G3612 and G3616 Engines Caterpillar

Programming The SCM

The set points that are programmed into the SCM are set at the factory. The set points can be changed in order to conform to the appropriate specifications. This is when the SCM is moved from one engine type to another engine type or when a special setting (usually overcrank or cycle crank) is needed.

Illustration 1	g00326424
Location Of Cover (1) Cover.

Illustration 2	g00326425
Component Location (2) Potentiometer. (3) Rotary switch. (4) Momentary switch.

Programmability

The information for the Set Point is stored. The information for the Set Point is used in the control strategy of the SCM. To program the SCM, perform the following steps:

1. Turn the MCS to the STOP position.

Note: Do NOT open cover (1) in a humid environment. Replace cover (1) as soon as possible.

2. Remove access cover (1) on the back side of the SCM. Potentiometer (2) , rotary switch (3) and momentary switch (4) are visible. Note the position of rotary switch (3) .

3. Turn the rotary switch (3) to the position that corresponds to the set point that is needing adjustment. The LCD display now shows the position of the rotary switch and the related data.

4. Press momentary switch (4) . The data information that corresponds to the position of the potentiometer will flash.

5. Adjust potentiometer (2) in order to change the desired data that is flashing. Once the data is correct, press momentary switch (4) . The data information stops flashing. Reprogramming the set point is now complete.

6. Repeat Step 3 through Step 5 in order to program another set point.

7. Return the rotary switch (3) to position "0" if the system has a fuel solenoid that is Energize To Run (ETR). Return the rotary switch (3) to position "1" if the system has a fuel solenoid that is Energize To Stop (ETS).

   Note: If the following conditions occur, consult Caterpillar Inc. concerning alterations to the specified set points for the engine. The engine does NOT run when in the program mode. The position of the rotary switch does NOT correspond to the operating mode that is programmed into set point "02" .

8. Turn the MCS to the OFF/RESET position.

9. Apply a continuous bead of 6V-6640 RTV Silicone Sealant to the seal surface of cover (1) . Install cover (1) . Install an 8C-4653 Security Seal on access cover (1) in order to prevent unauthorized tampering.

Set Points

02 - ETR/ETS : This set point value will describe the operating mode (type of fuel solenoid) of the SCM.

0 or 2 programs the SCM to operate with an Energized To Run (ETR) gas shutoff valve.

1 or 3 programs the SCM to operate with an Energized To Shutdown (ETS) gas shutoff valve.

2 or 3 programs the SCM to ignore the pressure or the temperature module faults. The high oil temperature, the low oil pressure and the sensor module malfunction will NOT shut down the engine.

03 - Metric/English : A set point value of 0 will command the SCM to display the engine parameters in English units of measurement. A set point value of 1 will display the Metric units of measurement. See the chart that follows:

Table 1

Parameter	Metric/English
Engine Oil Pressure	kPa/psi
Engine Oil Temperature	Degrees C/Degrees F
DC Volts	Volts/Volts
RPM	RPM/RPM
Service Meter	Hours/Hours

04 - Ring Gear Teeth : The value of this set point must be same as the number of teeth on the ring gear. The range of values are 95 to 350.

05 and 06 - Overspeed : The set point for the overspeed shutdown is programmed with the rotary selector switch in the 05 position or 06 position. Position 05 has a range of 400 to 2950 rpm. Position 06 has a range of 2450 to 5000 rpm with increments of 10 rpm. Place the rotary switch in 05 or 06 position. The position that corresponds with the specified set point for the overspeed shutdown.

Note: After programming the 05 or 06 set point, both set points are the same value.

07 - Crank Termination Speed : Once the engine speed passes this set point, the starting motor is no longer energized. Range is 100 to 1000 rpm in increments of 10 rpm.

08 - Oil Step Speed : Once the engine speed increases past this set point, the SCM considers the engine is above the low idle condition in regard to low oil pressure shutdown and alarm. The range is 400 to 1800 rpm in increments of 10 rpm.

