Fault Phenomenon: Caterpillar D6N dozer difficult to start on cold mornings, starter motor turns but engine does not start.

Troubleshooting Process:
– Checked preheat system: some glow plugs failed.
– Checked fuel: fuel waxed or had water.
– Checked intake: air filter clogged.
– Checked cylinder compression: excessive valve clearance.

Root Cause: The winter fuel grade was incorrect, causing wax formation, combined with a poorly functioning preheat system, resulting in insufficient combustion chamber temperature.

Required Parts: Replace with winter-grade diesel and glow plugs.