Remove road dirt and grease from the exterior of the compressor with a cleaning solvent. Before the compressor is disassembled, the following items should be marked to show their relationship when the compressor is assembled. Mark the rear end cover in relation to the crankcase. Mark the cylinder head in relation to the crankcase. Mark the base plate or base adapter in relation to the crankcase.
A convenient method to indicate the above relationship is to use a metal scribe to mark the parts with numbers or lines. Do not use a marking method that can be wiped off or obliterated during rebuilding, such as chalk. Remove all compressor attachments which have not been previously specified.
Cylinder Head Disassembly
Remove the four cylinder head cap screws and tap the head with a soft mallet to break the gasket seal. Scrape off any gasket material from the cylinder head and crankcase.
Before disassembling the discharge valve mechanism, measure and record the discharge valve travel (from closed to completely open).
1. If the measured discharge valve travel DOES NOT EXCEED 0.8128 mm (.032 in), the discharge valve stop need not be removed. It is recommended that the cylinder head body be replaced if the discharge valve stop requires replacement. In the event this is not possible the following procedure can be followed: Using a 9/16 hex wrench, remove the discharge valve seat, valve, and valve spring.
To remove the discharge valve stop, support the machined surface of the cylinder head on an arbor press bed and gently press the stop from the top of the head and out the bottom. Be sure to allow sufficient clearance for the stop between the press bed and the bottom of the cylinder head. The valve stop bore in the cylinder head must be inspected for excessive scoring. A new cylinder head body must be used if scoring is excessive.
2. Remove the unloader stop and O-ring.
3. Remove the unloader piston and O-ring.
4. Insert the lugs of a spanner wrench into the holes of the inlet valve stop and remove the inlet valve stop along with the inlet valve, valve seat, unloader gasket and spring. (NOTE: Reference Williams adjustable face spanner #483).
5. Inspect the unloader piston bushing for nicks, wear, corrosion and scoring. It is recommended that the cylinder head body be replaced if it is determined that the unloader piston bushing requires replacement. If this is not possible, the bushing can be pressed out of the head using the same procedure presented in Step 2 of this disassembly section.
NOTE: If the bushing is pressed out and the cylinder head casting is damaged in the process, cylinder head repair is not recommended. Pressing in the replacement bushing will result in air or water leakage.
Crankcase Base Plate Or Adapter Disassembly
1. Remove the cap screws securing the base plate or base adapter. Tap with soft mallet to break the gasket seal. Scrape off any gasket material from crankcase and plate or adapter.
Connecting Rod Disassembly
Before removing the connecting rod, mark the connecting rod and its cap. The connecting rod is matched to its own cap for proper fit, and the cap must be reinstalled in the same position on the rod.
1. Straighten the prongs of the connecting rod bolt locks and remove the bolts and bearing cap.
2. Push the piston with the connecting rod attached out the top of the cylinder of the crankcase. Replace the bearing cap on the connecting rod.
3. Remove the piston rings from the piston. If the piston is to be removed from the connecting rod, remove the wrist pin teflon plugs and press the wrist pin from the piston and connecting rod.
4. If the piston is removed from the rod, inspect the wrist pin bore or the bronze wrist pin bushing in the connecting rod. If excessive wear is noted or suspected, replace the connecting rod.
Compressor Crankcase Disassembly
1. Remove the key or keys from the crankshaft and any burrs from the crankshaft where the key or keys were removed.
NOTE: Through drive compressors may have a crankshaft key at both ends.
2. Remove the four cap screws and lockwashers or nuts and lockwashers that secure the rear end cover to the crankcase.
3. Remove the rear end cover, thrust bearing and end cover O-ring taking care not to damage the bearing if present in the end cover.
4. If the compressor has ball type main bearings, press the crankshaft and ball bearings from the crankcase, then press the ball bearings from the crankshaft.
5. Press the oil seal out of the compressor crankcase if so equipped.