09 - Rated Oil Pressure Shutdown : The SCM enters a low oil pressure shutdown condition if the following two conditions are met. The engine lube pressure drops below this set point. The engine speed has exceeded the oil step speed for nine seconds. The range is 34 to 420 kPa (5 to 60 psi). An alarm signal is sent to the annunciator module at 34 kPa (5 psi) above the shutdown.

10 - Idle Oil Pressure Shutdown : The SCM enters a low oil pressure shutdown condition if the following three conditions are met. The engine lube pressure drops below this set point. The engine has been running for more than nine seconds. The engine speed is below the oil step speed. The range is 20 to 336 kPa (3 to 50 psi). The alarm signal is sent to the annunciator module at 34 kPa (5 psi) above the shutdown.

11 - High Oil Temperature Shutdown : If the engine oil temperature has exceeded the set point for 10 seconds, then the SCM enters a high coolant temperature shutdown condition. The range is 95° to 120°C (203° to 248°F). The alarm signal is sent to the annunciator module at 6°C (11°F) below the shutdown temperature.

12 - Low Oil Temperature Alarm : If the engine coolant temperature is less than this set point for two seconds, then the SCM sends an alarm signal to the optional annunciator module. The range is 10° to 30°C (50° to 86°F) .

13 - Overcrank Time : Overcrank time is the amount of total time that is needed in order to start the engine. This time is from when first asked to start until overcrank is indicated. The range is 10 to 360 seconds.

14 - Cycle Crank : Cycle crank is the amount of time that the starting motor cranks. Also, the amount of time that the starting motor rests during a cycle crank. The range is 5 to 300 seconds.

15 - Cool Down : Cool down is the amount of time that the engine is allowed to run after the initiation of a normal shutdown. The range is 0 to 30 minutes.

Table 2

G3600 Engine Status Control Module Settings
Set Point Switch #	Description	Metric Value	English Value
02	ETR/ETS	0	0
03	Metric/English	1	0
04	Ring Gear Teeth	255	255
05	Overspeed	1017	1017
	900 rpm rating
	1000 rpm rating	1130	1130
06	Overspeed	N/A	N/A
07	Crank Terminate Speed	250	250
08	Oil Step Speed	600	600
09	Rated Oil Pressure s/d	(207 kPa)	(30 psi)
10	Idle Oil Pressure s/d	(69 kPa)	(10 psi)
11	High Oil Temperature s/d	(98°C)	(208°F)
12	Low Oil Temperature Alarm	N/A	N/A
13	Overcrank Time	300 sec	300 sec
14	Cycle Time	30 sec	30 sec
15	Cool Down	0 sec	0 sec

SCM Relay Module Service

The relay module is the housing that contains the fuses and terminals 16 to 27. The relay module is part of the back of the SCM.

1. Disconnect the wire from terminal strip 1 in the remote control panel. Check in order to be sure that there is no voltage on the B+ terminal of the SCM. Some of the harness may need to be removed for easy accessibility. Moisture can be introduced into the SCM when the relay housing is removed. Remove the relay housing in a fairly dry environment. Open this housing in an air conditioned area if relative humidity exceeds 60 percent.

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Illustration 3	g00326426
Location Of Relay Housing (1) Relay housing. (2) Screws.

2. Remove screws (2) and washers that hold relay housing (1) to the main housing. To open the housing, install the forcing screws in the two threaded holes. The threaded holes are on the ends of the housing flange and in the same bolt pattern as screws (2) . Tighten the forcing screws. If necessary, insert the thin blade of a knife between the relay housing (1) and the main housing. Drive the blade into the gap by tapping the blade gently in order to break loose the seal.

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Illustration 4	g00326427
Relay Locations (3) "K7" Fuel Control Relay (FCR). (4) "K6" Magneto Shutoff Relay (MSR). (5) "K1" 2301A Ramp (2301A ). (6) "K5" Run Relay (RR). (7) "K2" Fault Shutdown Relay (ENFR). (8) "K4" Starting Motor Relay (SMR). (9) "K3" Crank Termination Relay (CTR).

