Radiator Cap: Testing and Inspection

Testing Cooling System Cap






Removing, Installing

NOTE: The cooling system cap in model 163 cannot be tested, it should be replaced if necessary.

1 Open cooling system cap (5, 5a)

NOTE:
- Cap (5, 5a)
- Cap with detent: carefully turn cap to the first detent, release pressure, and then unscrew cap.
- 2-stage cap: turn cap half a turn anticlockwise, release pressure, and then unscrew cap.

Testing cooling system cap with detent
2 Inspect cap (5) for corrosion

CAUTION: Replace if corrosion present.

3 Attach test cap (3) and double union (4) to tester (2)
4 Screw cap (5) with detent onto double union (4)
5 Test pressure relief valve
- Determine opening pressure of the cap (5) by pumping, replace cap (5) if necessary.

NOTE: As of 02/1986 the opening pressure of the cap has been increased from the previous 1.2 bar to 1.4 bar; consequently, the permissible coolant temperature is increased from 125 to 129 degrees C with standard antifreeze protection down to -30 degrees C.

6 Test vacuum valve (6)
- If cap (5) fitted: the vacuum valve (6) should be resting against the rubber seal (arrow), it can be raised easily and springs back when released.

Testing 2-stage cap
7 Attach test cap (3a) to tester (2)
8 Screw on 2-stage cap (5a) at test cap (3a)
9 Test pressure relief valve
- Determine opening pressure of the cap (5a) by pumping, replace cap (5a) if necessary.

10 Install in the reverse order.