Greasing Pivot Points on CAT D4C II Requires Identifying True Lubrication Ports and Avoiding Machining Marks

[MikePhua]

CAT D4C II Dozer Overview and Historical Context
The Caterpillar D4C II is a compact crawler dozer introduced in the early 1990s, designed for grading, site preparation, and light earthmoving. As part of the D4 series, it features a torque converter transmission, mechanical steering clutches, and a hydraulically controlled blade system. Caterpillar, founded in 1925, has long been a leader in track-type tractors, and the D4C II represents a transitional model between purely mechanical machines and more electronically integrated systems.
The D4C II is especially popular among small contractors and landowners due to its manageable size, reliability, and straightforward maintenance. With an operating weight of around 17,000 pounds and a 75-horsepower diesel engine, it offers enough power for most grading tasks without the complexity of larger machines.
Identifying Grease Points vs Machining Ports
One of the most common maintenance tasks on the D4C II is greasing the pivot points on the blade and lift arms. However, confusion often arises when operators encounter ports that appear to be grease fittings but lack threaded zerks. These are often mistaken for missing fittings, but in reality, they may be machining reference points used during factory assembly or cylinder alignment.
A true grease fitting, or zerk, is a threaded port designed to accept a grease gun nozzle and allow lubricant to flow into a bearing or bushing. Machining marks, on the other hand, are smooth, untapped holes that serve no lubrication function. Attempting to force grease into these can damage the surrounding metal or waste time during service.
Confirmed Grease Points on the Blade Assembly
On the D4C II, the blade typically has four primary grease points:

• Two at the C-frame pivot pins, where the frame connects to the crossbar
  
• Two at the tilt cylinder ends, which allow the blade to angle laterally
  

These points are fitted with standard zerks and should be greased every 50–100 operating hours, depending on usage and environmental conditions. In dusty or wet environments, more frequent greasing is recommended to flush out contaminants.
Greasing Technique and Equipment
To properly grease the D4C II:

• Use a high-pressure grease gun with a flexible hose for tight access
  
• Select NLGI Grade 2 lithium-based grease with molybdenum disulfide for high-load joints
  
• Clean the zerk before connecting the gun to avoid injecting dirt
  
• Pump until fresh grease appears at the joint edges or purge ports
  
• Wipe off excess to prevent attracting debris
  

If a zerk is missing or broken, it should be replaced immediately. Threaded holes can be cleaned with a tap and fitted with a new zerk. If the hole is untapped and smooth, it is likely not a grease point and should be left alone.
Maintenance Tips and Common Mistakes

• Do not assume every port is a grease fitting—verify before applying pressure
  
• Avoid over-greasing, which can rupture seals or create hydraulic lock
  
• Keep a maintenance log to track greasing intervals and zerk replacements
  
• Inspect pivot points for wear or play during greasing to catch early failures
  

One operator shared a story of mistakenly trying to grease a machining port on the lift arm, only to find no resistance and no grease flow. After consulting a service manual, he discovered the actual grease points were located on the opposite side of the cylinder. This highlights the importance of documentation and visual confirmation.
Conclusion
Greasing the pivot points on a CAT D4C II dozer is a vital part of routine maintenance, but it requires accurate identification of true lubrication ports. Misinterpreting machining marks as grease fittings can lead to wasted effort and potential damage. By focusing on the confirmed grease points and using proper technique, operators can ensure smooth blade operation and extend the life of critical joints. For new owners, investing in an official operation and maintenance manual is a smart move that pays dividends in uptime and reliability.