3. Open the housing and locate the relay or the relays that need to be changed. The relays are tagged "K1" through "K7" on the PC board.

4. Remove the relay clip. Pull the relay straight out.

5. Do the Relay Performance Test. Check continuity with the ohmmeter by using the following method:

   1. With no power on terminals 7 and 8, there should be 1 ohm or less between terminals 1 and 5. There should also be 1 ohm or less between terminals 2 and 6. Coil resistance between terminals 7 and 8 should be 140 to 180 ohms.

   2. Apply 12 volts to terminals 7 and 8. There should be 1 ohm or less between terminals 3 and 5. There should be 1 ohm or less between terminals 4 and 6. There should be 100k ohm or more resistance between any other pairs of terminals.

6. Replace the relay if the relay fails this test. Put the clip back on.

7. Check the connector that is going from the main housing of the SCM to the relay PC board in order to ensure that the connector is still inserted properly.

8. If replacing the relay does not fix problem or if the relay is not defective, then replace the entire relay module.

9. Clean and apply 4C-9500 Quick Cure Primer to the sealing surfaces of both of the housings.

10. Apply a continuous bead of 6V-6640 RTV Silicone Sealant to the main housing sealing surface.

11. Install relay housing (1) on the main housing of the SCM. Fasten the housing with the original washers and screws (2) .

12. Reconnect the wires that were removed.

SCM Alarm Module (DC Voltage Alarm Set Point Adjustment)

Illustration 5	g00326428
Location Of Plug (1) Plug.

For all alarm applications, the set point for the low DC volts alarm is adjusted by a potentiometer. The set point is located under access plug (1) on the rear of the module. The adjustment range is 8 to 38 volts. In order to adjust the low DCV alarm set point, follow the procedure that follows:

1. Remove plug (1) . The plug covers the adjustment pot on the rear of the annunciator module. Since moisture can be introduced into the ALM when the plug is removed, do this in a fairly dry environment. Remove this plug in an air conditioned area if relative humidity exceeds 60 percent.

2. Disconnect wires on terminals 1 and 7. Connect a variable DC power supply to the alarm module (+ voltage to terminal 1, - voltage to terminal 7). Set the power supply voltage to the desired set point for the low DCV alarm. The voltage must be between 8 and 38 volts.

3. Turn the adjustment pot fully clockwise.

4. After one minute, the low DC volts LED will flash. Press the acknowledge/silence switch to get a steady low voltage light.

5. Turn the adjustment pot counterclockwise slowly until the LED goes out.

6. Replace the plug.

7. Disconnect the variable DC power supply. Connect the wires that were removed in Step 2 .

SCM Speed Sensor Adjustment

Illustration 6	g00123218
Magnetic Pickup (1) Clearance dimension. (2) Locknut.

1. Remove the magnetic pickup from the engine flywheel housing and turn the flywheel until a gear tooth is directly in the center of the threaded opening for the magnetic pickup. Install the magnetic pickup again in the threads of the flywheel housing.

2. Turn (by hand) in a clockwise direction until the end of the magnetic pickup just makes contact with the gear tooth. Now turn the magnetic pickup back out 1/2 turn (180 degrees in the counterclockwise direction) in order to get the correct air gap (clearance dimension (1) ). Now tighten locknut (2) to a torque of 25 ± 5 N·m (18 ± 4 lb ft) .

   Note: Do NOT allow the magnetic pickup to turn while locknut (2) is tightened.

Temperature Sensor Resistance

Illustration 7	g00326429
Oil Temperature Sensor 1 Connectors (to pressure/temperature module).

The resistance value of the sensor corresponds to the surrounding temperature. This test will require that the sensor should be at room temperature.

1. Disconnect connectors (1) from the engine harness.

2. There is one electrical connection in each connector (1) . Measure the resistance between connectors (1) . Make sure that good contact is made between the connector pins.

