10-10-20 Recommendations for Gas Engine Spark Plug

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Engine News 2010/10/20 Media Number -SEBD9674-00

Publication Publication Date -20/10/2010 -20/10/2010

Date Updated -20/10/2010

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Recommendations for Gas Engine Spark Plugs {1550, 1555} SMCS - 1550; 1555 Caterpillar Products: G3300 Family Generator Sets G3400 Family Generator Sets G3500 Family Generator Sets and Power Modules Engine: Commercial G3400 Family G3500 Family Engine: All G3600 G300 Family G3300 Family

Engine News SEBD9500, 7 February 2007, "Recommended Spark Plugs". Disregard the old article. Recommendations have been enhanced and part numbers have been changed and added. Refer to the information below.

Introduction In order to ensure the maximum performance fo r Caterpillar Gas Engines, always use the correct spark plug. Failure to follow this recommendation can result in less than optimum engine performance and in reduced service life of the spark plug. Table 1 lists the recommended spark plugs for current Caterpillar Gas Engines. Table 1 Engine

Description

Serial Number

Recommended Spark Plug


G3300

G3304 and G3306 Std plug

G3300

G3304 and G3306 Canadian Standard Association (CSA)

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S/N:37Y, 07Y

2N-2839 Spark Plug 108-3515 Spark Plug Gasket

S/N:37Y, 07Y

4W-2256 Spark Plug 176-7748 Spark Plug Gasket

S/N:4FD, 1RK, 5NW, CTS, 6NB, 7DB, CTP (1)

2N-2839 Spark Plug 108-3515 Spark Plug Gasket

S/N:4FD, 1RK, 5NW, CTS, 6NB, 7DB, CTP (1)

4W-2256 Spark Plug 176-7748 Spark Plug Gasket

S/N:6RJ, BAZ, 3WR, 6FW, 3NK, 6ZM, 8LW, CTP (2)

104-3170 Spark Plug 108-3515 Spark Plug Gasket

G3406 Std plug for 9.4:1 and 10.3:1

G3400

G3408 Std plug for 9.4:1 and 10.3:1 G3412 Std plug for 8.5:1, 9.7:1, and 11.4:1 G3406 CSA for 9.4:1 and 10.3:1

G3400

G3408 CSA for 9.4:1 and 10.3:1 G3412 CSA for 8.5:1, 9.7:1, and 11.4:1 G3408 Std plug for 11.4:1 G3408C Std plug for 11.4:1

G3400 G3412 Std plug for 11.4:1 G3412C Std plug for 11.4:1


G3408C Std plug for 8.5:1 G3400

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S/N:BAZ, 3WR, 6FW, 6ZM, 8LW, CTP (2)

G3412C Std plug for 8.5:1

128-6238 Spark Plug 108-3515 Spark Plug Gasket

G3500

G3500 Std plug for all Magneto, EIS, and ADEM III

S/N:2JF, 4KC, 3RC, 4WD, 5JD, 8LD, 9TG, 7NJ, 4EK, 5PN, 9AW, 6JW, 8PW, 2TJ, 9FP, 5ZZ, 8JZ, 7SZ, 8BZ, GET

194-8518 Spark Plug 9Y-6792 Spark Plug Gasket

G3500

G3500 EIS

S/N:4WD, 5JD, 8LD, 9TG, 7NJ, 4EK, 5PN, 9AW, 6JW, 8PW, 2TJ, 9FP, 5ZZ, 8JZ, 7SZ, 8BZ

224-2700 Spark Plug 9Y-6792 Spark Plug Gasket

G3500

G3500B and G3500C

S/N:7EZ, CEY, CTW, CSC, CME, CFD, CTK, BGW, GAS, GSB, GZA, GZB, GZC, 346-5123 Spark Plug GZG, GZH, GZL, GZM, GZN, GZP, GZZ, 9Y-6792 Spark Plug GWD, CWD, CWW, CWY, B9P, GHC, Gasket GHE, HEB, ZBB, ZBC, TJB, TJC, SLY, RLP, HAL, SXY

