The backfill blade will not stay in position when tracking, swing, boom, stick, or bucket functions operate. Cylinder is fairly new. Trouble shooting to date: Extend cylinder all the way out. Take line off and plug line and install test line from open port to bucket. Shift cylinder to extend and no blow by fluid in bucket. Reverse the process to the other port and no blow by on retract. Based on that result the next item of intrest was the valve mounted in the cab. Replaced with new. Still have the problem. Any idea of the next step? Maybe the seals in the swivel?
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CAT 308E2 CR S/N FJX07459 blade droop
- Thread starter f311fr1
- Start date
Allan M
Well-Known Member
CAT 308E2 CR blade drop is most commonly caused by internal bypass or seal failure in the swivel joint (rotary manifold), particularly if it occurs while tracking. Other frequent causes include leaking blade lift cylinder seals, a faulty control valve, or contaminated hydraulic fluid.
Key Troubleshooting & Solutions
Key Troubleshooting & Solutions
- Swivel Joint/Rotary Manifold: If the blade drops, test by lifting it fully and checking if other functions (like the boom) try to move. A seal kit replacement or complete unit replacement is often required.
- Blade Cylinder: Inspect for worn seals or bent rods. Internal, damage to the cylinder can allow oil to bypass.
- Control Valve: Check for worn spools or contaminants holding the valve open.
- Operator Input: Ensure the joystick is not vibrating during tracking, causing the blade to lower.