Caterpillar G3500 — Ignition System Spark Plugs - Check/Adjust/Replace
Maintenance
For the Caterpillar G3500, from the Caterpillar owner's manual.
Applies to: Caterpillar G3500 engine
Before you start
- Ignition systems can cause electrical shocks; avoid contacting ignition system components and wiring during operation.
- Do not overtighten spark plugs - can crack shell/deform gasket.
Procedure
- Remove the spark plug
- Inspect the spark plug for deposits and damage
- Clean the spark plug using glass beads (do not use a wire brush)
- Measure spark plug resistance with the 142-5055 Insulation Testing Group; discard if resistance exceeds specification (~1000 ohms for 146-2588, ~500 ohms for 194-8518)
- Set electrode gap using the 9U-7516 Spark Plug Gauge: 0.29 ± 0.03 mm (0.011 ± 0.001 in) for compression ratio >9:1, or 0.35 ± 0.03 mm (0.014 ± 0.001 in) for compression ratio ≤9:1
- Install a new 9Y-6792 Spark Plug Gasket if reinstalling a used spark plug
- Install spark plug by hand until it bottoms out, then tighten to 68 ± 4 N·m (50 ± 3 lb ft)
- Lubricate O-ring seal with dielectric grease or silicone lubricant, install transformer and connect wiring harness
- Install the valve cover
Tools required
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- Spark plug torque 68 ± 4 N·m (50 ± 3 lb ft)
- Electrode gap per compression ratio (see steps)
Source: Caterpillar owner's manual. Steps and values are as documented; always cross-check against the official manual and any later revisions for your exact serial number before servicing.