Troubleshooting Tips Will Help Maintain Steady Engine RPM{1264, 1280} Caterpillar

Engine:

3304 (S/N: 6YB1-UP; 3TC1-UP; 4PC1-UP; 83Z1-UP)

3304B (S/N: DED1-UP; 1YF1-UP; 2KK1-UP; 9HK1-UP)

3306 (S/N: 2ZC1-UP; 5JC1-UP; 7KF1-UP; 85Z1-UP)

3306B (S/N: B8D1-UP; 1DG1-UP; 3RG1-UP; 2AJ1-UP; 8JJ1-UP; 2TM1-UP; 9NR1-UP; 8NS1-UP; 9DS1-UP; LRW1-UP; 1CZ1-UP)

3406 (S/N: 75Z1-UP)

3406B (S/N: 2WB1-11475; 4JK1-98; 4PM1-UP; 4RG1-UP)

3406C (S/N: 2WB11476-UP; 4JK99-UP; 4ZR1-UP; KPS1-UP; 1LS1-UP; 8FS1-UP; 9ES1-UP; LRX1-UP; 1DZ1-UP)

3406E (S/N: 9NN1-UP; 8AZ1-UP)

3408B (S/N: 2BG1-UP)

3412 (S/N: 2WJ1-UP; 4BZ1-UP; 1EZ1-UP; 3FZ1-UP; 81Z1-UP)

3412C (S/N: BAK1-UP; PTL1-UP; 5FL1-UP; 9EP1-UP; BCW1-UP; BAX1-UP; LRY1-UP)

3456 (S/N: BGA1-UP; CCB1-UP; EPE1-UP; CAH1-UP; GHJ1-UP; CBX1-UP)

Power Module:

PM3412 (S/N: CAJ1-UP)

Introduction

The engine control governor is failing to keep the engine RPM steady on certain 3300/3400 gensets. The following tips will help resolve engine surge problems on mechanical governed 3300/3400 gensets.

Fuel System Gumming Caused by Periods of Extended Shutdown

Tip A: Proper preventive maintenance for standby generator sets will prevent gumming caused by shutdown.

1. Refer to Operations and Maintenance Manual, SEBU6042, "Maintenance Management Schedules For Recommended Preventive Maintenance".

Tip B: Recommended procedures for resolving fuel gumming issues in the field caused by extended storage time.

1. Case 1: Long engine storing time (greater than six months).

   1. Remove governor. Refer to Field Repair Manuals for additional information.

      Note: With governor removed, de-gum or clean the tach shaft, load stop shaft, and Servo Assembly. Settings of the governor should not change.

   2. Remove plunger and barrel assembly (one at a time).

   3. De-gum plunger and barrel assembly with alcohol (or suitable substitute).

   4. Wet the plunger and barrel assembly with a small amount of light oil or fuel.

   5. Re-install the plunger and barrel assembly.

   6. Check the rack movement. Repeat Steps 1.b and 1.e until you have free rack movement.

   7. Re-install the governor. The settings for the governor may have to be verified.

2. Case 2: Moderate engine storage time (greater than four months).

   1. Remove the fuel gallery cover.

   2. Wet each plunger and assembly with alcohol, high-grade fuel, or a suitable substitute. Ensure that alcohol is applied to the hollow dowels that are the fill ports for the fuel.

   3. Rotate the engine crankshaft at least 180°. Repeat Step 2.b twice.

   4. Re-install the gallery cover.

   5. Prime engine with high-grade fuel. Settings of the governor should not change.

3. Case 3: Short engine storage time (greater than two months).

   1. Prime the fuel system with high-grade fuel.

   2. Start the engine. Run the engine with aggressive low to high throttle exercise.

Dashpot Settings and Proper Procedural Adjustment

Tip A: Correction of 3306/3406 standby generator set engines that may go into overspeed during startup (when equipped with dashpot governor arrangements).

Discussion

This is a correctable problem that is somewhat characteristic of 3306 and 3406 governors. The oil drains from the dashpot when the engine has been idle for an extended period of time. As the engine cranks, oil is drawn into the dashpot by the moving dashpot plunger. Oil pressure is not an issue because the dashpot plunger draws unpressurized oil from a cavity in the governor housing. If the dashpot does not fill before the engine reaches 1500 RPM, the engine could run-up to the control system's overspeed trip limit and shutdown.

