G3408 and G3412 Engines Caterpillar

Magneto

In order to perform a test of the magneto on the engine, check the condition (intensity) of the spark at the spark plug.

Perform a test of the magneto when the magneto is off of the engine. This test can be used to find a defect in the electrical components. A magneto test bench is used to perform the tests.

Finding The Piston Top Center Position For The No. 1 Piston On The Compression Stroke

9S-9082 Engine Turning Tool

Start all timing adjustments for the engine with the No. 1 piston on the top center compression stroke.

Illustration 1	g00580752
Timing Cover (1) Cover. (2) Cover.

1. Remove the cover (1) for the timing pointer from the right side of the flywheel housing.

2. Remove cover (2). Use the 9S-9082 Engine Turning Tool to turn the flywheel in the direction of engine rotation. Turn the flywheel so that the No. 1 piston is on the top center compression stroke. There will be 0 degrees on the flywheel.

   Note: Check the 0 degree mark on the flywheel. Compare this mark to the pointer in the flywheel housing. If the mark has turned past the pointer, the flywheel must be adjusted. The flywheel must be turned 30 degrees in the clockwise direction. Repeat Step 2. This will prevent timing errors that may be caused by play in the timing gears.

3. Remove the left front valve cover. Look at the valves of the No. 1 cylinder. The valves will be closed if the No. 1 piston is on the compression stroke. You should be able to move the rocker arms up and down with your hand. If the No. 1 piston is not on the compression stroke, go on to Step 4.

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Illustration 2	g00600511
Flywheel Timing Marks

4. The intake valves and the exhaust valves for the No. 1 cylinder should be closed. If these valves are open, turn the flywheel in the direction of engine rotation. The flywheel must be turned 360 degrees. If both valves are now closed, this is the piston top center position.

   Note: Check the 0 degree mark on the flywheel. Compare this mark to the pointer in the flywheel housing. If the mark has turned past the pointer, the flywheel must be adjusted. The flywheel must be turned 30 degrees in the clockwise direction. Repeat Step 4. This will prevent timing errors that may be caused by play in the timing gears.

Timing Of Magneto To Engine

1. Turn the crankshaft in the direction of engine rotation until the No. 1 piston is coming up on the compression stroke. Refer to Finding Piston Top Center Position For The No. 1 Piston On The Compression Stroke.

2. Turn the crankshaft until the desired timing mark is directly under the flywheel pointer. Refer to the Engine Performance Book, "Fuel Usage Guide" .

3. Remove the timing bolt (1) when the magneto is off of the engine. Rotate the magneto drive until the yellow mark on the gear is in the center of the hole.

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Illustration 3	g00580800
Fairbanks Morse Magneto (1) Timing bolt.

4. Position the drive slots for the magneto in the proper position for timing of the engine. The drive coupling can be pulled out of the magneto drive housing. Then, the drive coupling can be positioned and the drive coupling can be pushed in for engagement.

5. Install the magneto. The drive tang and the slot will engage.

6. Make the final timing adjustment by rotating the magneto at the drive housing mounting. Use a timing light when the engine is running at rated speed.

   Note: Timing must NOT be made at low idle because of the timing advance in the magneto.

Timing The Ignition System

Use a 5P-6584 Caterpillar Timing Light. Lock the clip around the primary wires. Lock the clip to the transformer for the No. 1 cylinder. Pulling the wires out of the protective plastic conduit is required. No disassembly is needed.

Timing Of Magneto To Engine

1. Turn the crankshaft in the direction of engine rotation until the No. 1 piston is coming up on the compression stroke. Refer to Finding The Piston Top Center Position for No. 1 Cylinder On The Compression Stroke.

2. Turn the crankshaft until the desired timing mark is directly under the flywheel pointer. Refer to the Engine Performance Book, "Fuel Usage Guide" .

3. The magneto timing marks (1) must be in alignment when the No. 1 piston is at the correct BTC position.

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Illustration 4	g00580806
Typical Example Of Altronic Magneto Timing Marks (1) Timing marks.