3. Compare the measured resistance with that listed in the following chart.
   • If the resistance values do NOT agree, check connectors (1) and repair any defective connections. If connectors are okay, replace the coolant temperature sensor.

   • If the resistance values do agree, check the mating connectors at the pressure/temperature module. If connectors are okay, replace the pressure/temperature module.

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   Table 3

   Room Temperature	Resistance
   °C (°F)	ohms
   20 (68)	12,215 to 12,780
   21 (70)	11,680 to 12,215
   22 (72)	11,170 to 11,680
   23 (74)	10,685 to 11,170

SCM Verify Overspeed Switch

Illustration 8	g00326430
Back Of SCM (1) Overspeed verify switch.

The SCM will allow the service personnel to verify (check) that the engine overspeed protection is functioning. Actual overspeeding of the engine is NOT required. Activation of the overspeed verify switch will reduce the overspeed set point to 75 percent of the value that is programmed in the SCM. Therefore the overspeed verify speed is less than rated engine speed.

1. Operate the engine at rated speed. Monitor the gas shutoff valve and the ignition shutoff signal.

2. Press and hold overspeed verify switch (1) . Release the switch after the engine stops.

3. Check that the gas shutoff valve and the ignition shutoff signal caused the engine to shut down. Also, check that the overspeed LED on the SCM is flashing.

4. Turn the MCS to the OFF/RESET position.

SCM Verify High Oil Temperature Shutdown

This procedure enables service personnel to verify (check) that the engine high oil temperature protection is functioning. Substituting a variable resistor (potentiometer) for the temperature sensor will allow the testing of the circuit without overheating the engine.

Note: The low oil temperature alarm on the alarm module is tested in a similar procedure. However, (R) is replaced with a 20 000 ohm potentiometer.

Illustration 9	g00326431
High Oil Temperature Test Harness (C1) 7N-9737 Plug Housing . (C2) 7N-9738 Receptacle Housing . (R) 1000 ohm ten turn potentiometer.

1. Determine the set point for high oil temperature shutdown. Refer to "Programming The SCM" for further information on programming the SCM.

2. Turn the MCS to the OFF/RESET position.

3. Disconnect the two harness connectors at the temperature probe. Set (R) to 1000 ohms. Connect the test harness to the disconnected engine harness connectors.

4. Start the engine. Depress the display hold switch when the engine coolant temperature is displayed. The correct displayed temperature is approximately 88°C (190°F).

   Note: If equipped with an alarm module, the LED for high oil temperature and the horn on the alarm module are activated prior to engine shutdown.

5. Slowly adjust (R) until the displayed temperature is the same as the set point temperature (of Step 1 .

6. When the displayed and set point temperature are the same, the engine shuts down. Check that the gas shutoff valve caused the engine to shut down. Also, check that the LED for the high oil temperature on the SCM is flashing.

7. Turn the MCS to the OFF/RESET position.

SCM Verify Low Oil Pressure Shutdown

Illustration 10	g00326432
Low Oil Pressure Test Harness (A) Socket A of 8T-8730 Connector Socket . (B) Socket B of 8T-8730 Connector Socket . (C) Socket C of 8T-8730 Connector Socket . (R) Potentiometer, 1000 ohm, ten turn.

Note: Socket C of 8T-8730 Connector Socket (C) connects to the wiper of the potentiometer (R) .

This procedure enables service personnel to verify (check) that the low engine oil pressure protection is functioning. This procedure controls the oil pressure signal to the pressure/temperature module without affecting the engine lubrication system. Engine shutdown and alarm are verified at idle speed and rated speed.

Note: The LED for low oil pressure and the horn on an alarm module, if equipped, will activate at 34 kPa (5 psi) above the engine shutdown value.

Idle speed oil pressure shutdown occurs when the following conditions exist:

• Engine speed is less than the oil step speed value

• Engine oil pressure is less than the idle speed oil pressure shutdown value

Rated speed oil pressure shutdown occurs when the following conditions exist:

• Engine speed is greater than the oil step speed value

• Engine oil pressure is less than the rated speed oil pressure shutdown value

1. Determine the programmed SCM set point for: oil step speed, idle speed oil pressure shutdown and rated speed oil pressure shutdown.

