4.5 UNIT TROUBLESHOOTING - continued.
TEST OR INSPECTION
2. Unisex defueling coupling leaks at coupling inlet.
Disconnect coupling from inlet. Replace inlet O-ring (paragraph 4.8).
3. Unisex defueling coupling leaks at filter sump boss.
Step 1. Check coupling security.
Make sure coupling is secure by attempting to tighten. Do not over-tighten.
Step 2. Repair defueling unisex coupling assembly (paragraph 4.8).
4. Leak at sight gauge.
Inspect gauge body for physical damage.
Repair sight gauge (paragraph 4.12).
5. Leak at filter vessel cover.
Step 1. Check mounting bolt security.
Verify that all twelve bolts are torqued to 30 ft lbs.
Step 2. Replace filter vessel cover O-ring (paragraph 4.6).
6. Differential pressure gauge does not operate.
Step 1. Check for blockage.
a. Drain filter vessel into a suitable container.
b. Remove hard lines connected to the differential pressure gauge and inlet and outlet ports. Blow through
lines to verify that lines are not blocked with sediment. Clean or replace lines if blocked (paragraph
4.11). If lines are open, replace differential pressure gauge (paragraph 4.11).