Possible Cause: Air in cylinder - bleed cylinder using following procedure.

• Raise the dump body and cylinder to full extension.
• Lower the dump body and cylinder till the front of the dump body is approximately 2 feet off of the chassis frame.
• Put the body up lever in the hold position (center).
• If you have an outside bleeder valve, crack the valve open at this time.
• Wait until all trapped air has escaped from the valve and a full stream of hydraulic oil is escaping from the valve.
• At this point the cylinder is bled, close the bleeder valve.

If your bleeder valve is located on top of the cylinder you will need a 9/16" wrench to remove the dog box cover and you will need to move to the inside of the dump body.

• Remove the dog box cover and crack the bleeder valve open at this time.
• Wait until all trapped air has escaped from the valve and a full stream of hydraulic oil is escaping from the valve.
• At this point the cylinder is bled, close the bleeder valve.

Possible Cause: Air in the hydraulic cylinder.

• See procedures to bleed air out of the cylinder in "Cylinder operation is jerky or cylinder slow coming down" above.

Possible Cause: Head nut too tight on one of the cylinder stages.

• Identify stage that is hanging up.
• Back head nut off 1 full turn, then re-tighten 3/4 turn.

Possible Cause: Dump truck is being operated with the body up lever unlocked in the down position.

• The body up levers (cable actuated) must be manually locked into the center position with every use, they are not self locking.
• The body up lever not being centered is the most common problem with excessive air in the hydraulic system.

Possible Cause: Oil level in hydraulic tank is low and suction hose is sucking air out of tank.

• Top off hydraulic tank with hydraulic oil.

Possible Cause: Cylinder head nut needs tightening (normal maintenance item)

• Refer to dump body owner's manual, cylinder section.

Possible Cause: Bleeder valve left open at the top of the cylinder.

• Remove the dog box cover inside the dump body with a 9/16" wrench and tighten the bleeder valve.

Possible Cause: Cylinder wiper or packing protruding above head-nut.

• Call J&J Warranty Dept. (800.777.2671) with the dump body serial number and discontinue use of cylinder.

Cylinder seems loose or rattles in the dog house

Possible Cause: We receive many calls on what appears to be loose cylinders.

• A telescopic cylinder mounted to a dump body and chassis frame needs a certain amount of play so the cylinder does not destroy itself when operated in motion or slightly off level. This play in the cylinder is normal.
• If after further analysis, the operator detects a problem outside of the above explanation, please call the Warranty Dept. at J&J Truck Bodies (800.777.2671)

Cylinder drifting down in hold position

Possible Cause: (See Cab Controls)

Possible Cause: (See PTO's and Pumps)

Possible Cause: Body up cable may have been impacted from underneath damaging either cable or cable connection to the pump. This may result in pump spool being unable to return to center.

• Inspect cable and connection kit.
• If damaged, replace damaged components.
• Call 800-777-2671 and ask for the Parts Department. (Body serial number needed)