4. If this is not correct, remove the magneto from the engine.

5. Put the timing marks (1) in the correct position. The drive tang (2) should be positioned with the timing marks.

6. Make sure that the drive slots for the magneto are in the correct position. The drive coupling can be pulled out of the magneto drive housing. Then, the drive coupling can be positioned and the drive coupling can be pushed in for engagement.

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Illustration 5	g00580835
Drive Tang (1) Drive tang.

7. Install the magneto. The drive tang and the slot will engage.

8. Make the final timing adjustment. Rotate the magneto at the drive housing mounting. Use a timing light when the engine is running at rated speed.

   Note: Timing must NOT be made at low idle because of the timing advance in the magneto.

Timing Of The Engine

The 163-6164 Timing Control has an application switch and a timing switch. These switches are located on the right side of the box. The 163-6108 Timing Control also has these switches in the same location. The application switch is on the top. This switch must be set to the engine model that is controlled. The switch must also be set to the timing range that is appropriate for the fuel that is consumed. The timing switch is used to fine tune the ignition timing. The following steps describe the procedure that is used to set the ignition timing.

1. Determine the engine model that will be controlled. One example of an engine model is the G3408. Another example of an engine model is the G3412.

2. Perform an analysis of the fuel in order to determine the methane number. Use the Engine Performance Book to determine the ignition timing. You may consult with your local Caterpillar dealer in order to determine the ignition timing.

3. Set the application switch to the appropriate model and the appropriate timing range.

   Note: Choose the appropriate setting for the application switch. The desired timing should be in the upper end of the lowest timing range.

   • For example, the desired ignition timing for a G3408 Engine is 23° BTC. The setting for the switch should be "C".

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   Table 1

   APPLICATION SWITCH (1)
   WARNING IN ORDER TO AVOID ENGINE SHUTDOWN OR DAMAGE TO THE ENGINE, DO NOT CHANGE THE SETTING WHEN THE ENGINE IS RUNNING.	A = G3304	10° to 25° BTC
   	B = G3306 / G3406	10° to 25° BTC
   	C = G3408	10° to 25° BTC
   	D = G3304	20° to 35° BTC
   	E = G3306 / G3406	20° to 35° BTC
   	F = G3408	20° to 35° BTC

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   ( 1 )

   Label For The Application Switch

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Illustration 6	g00582974
Caterpillar Digital Ignition System (1) Application switch (2) Timing switch (3) Connection for the power and timing sensor (4) Connection for ignition wiring (A) 224.9 mm (9 inch) (B) 196.3 mm (7.7 inch) (C) 14.3 mm (0.5 inch) (D) 181 mm (7 inch) (E) 158.8 mm (6.3 inch) (F) 11.1 mm (0.4 inch)

4. The timing switch is fully advanced at location 15, and the switch retards one degree for each mark as the switch is moved to zero. Use the same example that was used in Step 3. Set the timing switch to 15. Set the switch to a setting that is two positions toward the zero position. This movement will place the timing close to the correct setting.

5. Start the engine and verify the ignition timing with a timing light. The timing switch may need to be moved. This is a small adjustment of only one or two positions in either direction. These adjustments will help to attain the correct timing.

6. Install the switch covers and the thread lockwire through the holes in the cover. Secure these items with a lockwire cap. This cap will prevent unauthorized tampering with the setting for the ignition timing.

Timing The Ignition System

Use a 5P-6584 Caterpillar timing light. Lock the clip for the timing light around the secondary wire for the ignition. Lock the clip between the transformer for the No. 1 cylinder and the boot for the valve cover. No disassembly is required.

Spark Plug Adapter

Illustration 7	g00648699
Spark Plug Adapter (1) Adapter. (2) Seal. (3) Cylinder head. (4) Gasket.

The rubber boot must be installed on the valve cover for the spark plug adapter. The seal must be installed on the valve cover. This prevents water, dirt or other foreign material from entering the adapter. If this happens, detonation may occur. Early engine ignition may occur. Put liquid soap on seal (2) on the adapter before installation. Put 5P-3931 Anti-Seize Compound on the threads of adapter (1) and on the threads in the cylinder head (3) .

