172-65254M-03 (A-COS-10) 27 Oct 2008
14
Disassembling the Pilot Section
The diaphragm is removed by utilizing the notch in the pilot body. Loosen the pilot
valve seat with a box wrench and remove it. Lift the pilot valve spring up and out with
a pair of tweezers. Then loosen and remove the screen holder to remove the screen.
Check for any fault on the seat of the pilot valve, flaws on the gaskets, and clogging
of the screen.
Check for deformation, corrosion or faults on the diaphragm. The diaphragm should
be convex (open downward), with the printed UP mark on the top.
Disassembling the Piston
Remove the pilot body after loosening and removing the hex bolts (stud bolts).
During this process, pay attention not to lose the connecting tubes (2).
Remove the piston and the cylinder from the body. Then remove the piston rings and
the tension rings from the piston. Do not apply too much force when removing the
piston rings and tension rings.
Inspect the interior of the cylinder, the exterior of the piston rings, the small hole on
the piston and the gasket for any fault or abnormality.
Diaphragm
Pilot Valve Seat
& Gasket
Pilot Valve
Pilot Valve Spring
Pilot Valve
Body
Notch
Pilot Screen
Pilot Screen Holder
& Gasket
Hex Bolt
Gasket
Piston Ring
Tension Ring
Cylinder & Gasket
Gasket
Piston
Connecting Tubes
Hex Bolt
Piston Ring
Tension Ring