2. Turn the MCS to the OFF/RESET position.

3. Disconnect the connector for the engine oil pressure sensor from the engine harness. Connect the test harness to the engine harness.

4. Turn the MCS to the AUTO position. Monitor the engine oil pressure on the SCM display. Adjust potentiometer (R) until the pressure that is displayed is greater than the idle speed oil pressure shutdown value, but less than 345 kPa (50 psi) .

   Note: The SCM displays an "09" dIAG code, when the sensed oil pressure is greater than 345 kPa (50 psi) and the engine is NOT running. If an "09" dIAG code is present, clear the code. To clear the diagnostic code, decrease the sensed oil pressure by adjusting potentiometer (R) . Turn the MCS switch to the OFF/RESET position.

5. Start and run the engine at idle speed. Keep the engine speed below the oil step speed set point.

6. Lower the oil pressure that is displayed on the SCM by slowly adjusting potentiometer (R) .

   Note: The engine shuts down when the oil pressure decreases below the set point for idle speed oil pressure shutdown.

7. Verify that the shutdown occurs when the displayed engine oil pressure is the same as (or slightly less than) the set point for idle speed oil pressure shutdown. Verify that the LED for the low oil pressure on the SCM is flashing.

   Note: The LED for the low oil pressure and the horn on an alarm module, if equipped, will activate prior to the engine shutdown.

8. Turn the MCS to the OFF/RESET position.

9. Turn the MCS to the AUTO position. Monitor the engine oil pressure on the SCM display. Adjust potentiometer (R) until the pressure that is displayed is greater than the rated speed oil pressure shutdown value, but less than 345 kPa (50 psi) .

   Note: The SCM displays an "09" dIAG code, when the sensed oil pressure is greater than 345 kPa (50 psi) and the engine is NOT running. If an "09" dIAG code is present, clear the code. To clear the diagnostic code, decrease the sensed oil pressure by adjusting potentiometer (R) . Turn the MCS switch to the OFF/RESET position.

10. Start and run the engine at rated speed. Keep the engine speed above the oil step speed set point.

11. Lower the oil pressure that is displayed on the SCM by slowly adjusting potentiometer (R) .

    Note: The engine shuts down when the oil pressure decreases below the set point for rated speed oil pressure shutdown.

12. Verify that shutdown occurs when the displayed engine oil pressure is the same as (or slightly less than) the set point for rated speed oil pressure shutdown. Verify that the LED for the low oil pressure on the SCM is flashing.

    Note: The LED for the low oil pressure and the horn on an alarm module, if equipped, will activate prior to engine shutdown.

13. Turn the MCS to the OFF/RESET position in order to clear the SCM.

14. Remove the test harness. Reconnect the engine oil pressure sensor to the engine harness.

Table 4

Gas Engine Status Control Panel Relay Logic Chart
Relay #	Function	Cranking	Crank Termination	Low Pressure Setpoint	Run	Fault Shutdown	Normal Shutdown Cooldown/Off	Comments
K1	2301 Ramp	D	D	E	E	D	E/D	Energized above Low Oil Pressure Setpoint.
K2	ENFR	D	D	D	D	E	D/D	Energized with Fault. Cleared with reset.
K3	CTR	D	E	E	E	D	E/D	Energized above Crank Termination RPM. De-energized at zero RPM plus 2 seconds.
K4	SMR	E	D	D	D	D	D/D	Energized to Crank. Locked out until engine stops and all Faults reset.
K5	RR	E	E	E	E	D	E/D	Energized whenever asking for engine to run. De-energized whenever asking for engine to Shutdown.
K6	MGR/MSR	E	E	E	E	E or D	E/E	Energized for normal operation if engine is being asked to start (ECS in Run or Auto with IC contact closed). De-energized for any emergency shutdown (see below). Contact will be re-energized 10 to 15 seconds after reaching zero RPM if engine is being asked to start.
K7	FCR-ETR	E	E	E	E	D	E/D	Energized to run. De-energized to Shutdown.

