to the start switch and controls before servicing, repairing, or making adjustments to the machine.
Ignition systems can cause electrical shocks. Avoid contacting the ignition system components and wiring.Do not attempt to remove the valve covers when the engine is operating. The transformers are grounded to the valve covers. Personal injury or death may result and the ignition system will be damaged if the valve covers are removed during engine operation. The engine will not operate without the valve covers.
Introduction
Use the following procedure to check the transformer:Check Preparation
Turn the engine control switch to the OFF/RESET position. Switch the circuit breaker for the engine OFF.
Remove the valve cover of the suspect cylinder.
Pulling on the wiring harness may break the wires. Do not pull on the wiring harness.
Disconnect the ignition harness from the transformer. Remove the transformer from the engine.Check Procedure
Illustration 1 g06583097
(1) Screw
(2) Ground spring
(3) Spacer
(4) Terminal for the spark plug
(5) Extension
(6) O-ring seal
Inspect the body of the transformer and ground spring (2) for corrosion and/or damage. Verify that screws (1) for the ground spring are secure.Note: Punch through causes misfires in the engine that does not generate a diagnostic code.
Check the extension near spacer (3) for signs of punch through (pin holes) and/or arcing.
Inspect O-ring seal (6) inside the extension for damage.
Remove O-ring seal (6). Inspect terminal (4) inside the extension for looseness, corrosion, and/or damage. Insert a spark plug into the transformer and check for spring pressure of terminal (4).
The extension can be scratched and damaged with a wire brush. Do not use a wire brush on the extension.
Clean any deposits from the inside extension. Use a 6V-7093 Brush with isopropyl alcohol.
Illustration 2 g06583103
(1) Screw
(4) Terminal connector
(7) + pin
(8) - pin
Measure the voltage of the diode for the primary circuit.
Illustration 3 g00754013
Symbol for a diode
Set the multimeter to the diode scale. Measure the voltage between positive pin (7) and negative pin (8).
Reverse the polarity of the probe and measure the voltage between the pins again.For the diode of the primary circuit, the correct voltage between the positive pin and the negative pin is approximately 0.450 VDC. When the polarity is reversed, there is no reading.
Measure the resistance of the secondary circuit.
Set the multimeter to the 40,000 Ohm scale. Measure the resistance between screw (1) for the ground spring and terminal (4) for the spark plug.
Switch the suspect transformer with a transformer from a different cylinder that is known to be good. Install the transformers. Install the valve covers.
Reset the control system. Clear any logged diagnostic codes.
Start the engine and operate the engine to generate a diagnostic code.If the problem follows the transformer, replace the transformer. Reset the control system. Clear any logged diagnostic codes.Note: Make sure that you use the correct transformer for the engineIf the problem stays with the cylinder, there is a problem with the spark plug or the electrical circuit for the transformer.For troubleshooting of the electrical circuit, refer to Troubleshooting, SENR6413, "G3500 Engines".For instructions on inspection and replacement of the spark plug, refer to the Operation and Maintenance Manual.