To alleviate this problem in the past, dealers have used the following methods:

• Used heating blankets in order to keep the governor warm

• Changed to a lower viscosity oil

• Installed a five-second timer to delay the energize-to-run solenoid from actuating

The five-second delay provides five seconds of cranking time before the engine starts. These five seconds allow the dashpot time to fill.

If equipped, the 1724 Actuator Linkage can be moved to the shutoff lever (with modifications to the linkage arrangements). The 1724 would then be able to hold the speed down when the Caterpillar governor goes unstable during startup (before there is enough oil in the dashpot). A jumper would also need to be added so that the engine goes straight to high idle upon startup. This jumper should be connected to Terminal 9 and Terminal 10 on the Woodward 8290 Control. This is the easiest fix for critical standby applications.

If the unit does not have the 1724 option, add the timer (refer to the Solution Section below. Also confirm that the dashpot check valve is not reversed.

Note: The dashpot check valve is used only on 3304 and 3306 models.

The dashpot check valve allows you to draw oil into the governor's dashpot during cranking so that the dashpot is full before the engine reaches 1500 RPM. The dashpot will fill slower than normal under the following conditions:

• The needle valve is adjusted so that it is nearly closed

• The oil is cool/cold and of relatively heavy weight

The needle valve should be turned clockwise until it is completely closed. When the needle valve is completely closed (all the way in), back the valve out (counter-clockwise) anywhere between one-half and two full turns. Ensure that you are using the correct oil and that the needle valve is adjusted correctly.

Note: Certain emissions-certified arrangements have a Woodward 524 Actuator. The Woodward 524 Actuator is used to override the Caterpillar governor via the shutoff linkage. This is not a problem on 3304 and 3306 models equipped with a dashpot check valve because the actuator controls the rack.

Tip B: Check 3306B generator set engine for proper dashpot screw adjustment.

1. For 3306B dashpot screw adjustment, refer to Testing and Adjusting, RENR1287, "3306B Generator Set Engine".

Solution

Perform the following steps for Solutions that can be administered for non-critical standby applications.

Show/hide table

The high voltage that is produced by an operating generator set can cause severe injury or death. Before performing any maintenance or repairs, ensure that the generator will not start. Place the engine control switch in the "OFF" position. Attach "DO NOT OPERATE" tags to all starting controls. Disconnect the batteries or disable the starting system. Lock out all switchgear and automatic transfer switches that are associated with the generator.

1. Lockout genset. Disconnect battery power to the control panel.

2. Install the 3N-7817 Relay Track in the EMCPII Control Panel Subpan. Mount the 3N-5978 On Delay Timer As onto the 3N-7817 Relay Track .

3. Position the 9Y-2921 Relay onto the subpan. Drill the appropriate mounting holes. Use sheetmetal screws to secure the 9Y-2921 Relay to the subpan.

4. Wire the 9Y-2921 Relay and the 3N-5978 On Delay Timer As . For EMCPII Control Panels, refer to Illustration 1. For Electomechanical Control Panels, refer to Illustration 2.

5. Set the timer for a five or six second delay.

6. Reconnect the power source. Return the unit to service.

Illustration 1	g01047021
EMCPII Control Panel

Illustration 2	g01047022
Electromechanical Control Panel

Ensuring That All Governor Throttle Linkage Joints Are Free

Tip A: Visually inspect governor throttle linkage joints to ensure that all are properly lubricated and have free range of movement.

Check Flyweight Assembly Components for Wear (needle bearing, bearing face, and flyweight foot)

Tip A: Refer to Testing and Adjusting, RENR1287, "3306B Generator Set Engine".

Tip B: In 3406C engines, a new governor weight and race has replaced a former governor weight and race. This new weight and race provide a wider contact area between the two parts in order to improve wear resistance and increase service life.

1. Refer to Engine News, SEBD9239 23 September, "New Governor Weight And Race Increase Durability".