G3600

All G3600 Natural Gas

S/N:3XF, 4WF, 1YG, 4CG, 4ZS, BEN, BKE, BLB

G3500c and G3600

G3500c and all G3600 S/N:3XF, 4WF, 1YG, 4CG, 4ZS, BEN, Bio-Gas BKE, BLB, MAD, HAT, GZK, GZJ, LGS (Landfill Gas and Digester Gas)

(1)

For CTP equipped with the Caterpillar Digital Ignition System (CDIS)

(2)

For CTP equipped with Electronic Ignition System (EIS)

301-6663 Spark Plug 9Y-6792 Spark Plug Gasket 243-4291 Spark Plug 9Y-6792 Spark Plug Gasket

Spark Plug Tools Table 2 Part Number and Description 4C-4601 Spark Plug Socket

Use

Size

Remove and install spark plug (18 mm)

177.8 mm (7/8 inch Hex)

9S-5031 Socket

Remove and install combustion sensor

127mm (5/8 inch Hex)

216-1685 Socket - Spark Plug

Remove and install spark plug (18 mm)

330.2 mm (13/16 inch)


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154-9521 Spark Plug Seat Cleaner

Seat cleaner

14 mm (0.551 inch Thread/Seat Cleaner)

9U-7511 Spark Plug Seat Cleaner

Seat cleaner

18 mm (0.709 inch Thread/Seat Cleaner)

Spark Plug Life Spark plugs operate in severe conditions. Spark plugs require regular maintenance to provide desired engine performance. The service life of a spark plug is directly related to the voltage required to produce a spark in the electrode gap. As the voltage required to produce a spark increases, the service interval is reduced and the overall service life decreases. Higher voltage reduces the service life of components such as spark plugs, wires, and transformers. The following six main factors affect the vo ltage required for spark plugs: Air-fuel ratio - When the air-fuel ratio is near stoichiometric, the voltage required to produce a spark is the lowest. As the air-fuel ratio becomes leaner, the voltage required becomes higher. Compression ratio - As compression pressure increases, the required voltage increases. Ignition timing - As ignition timing is retarded, the voltage required to produce a spark will increase. Electrode wear - As the spark plug electrode wears and becomes more rounded, the voltage required to produce a spark will increase. Fuel BTU - Lower BTU fuel reduces the spark plug service life. Electrode gap - The wider the spark plug gap, the more voltage is needed to produce a spark.

All of the factors above, except for compression, can be adjusted somewhat on most gas engines. As compression increases, the required voltage increases. A cleaned and regapped plug requires more voltage than a new plug. As the gap increases on a plug the voltage required for spark increases dramatically. The required voltage can exceed the arc over voltage of the plug. Arc over voltage is the amount of voltage required to produce a spark between the electrode and the ground strap. Fuels that cause high levels of deposits can cause compression to rise well beyond normal. Higher compression increases the voltage required closer to the arc over voltage. The service life of the spark plug varies for different applications. The service life can be affected by various factors and operating conditions. To help predict the spark plug service life for G3500 and G3600 engines, use Caterpillar Electronic Technician (ET) to monitor the "Cylinder #X Transformer Secondary O utput Voltage Percentage" parameter. The value of this parameter will increase over time. Experience at the particular site will help to determine the proper interval for replacement of the spark plugs. If a diagnostic code is generated for the ignition transformer secondary circuit, the spark p lug may need replacement. Misfire and a cold cylinder are other indications of a worn spark plug. Use Cat ET to monitor the exhaust port temperatures in order to loca te a cold cylinder.


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Recommended Maintenance of Spark Plugs Spark Plug Removal • Remove a spark plug by hand after the initial torque is broken. • If the spark plug resists removal by hand, apply penetrating oil to the threads. To help the oil penetrate the threads, turn the spark plug back and forth until the spark plug is loose. • If the spark plug could not be removed by hand, clean the threads with a spark plug seat cleaner. Part numbers are listed in Table 2. The seat cleaner scrapes debris from the seat and from the threads in the cylinder head. Be sure to remove any debris from the cylinder.

Spark Plug Gasket • After removing the spark plug, remove the compressible metal spark plug gasket. • Always install a new spark plug gasket when installing or reinstalling a spark plug. • Orient the tabs of the gasket toward the spark plug electrode. Otherwise, the gasket may not seat properly. • If a gasket for a spark plug is installed incorrectly, do not increase the torque on the spark plug in order to improve the seal.

