From Failure Cleanup to Continuous Contamination Control: How GRS Restored Reliability to a CAT D8R Transmission

When a CAT D8R dozer experienced a transmission failure, repairing the damaged component was only part of the challenge. Metal contamination from the failure had circulated throughout the transmission system, creating a significant risk to the newly repaired components.

Simply replacing parts would not eliminate the contamination left behind. To help restore system cleanliness and reduce the risk of future wear, the customer partnered with Guardian Reliability Services to perform a complete contamination cleanup and implement a long-term filtration solution.

The Challenge: Residual Contamination Threatening a Repaired Transmission

Transmission failures often generate a large volume of metallic debris that remains suspended throughout the oil system long after repairs are completed.

This CAT D8R faced several contamination-related concerns:
• Metal debris distributed throughout the transmission oil
• Increased risk of accelerated wear on repaired components
• Potential for contamination-related secondary failures
• Lack of continuous filtration to maintain long-term cleanliness

Without removing the contamination, the repaired transmission could continue operating in an environment that promotes premature component wear and reduced reliability.

What GRS Delivered: Filtration, Oil Polishing, and Long-Term Protection

Guardian Reliability Services implemented a comprehensive contamination control strategy designed not only to clean the system but also to help keep it clean.

1. Complete Oil Removal and Replacement
The contaminated transmission oil was drained and replaced with fresh 30W transmission oil, creating a clean baseline for the restoration process.

2. Permanent Auxilary Kidney-Loop Filtration Installation
GRS installed a permanent auxiliary kidney-loop filtration system to continuously remove contamination independent of the machine’s primary filtration system.

3. Mobile Oil Polishing Services
Using GRS’s mobile oil polishing equipment, technicians connected directly to both transmission cases, which shared a common oil supply, allowing contaminants to be removed throughout the entire system.

4. Continuous Cleanliness Monitoring
Throughout the oil polishing process, fluid cleanliness levels were routinely monitored to verify contamination removal and ensure cleanup targets were achieved.

The Results: A 128x Reduction in Contamination

The contamination reduction achieved during the project was substantial.

Starting ISO Cleanliness: 22/20/18
Final ISO Cleanliness: 15/13/10

This represented a 7-code reduction across the 4μm, 6μm, and 14μm particle ranges.

Because each ISO cleanliness code represents approximately a doubling or halving of particle concentration, a seven-code improvement equates to roughly a 128-times reduction in particle concentration within those measured ranges.

The result was a dramatically cleaner transmission system and a significantly improved operating environment for critical components.

The Long-Term Value: Keeping Oil Clean, Not Just Cleaning It Once

While the immediate cleanup was important, the greatest benefit came from the installation of the permanent auxiliary filtration system.

With continuous kidney-loop filtration now operating on the transmission, the customer gained:
• Improved protection of critical transmission components
• Reduced abrasive wear caused by particulate contamination
• Earlier detection of contamination-related issues through oil analysis
• Longer potential component life
• Greater confidence following a major repair event
• A measurable, proactive reliability strategy centered on oil cleanliness

Instead of treating cleanliness as a one-time maintenance activity, the operation now has a system designed to manage contamination continuously.

A Question for Your Operation

After a major component failure, how confident are you that contamination has been completely removed from the system?

Replacing damaged components is important, but protecting those components from the contamination left behind is what helps ensure long-term reliability.

If contamination is impacting the performance or lifespan of your hydraulic, lubrication, fuel, or transmission systems, Guardian Reliability Services can help you implement a filtration strategy that supports cleaner fluids, longer component life, and improved reliability.

22/20/18 → 15/13/10

The numbers tell the story. Clean oil isn’t just about the oil. It’s about protecting your equipment, your maintenance investment, and your operation.