18.7. Removal of air from hydraulic system of coupling

Prevention

The brake fluid used in hydraulic system of coupling is poisonous therefore at its hit on skin it is necessary to wash out immediately this place a plentiful amount of water. If liquid got into eyes or in an organism, it is necessary to see a doctor immediately. Some liquids have property to ignite easily and can light up even from contact with hot knots of the car. Besides, the liquid used in hydraulic system of coupling dissolves paint and plastic therefore at hit of liquid on a paint and varnish covering of the car wash out it a plentiful amount of water. Also this liquid is hygroscopic, i.e. absorbs moisture from air and therefore the liquid which is stored a long time in open ware is not recommended to be used.

For removal of air from hydraulic system of coupling Mercedes-Benz recommends to use the special equipment which gives the chance to delete air under pressure.

Any hydraulic system works normally and reliably if air is removed from hydraulic liquid in system.

During removal of air add only pure liquid of the required type. Never reuse liquid which flowed out from hydraulic system of coupling.

If in hydraulic system incidentally there was a mixing of liquids of various types, remove liquid from hydraulic system, wash out system pure liquid of the required type and establish new sealing rings.

At continuous leak of liquid from hydraulic system or hit in hydraulic system of air define the reason and the place of leak and eliminate damage.

Installation of a tube (1) on the pumping union (2) workers of the cylinder of coupling

PERFORMANCE ORDER
1. Lift a forward part of the car and record on supports.
2. Remove an engine mudguard.
3. Check connection of a hydraulic tube and hose of coupling are reliably tightened, and the pumping union on a back part of the working cylinder of coupling is screwed up. Remove a dustproof cap from the union of pumping and clear all traces of dirt about the union.
4. For removal of air from hydraulic system it is necessary to use the special equipment working from the external pressure (the beefy camera of a spare wheel). After connection of the tight camera with liquid to a popolnitelny tank of the brake system removal of air consists in plum of liquid via the pumping union on the working cylinder of coupling until the following liquid does not come out without vials of air.
5. When using this method with a big tank with liquid additional protection of hydraulic system of coupling against possible hit of air is provided during pumping.
6. Dress a transparent hose on the pumping union which second end lower in the glass vessel which is partially filled with brake fluid (see the drawing).
7. According to the instruction connect the device for removal of air under pressure to a popolnitelny tank of the brake system.
8. Unscrew the pumping union on a half of a turn and allow liquid to flow down in a glass vessel until it does not leave without vials of air.
9. After removal of air from гидравличес which systems of coupling screw up the pumping union, remove from it a hose and remove adaptation from a popolnitelny tank.
10. Clear the pumping union of brake fluid and establish on it a dustproof cap.
11. Check the level of brake fluid in a popolnitelny tank and, if necessary, add brake fluid.
12. Check smoothness of the course of a pedal of coupling. If when pressing the pedal of coupling moves with breakthroughs, so at hydraulic system of coupling there is an air. If after repeated removal of air the coupling pedal moves unevenly again, so sealing rings of the main or working cylinder of coupling are worn-out.
13. Lower the car.