Spark Plug Installation • Always regap the spark plug when the spark plug has been removed. • Always use a new gasket when installing the spark plug. • Install the spark plug into the seat by hand. If the spark plug cannot be seated by hand, there is a problem with the threads. • Always finish installing a spark plug with a torque wrench and spark plug socket.

Recommended Maintenance Practices for Spark Plugs with Adjustable Electrodes Inspection Note: Normal operation will produce a light ash deposit on the portion of the plug exposed to combustion. Heavy ash deposits are a sign of poor combustion or high oil consumption. Clean such deposits from the plug.

• Inspect the spark plugs closely to look for damage and/or to determine if the ignition system is operating correctly.


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• Check the entire plug for mechanical damage, such as cracked insulators or metal cases. If any cracks are found, replace the plug. • Faint marks may extend from the top edge of the metal case onto the insulator. The marks may be the result of corona that forms at the top of the metal case. Corona develops when a high voltage potential ionizes the air that surrounds a conductor. The marks are a normal condition. The marks are not a result of leakage between the metal case and the insulator. Many times these marks are misinterpreted as combustion leaks and the plugs are discarded with many more service hours available. • Look for eroded electrodes. An eroded plug is a worn out plug. Spark plugs in this condition will require more voltage to produce a spark. A worn plug can require more voltage than the ignition system can supply.

Spark Plug Cleaning • Solvents can be used to clean oil and tar deposits from all plug surfaces with no adverse affects on the plug. • When used with caution, glass beads can be used to clean the combustion end of the spark plug. Apply the glass beading only to the electrode area of the spark plug. Do not apply glass beads to the case or to the threads. Clean the threads with solvent and a clean wipe. Do not reuse the glass beads. • Always keep the ignition components clean and free of dirt and oil.

Recommended Maintenance Practices for Spark Plugs with Pre -combustion Chambers Inspection Note: A spark plug can operate despite a buildup of ash. Large deposits may retain heat that can cause premature fuel ignition. Large deposits can lead to uncontrollable detonation.

• Inspect the spark plug pre-combustion chamber for deposits. • Make sure that the holes in the spark plug pre-combustion chamber are not blocked. • A light brown deposit or a beige deposit is produced by normal operation. Deposits that are gray or black may be caused by the following conditions: excessive oil, use of the wrong oil, a substance that is introduced through the fuel system or the air system and poor combustion because of a rich air/fuel mixture. • Condensation can form in spark plugs that have pre-combustion chambers. Condensation can cause difficulty for cold start-ups. If an engine shuts down during the warm-up cycle, condensation can form. The condensation can cause start-up difficulty until the condensation evaporates or until the plugs are changed. Engine block heaters will help avoid this situation.


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Spark Plug Cleaning Do not clean and reuse spark plugs with pre-combustion chambers. If the buildup of ash is considerable, change the plug.

Maintenance and Installation Practices to Avoid Maintenance Note: If you change all of the spark plugs from J-gap plugs to plugs with pre-combustion chambers, the air fuel ratio may need adjustment. The engine can be run leaner with plugs that have precombustion chambers.

• Do not clean the spark plug with a wire brush. Deposits of brass on ceramic can cause the spark plug to short circuit. • Do not use a thread tap to clean spark plug threads in the head. A tap is designed to remove metal. This practice will eventually result in thread failure in the cylinder head. • Do not mix types of transformers in an engine. • Do not mix types of spark plugs in an engine. • Do not mix spark plugs with pre-combustion chambers and J-gap spark plugs in the same engine.

Installation • Do not use anti-seize compound on spark plugs. Most of the heat is transferred through the threads and the seat area of the spark plug. Contact of the metal surfaces must be maintained in order to provide the heat transfer that is required. • If a gasket for a spark plug is installed incorrectly, do not increase the torque on the spark plug in order to improve the seal. • Do not over tighten a spark plug. Over tightening the spark plug can cause cracks. Over tightening can also yield the metal, which loosens the shell. Discard any spark plug that has a shell that is cracked or loose. Copyright 1993 - 2011 Caterpillar Inc. All Rights Reserved. Private Network For SIS Licensees.

Mon May 16 13:51:50 EST 2011

10-10-20 Recommendations for Gas Engine Spark Plug

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