Emergency conditions are Overspeed; Emergency Stop Pushbutton; Diagnostic Codes 1, 4, 6; all six LEDs on

CTR - Crank Termination Relay

D - De-energized

E - Energized

ENFR - Engine Failure Relay

ETR - Energized To Run

FCR - Fuel Control Relay

MGR - Magneto Ground Relay

MSR - Magneto Shutdown Relay

RR - Run Relay

SMR - Starter Motor Relay

2301 Ramp - Woodward 2301 and 2301A Open Idle/Closed Rated Input

Restriction Of Air Inlet And Exhaust

There will be a reduction in the performance of the engine if there is a restriction in the air inlet system or the exhaust system.

The air flow through the air cleaner may have a restriction. The restriction must not be more than 3.74 kPa (15 inches of H₂ O) .

Back pressure is the difference in the pressure between the exhaust at the outlet elbow and the atmospheric air. Back pressure from the exhaust must not be more than 2.49 kPa (10 inches of H₂ O) .

Measurement Of Exhaust Temperatures

Illustration 11	g00286267
4C-6500 Digital Thermometer

Use the pyrometers on the panel for the Engine Supervisory System to check the temperatures at the cylinder heads. The 4C-6500 Digital Thermometer can also be used to check exhaust temperatures and coolant temperatures. The 4C-6500 Digital Thermometer can also be used to troubleshoot temperature problems that may not be integrated into the Engine Supervisory System. The Operators Manual, NEHS0554 is with the tool group and gives instructions for the test procedures.

Checking Aftercooler Operation

Illustration 12	g00286267
4C-6500 Digital Thermometer

Use the 4C-6500 Digital Thermometer to check the operation of the aftercooler. The Operators Manual, NEHS0554 is with the tool group and gives instructions for the test procedures.

Crankcase (Crankshaft Compartment) Pressure

Pistons or rings that have damage can be the cause of too much pressure in the crankcase. This condition will cause the engine to run rough. There will be more than the normal amount of fumes (blowby) coming from the crankcase breather. The breather can then become restricted in a very short time, causing oil leakage at gaskets and seals that would not normally have leakage. Other sources of blowby can be worn valve guides or turbocharger seal leakage.

Crankcase pressure is indicated on the panel for the Engine Supervisory System. If the crankcase pressure exceeds the system parameter, the Engine Supervisory System will shut down the engine. The 8T-2700 Blowby/Air Flow Indicator may be helpful in pinpointing the cause of the excess pressure.

Illustration 13	g00286269
8T-2700 Blowby/Air Flow Indicator

Compression

Engine compression problems can result in a variation of exhaust port head temperatures between cylinders. The panel for the Engine Supervisory System can be used to determine exhaust port temperatures. By performing a compression check, the condition of the following components can be tested:valves, valve seats, pistons, piston rings, and cylinder liners. If the exhaust port temperature from an individual cylinder varies by more than 40°C (104°F) from the average exhaust port temperature, then a compression check on the cylinder should be performed. Refer to Special Instruction, GMG00694 for instructions for the test procedure.

Ignition Group

Table 5

Tools Needed		Quantity
4C-4601 Spark Plug Socket		1
9U-7330 Multimeter		1

Spark Plugs

Voltage to cause the spark will change with the condition of the spark plug and the engine load. A new spark plug in an engine at low idle can require 3,000 to 6,000 volts to create an arc across the plug gap. At full load, this voltage will increase to 10,000 to 18,000 volts. As the spark plug wears, the gap will increase. Worn spark plugs can require over 30,000 volts to create an arc across the gap. Spark plugs will start to cause the engine to run rough (fire erratically) when the spark plug voltage requirements exceed 35,000 volts.

