S 600 Coupe (140.076) V12-6.0L (120.982) (1997)
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:
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Cap (5, 5a)
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Cap with detent: carefully turn cap to the first detent, release pressure, and then unscrew cap.
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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
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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)
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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
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Determine opening pressure of the cap (5a) by pumping, replace cap (5a) if necessary.
10
Install in the reverse order.