Bobcat T86 Loose Track and Tensioner Valve Leakage Diagnostic

Symptoms

• Visible sagging of the rubber track at the top rollers
• Grease pooling around the track frame access aperture
• De-tracking (track jump) off sprocket or front idler during pivot turn controls

Possible Causes

• Damaged or worn grease tensioner check-valve seat
• Ruptured internal high-pressure grease seal inside the tensioner cylinder
• Broken or fatigued heavy-recoil spring assembly inside the track frame

Diagnostic Procedure

1. 1
   Clean and Inspect External Grease Zerk Valve

   Locate the grease service opening on the track carriage. Clear mud away from the grease cylinder check valve. Pump grease to extend the tension cylinder. Wipe the zerk clean and watch for grease seeping backwards out of the port thread.
2. 2
   Measure Tension Cylinder Extension Drift

   Pump the track to Bobcat sag specification (approx. 15-20mm drop at center roller). Mark the polished cylinder shaft with a paint pen. Drive the loader forward/backward in sharp circles for 5 minutes. Measure if the cylinder shaft has retracted from the paint mark.
3. 3
   Check Cylinder Inner Seal Integrity

   Remove the inspection shield. Check high-pressure packing seals. Clean inside the track channel. If fresh grease is squeezing out of the outer seal cup directly onto the carriage frame, the inner high-pressure shaft seal ring is torn.
4. 4
   Inspect Recoil Spring Compression Frame

   Examine the heavy coil spring behind the tension cylinder. Check for fractures, severe rust-flaking, or foreign objects wedged in the spring pocket that prevent the recoil movement from protecting the tension seals.

Common Repairs

• Replacement of the track tension check valve cartridge
• Resealing the high-pressure tension cylinder
• Tracking frame recoil spring structural replacement

Safety Precautions

• Do not unscrew the tension grease valve more than 1 to 1.5 turns to bleed pressure; grease sits under dangerously high pressures.
• Keep hands away from track rollers and sprocket interface when tracks are suspended.

Required Tools

• Heavy-duty manual grease gun
• Calipers or steel tape measure
• 30mm socket for tension valves

Related Fault Codes

People Also Ask

• How do I measure and adjust track tension on a Bobcat T86?
• Why is grease leaking from my Bobcat track adjuster valve?
• How do you replace a leaking grease tensioner check valve on a Bobcat CTL?
• What causes a Bobcat rubber track to repeatedly jump off the sprocket?
• How do I determine if my Bobcat T86 track adjuster cylinder seals are blown?
• Can a failed recoil spring cause track tension loss on a Bobcat CTL?

Related Guides

Suggested Follow-Up Guides

• Bobcat T86 Track Tensioner Cylinder Rebuild and Seal Replacement Guide
• Bobcat CTL Recoil Spring Assembly Diagnostic and Safe Removal
• Bobcat T86 Drive Sprocket and Undercarriage Idler Wear Limits
• Rubber Track Replacement and Alignment Procedure for Bobcat T86 CTLs
• Heavy Equipment Grease Tensioner Valve Torque Specifications and Thread Repair

Topics

Related Repair Cases

Loading…

Community Comments