Tighten the adapter to the following torque. ... 95 ± 7 N·m (70 ± 5 lb ft)

Spark Plug And Transformer

The following tools are needed:

• 2P-5481 Deep Well Socket

• 9V-6695 Strip

• 154-9521 Spark Plug Seat Cleaner

Illustration 8	g00579964
Altronic Spark Plug And Transformer (1) Transformer. (2) High voltage wire assembly. (3) Rubber boot. (4) Spark plug. (5) Seal.

Two different manufacturers of ignition systems have been used on the G3408 Engine and on the G3412 Engine. Altronic is the current manufacturer of Caterpilllar ignition systems. Fairbanks Morse was the manufacturer of the former ignition systems.

Illustration 9	g00646486
Externally mounted transformer

Illustration 10	g00646516
Location of the seal (6) Adapter tube for the spark plug. (7) Dimension "A".

Dimension "A" (2) is equal to the following amount. ... 5 ± 1 mm (0.20± 0.04 inch)

A magneto can have a transformer that is mounted externally, and a CDIS can have a transformer that is mounted externally. These ignition systems can have integral transformers as well. The integral transformers are installed on top of the spark plug.

Illustration 11	g00579962
Integral transformer (8) Adapter. (9) Seal. (10) Cylinder head. (11) Gasket.

With the integral installation, the spark plug should be installed first. Torque the spark plug to 30 ± 4 N·m (22 ± 3 lb ft). Ensure that the copper gasket is on the top of the spark plug. Install the transformer. Tighten the transformer by hand. Tighten the transformer one-eighth turn more. Do not exceed 6.75 N·m (5 lb ft) of torque.

The magneto and the CDIS use an externally mounted transformer (1) with a secondary high voltage wire (2). This wire is between the transformer and the spark plugs (5) .

This transformer and plug assembly is an integral unit. This assembly is mounted in the adapter in the cylinder head. The transformer (6) and the spark plug (8) are assembled together before installation in the adapter.

The torque for the assembly is the following amount. ... 47 ± 3 N·m (35 ± 2 lb ft)

Note: On engines that are equipped with a magneto, the copper washer that is supplied with the spark plug (8) must be removed. Install a copper spacer (7) on a new spark plug (6).

Illustration 12	g00648705
Earlier Version Of The Fairbanks Morse Spark Plug And Transformer (12) Transformer. (13) Copper spacer. (14) Spark plug.

Make reference to page 8 of this manual.

The amount of voltage that is needed in order to cause the spark will change. This change will occur with a change in the conditions of the spark plug. Changes in engine load may also change the amount of voltage that is needed to cause the spark. A new spark plug will use 3,000 to 6,000 volts in an engine that is operating at low idle. At full load, this voltage will be 8,000 to 10,000 volts. The voltage that is needed in a spark plug that has a gap adjustment is 10,000 volts. Spark plugs will cause the engine to run roughly, if the spark plug voltage needs to be increased to 10,000 volts.

Spark plug gap must be kept at 0.380 mm (0.015 inch). The 9U-6695 Firing Indicator is an aid for detecting ignition problems. Follow the instructions that come with the tool.

Spark plugs must be installed to the following torque of 30 ± 4 N·m (22 ± 3 lb ft) with the 2P-5481 Deep Well Socket. Tighten the transformer by hand. Tighten the transformer one-eighth turn more. Do not exceed 6.75 N·m (5 lb ft).

Do not overtighten the transformer or the spark plug.

Illustration 13	g00648710
Later Version Of The Fairbanks Morse Spark Plug And Transformer (15) Rubber boot. (16) Seal.

Be sure that the seal (11) is installed correctly. This seal should prevent any oil leakage from the crankcase. Oil leakage could enter the spark plug adapter.

Manual Stop Switch

The manual stop switch (1) is located below the instrument panel on the right side of the engine. This switch should be used in an emergency situation. Under normal conditions, stop the engine by shutting off the supply of gas.

Illustration 14	g00580844
Manual Stop Switch (1) Switch.