Caterpillar 320 L

Pull engine and hydraulic oil samples at every 500-hour service on the 3066 (or 3116 on later PIN blocks) and track trends, not single readings. Watch standby pump pressure and cycle times as a proxy for pump regulator and destroke solenoid wear, a common cause of stalling and bogging under load, not the engine itself. Log final drive and swing drive oil condition at every change; metal in either signals face-seal wear starting before it reaches a leak.

No-power and stalling complaints on the 320L most often trace to the hydraulic pump regulator or destroke solenoid sticking in a high-flow position and overloading the 3066, not to fuel or injection faults. Check pump standby pressure before chasing the engine. The 3066 uses ether starting-fluid injection for cold starts, not glow plugs; hard cold starting means a weak or empty ether canister, not a glow-plug relay. Monitor-panel and gauge wiring corrosion is common on machines stored outside; clean and reseal connectors at the Action Lamp circuit before swapping gauges.

Final drive and swing motor face seals define a 320L rebuild: packed undercarriage debris pushes the seal out of alignment, gear oil leaks out, and gear teeth, coupler splines, and bearings wear fast once lubrication drops. Catch it at the leak stage, not the lockup stage. On the hydraulic side, inspect the pump and main control valve once standby pressure or cycle times drift, since the 320L's hydraulic system runs both off one circuit. Swing bearing bolt torque and gear backlash are the checkpoints before a full swing-drive rebuild.

Confirm the ether starting-aid canister is full and the solenoid fires before every cold season; the 3066 has no glow plugs, so this is the engine's only cold-start assist. Wash undercarriage and final drive housings after work in mud, clay, or demolition debris. Packed material against the sprocket is what drives face-seal failure on this chassis. In hot or dusty applications, shorten the 250-hour engine oil interval and clean radiator and oil cooler fins often. Check coolant corrosion-inhibitor level year-round; these are conventional-coolant-era machines, not ELC-filled from the factory.