Poor maintenance of the spark plug can add a substantial cost to an operation over the service life of the engine. The following are some ways to improve the service life and the operating efficiency of the spark plugs that are being used on G3600 Engines.

• Use only the correct type of spark plugs.

• The spark plugs that are used in G3600 Engines are a single strap design with an adjustable gap. The gap on spark plugs should be set at 0.29 ± 0.04 mm (.011 ± .002 inch) .

• Always replace the spark plug gasket when a spark plug is removed and reinstalled.

• Spark plug resistance level measured between the center electrode and the extender connection point (top of spark plug) should be 6000 to 15000 ohms.

• Tighten the spark plugs in the cylinder head to a torque of 68 ± 4 N·m (50 ± 3 lb ft). DO NOT OVERTIGHTEN the spark plugs.

• The correct type of spark plugs have a precious metal coating. DO NOT use a wire brush to clean the tip of the spark plug.

• Do not use anti-seize compounds or allow oil or grease to remain on the threads of spark plugs during installation. Material that is placed or left on the spark plug threads and seat area will insulate the spark plug. This will prevent the transfer of heat to the cylinder head. If heat that is acquired by the spark plug cannot be transferred to the cylinder head, the spark plugs can be damaged by overheating.

• The air gap between the center electrode and the strap of the spark plug provides a resistance to the flow of electricity. That resistance is necessary to ensure that the correct voltage is available before the spark plug fires. Oil and/or grease on the spark plug can provide a path of less resistance. This will prevent the spark plug voltage from becoming high enough to arc across the plug gap. After cleaning or when installing new spark plugs, be careful to keep the spark plug and the extension surfaces clean.

Illustration 14	g00326433
Spark Plug Installation (1) High energy ignition transformer. (2) Tube. (3) Extension with spring loaded rod. (4) Spark plug.

Tighten connector nut to transformers, combustion buffers and magneto, clockwise, with 6V-0006 Governor Pliers until the nuts cannot be loosened by hand.

Illustration 15	g00326436
(5) High voltage terminal. (6) Transformer flange (ground).

Test the high voltage side of the transformer by measuring the resistance between the high voltage terminal (5) and the transformer flange (6) . The high voltage resistance is 5,000 to 12,000 ohms.

Test the low voltage side of transformer by measuring the resistance between "Pin A" and "Pin B" of the transformer. Low voltage resistance is 0.2 to 2.0 ohms.

Refer to Special Publication, NEHS0676, "Test Check Valves" for more information.

Cylinder Heads

The cylinder heads have valve seat inserts, valve guides, and bridge dowels that can be removed when the parts are worn or damaged. Refer to Disassembly And Assembly for the replacement of these components.

Valves

The removal and the installation of the valves is easier with use of the 1P-3527 Valve Spring Compressor .

Valve Seat Inserts

Use the 6V-4805 Valve Seat Extractor Tool Group for the removal and the installation of the valve seat inserts. Lower the temperature of the insert before the insert is installed in the head.

Valve Guides

The tools for the removal and the installation of the valve guides are the 5P-1729 Valve Guide Driver Bushing and the 7M-3975 Valve Guide Bushing Driver . The counterbore in the driver bushing installs the guide to the correct height. Use a 1P-7451 Valve Guide Honing Group in order to make a finished bore in the valve guide after the guide is installed in the head. Refer to Special Instruction, SMHS7526 for an explanation for this procedure. Grind the valves after the new valve guides are installed.

Checking Valve Guide Bores

Use the 5P-3536 Valve Guide Gauge Group in order to check the bore of the valve guides. Refer to Special Instruction, GMG02562 for the instructions for the use of this tool.

Illustration 16	g00285313
5P-3536 Valve Guide Gauge Group

Bridge Dowels

Use a 5P-0944 Dowel Puller Group and a 5P-0942 Dowel Extractor . Remove the bridge dowels. Install a new bridge dowel with a 6V-4009 Dowel Driver . This dowel driver installs the bridge dowel to the correct height.