Bobcat T770 DPF Regeneration Incomplete, Low Engine Power

Confirmed cause: A small, hard-to-see crack was found in the plastic fuel return line originating from the aftertreatment fuel dosing module. The crack was located where the line passed through a retaining clip on the engine block. The line was wet with diesel, but there was no active drip onto the ground, making it difficult to spot. Repair performed: Replaced the cracked aftertreatment fuel return line. Cleaned the surrounding area to ensure no other leaks were present. Changed the engine oil and filter due to fuel contamination. Verification: Initiated a stationary DPF regeneration. Monitored exhaust temperatures, which now climbed quickly to the target range. The regeneration cycle completed successfully in the normal amount of time. The engine power was restored, and the related fault codes cleared. Technician notes: - The high and fuel-contaminated oil level was a key early clue. The un-burned fuel from the leaking return circuit was seeping past the rings and accumulating in the crankcase. - The fuel leak was minor and did not affect engine performance directly, only the aftertreatment system, which delayed diagnosis. - Always check the entire length of aftertreatment fuel lines, especially at any clamp or routing points where vibration can cause chafing or stress fractures.