Kohler 38RCL manual Ignition System, Model Spark plug gap 38 RCL, 48RCL, and 60RCL

4.7 Ignition System

Service the spark plugs at the interval specified in the service schedule using the following procedure.

1.Press the OFF button on the RDC2 controller.

2.Disconnect the power to the battery charger.

3.Disconnect the generator set engine starting battery, negative (--) lead first.

4.Remove spark plug wires by grasping the spark plug boot and turning slightly while pulling. Do not pull the wire. Pulling on the wire rather than the boot may damage the wire or terminal.

5.Loosen the spark plug with a ratchet and 5/8-in. spark plug socket with a rubber insert to prevent spark plug damage.

6.Use compressed air to remove dirt from around each spark plug to prevent dirt particles from falling into the combustion chamber.

7.Remove spark plugs, one at a time, and examine. Identify a normal spark plug in good operating condition by observing a light tan or gray deposit on firing tip. See Figure 4-9 to evaluate engine condition by color/condition of a problem spark plug.

8.Clean spark plugs by wiping them with a rag. File the center electrode to keep it parallel to the side electrode.

Note: Do not sandblast, wire brush, scrape, or otherwise service spark plugs in poor condition. Obtain a new plug for best results.

9.Check the spark plug gap before installing any spark plug. See Figure 4-7 and Figure 4-8. Attain a correct gap when the feeler (or wire) passes between the spark plug electrode. It should pass easily but with some resistance or drag; otherwise adjust as necessary.

Model	Spark plug gap
38 RCL, 48RCL, and 60RCL	0.9 mm (0.035 in.)

Figure 4-7Recommended Spark Plug Gap

	1
	2
	1-514
1.	0.9 mm (0.035 in.) gap
2.	Spark plug electrodes

Figure 4-8Spark Plug Gap Inspection

Problem/Condition	Means of Identification	Possible Cause/Solution
Gap-bridged spark	Built-up deposits and gap between electrodes	Oil or carbon fouling. Clean and regap the spark
plug	closing.	plug.
Oil-fouled spark plug	Wet, black deposits on the insulator shell, bore,	Excessive oil entering combustion chamber
	and electrodes.	through worn rings and pistons, excessive
		clearance between valve guides and stems, or
		worn or loose bearings. Replace the spark plug.
Carbon-fouled spark	Black, dry, fluffy carbon deposits on insulator	Incorrect spark plug, weak ignition, clogged air
plug	tips, exposed shell surfaces and electrodes.	intake, overrich fuel mixture, or excessive
		no-load operation. Clean and regap the spark
		plug.
Lead-fouled spark plug	Dark gray, black, yellow, or tan deposits; or a	Caused by highly leaded fuel. Replace the
	glazed coating on the insulator tip.	spark plug.
Pre-ignition damaged	Melted electrodes and possibly blistered	Wrong type of fuel, incorrect timing or advance,
spark plug	insulator. Metallic deposits on insulator suggest	too hot a plug, burned valves, or engine
	internal engine damage.	overheating. Replace the spark plug.
Overheated spark plug	White or light gray insulator with small black or	Engine overheating, wrong type of fuel, loose
	gray/brown spots with bluish (burned)	spark plugs, too hot a plug, low fuel pressure or
	appearance on electrodes.	incorrect ignition timing. Replace the spark plug.
Worn spark plug	Severely eroded or worn electrodes.	Caused by normal wear and failure to replace
		spark plug at prescribed interval. Replace the
		spark plug.

Figure 4-9Engine Evaluation Using Spark Plug Condition

TP-6810 11/13 Section 4 Scheduled Maintenance 53