PEUGEOT 504 Series 1970 Workshop Manual page 468

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Q.
BRAKES
CHECKING A SERVO-UNIT
IV · CHECKING FOR AIR LEAKS
WARNING· This
check must only be carried
out after
checking of the fluid system (see instructions for
pressure checking).
- Free the servo-unit (five applications of the brake
pedal engine at rest.
- Install pedal depressor.
- Turn the knurled nut (a) until the slots
(b)
are
closed-off.
- Start the engine :
the pedal should descend, and
· hydraulic pressure increase.
- Re·t1ghten the knurled nut (a) until slots (b) are
just closed-off.
- Line-up the two needles of the H.P. gauge (c).
- Stop the engine.
- One minute later the indicated pressurP. should not
be less than :
· 504 RH drive · 290 p.s.i. (20 bars)
· 504 LH drive · 362 p.s.i. (25 bars).
If the fall in pressure is excessive.
- Fit a new
valve
(1) and new seal (2).
- Repeat the tests, if the fall is pressure is still
excessive the servo-unit is suspect.
Ref. 1212 · E.