MAINTENANCE
®SULLAIR®
3700 Operator’s Manual and Parts List
35
AIR FILTER ELEMENT REPLACEMENT
1. Clean exterior of air filter housing.
2. Rotate end cover counterclockwise and remove
3. Remove air filter element by pulling it out of the 
housing.
4. Clean interior of housing using a damp cloth. DO 
NOT blow dirt out with compressed air.
5. At this time replace the element.
6. Reassemble in the reverse order of the disassembly.
6.8 SEPARATOR MAINTENANCE 
Replace the separator element when indicated by the 
microprocessor or after one (1) year, whichever comes 
first. The separator element must be replaced. DO NOT 
attempt to clean the separator element.
SEPARATOR ELEMENT REPLACEMENT
Refer to Figure 6-3. The separator element must be 
changed when indicated by the microprocessor, or once 
a year, whichever occurs first. Follow the procedure 
explained below for separator element replacement.
1. Loosen and remove the eight (8) hex head 
capscrews (5/8 x 2") from the cover plate.
2. Lift the cover plate from the sump. 
3. Remove the separator element.
4. Inspect the receiver/sump tank for rust, dirt, etc.
5. Reinsert the separator element into the sump taking 
care not to dent the element against the tank 
opening.
6. Install a new O-ring in the O-ring groove on the 
underside of the receiver/sump tank cover.
7. Replace the cover plate, washers and capscrews. 
Torque to 55 ft•lbs. (75 Nm).
8. Clean the return line strainer before restarting the 
compressor.
 Figure 6-3
1. Cover
2. Ground Spring*
3. Spring Fastener*
4. Cover Gasket*
5. Element*
6. Sump Tank
* Replacement Kit P/N 02250160-774
F i g u r e   6 - 3        
Separator Element (P/N 02250160-776)
OIL RETURN/SIGHT GLASS MAINTENANCE
Refer to Figure 6-4. The oil return/sight glass 
subassembly is attached to the side of the separator 
tank. Oil return/sight glass maintenance should be 
performed on a routine basis parallel to that of the fluid 
filter, or as indicated in the troubleshooting section of this 
manual. The maintenance on an oil return/sight glass is 
mainly concerned with the condition of the filter 
assembly. Order filter assembly No. 02250117-782, and 
use the following instructions as a guide.
NOTE
Relieve all pressure from the sump tank 
and all compressor lines.
SU_0000038
NOTE
Always perform maintenance on both oil 
return/sight glasses at the same time.
SU_0000039