Gast 1HAB-25 - Manual (Page 5)

Check that all external accessories such as relief
valves and gauges are attached to cover and are not
damaged before re-operating product.
If pump still does not produce proper vacuum or
pressure, send unit to a Gast Authorized Service Facility
for repair.
1. Disconnect electrical power to pump.
2. Disconnect air supply and vent all air lines to
release pressure or vacuum.
3. Remove the four Phillips-head screws in the shroud.
Remove the shroud.
4. Mark the position of the cylinder head to make
reinstalling easier.
5. Remove the four cap screws and washers from the
corners of the cylinder head. Remove the head.
6. Assemble the new gaskets, valves and valve plate
in the same order as the existing parts.
7. Remove the two cap screws and washers from the
cylinder. Remove the cylinder.
8. Remove the old piston seals, piston rings and piston
rider ring and discard.
9. Clean the cylinder head, valve plate and cylinder
with Gast AH255B solvent or other
non-petroleum based solvent.
Do not scratch or damage valve seal areas, gasket
seal areas or cylinder bore.
10. Inspect cylinder bore. If scoring has occurred, send
pump to a Gast Authorized Service Facility.
11. Install new piston seals, piston rings and piston rider
ring on the piston. The seal ring, joints should be
located opposite each other.
12. Slide the cylinder over the piston rings. Install the
two cylinder cap screws and washers and finger
tighten.
13. Rotate the pump so that the piston is at top and
center. Adjust the top of the cylinder so it is flush
with the top of the piston. Torque the cap screws to
150-160 in. lbs. Torque the bolts a second time.
14. Use the four cap screws and washers to install the
cylinder head, gaskets, valves and valve plate. (The
exhaust ports have a flat area on the center cooling
fins). Torque the cap screws to 110-120 in. lbs.
15. Operate the pump for approximately 10 minutes.
Torque the bolts a second time.