Brake hydraulic fluid should be changed on a regular basis in accordance with the vehicle's routine maintenance schedule. The procedures for changing the brake fluid and bleeding the hydraulic system are very close in order of execution, taking into account the points noted in the text.
The hydraulic circuit of the brake system is equipped with several bleed valves. So, valves are available on brake calipers and wheel cylinders. In addition, some models are equipped with an additional bleed valve installed on the pressure regulator valve.
1. Fill the reservoir on the GTZ with clean brake fluid and keep it at least half full during the entire bleeding procedure.
Note. If it is necessary to change the brake fluid, drain it from the reservoir, wipe the inner walls of the latter with a clean, lint-free rag and fill with fresh fluid.
2. Connect a piece of transparent hose to the left rear bleed valve (on wheel cylinder) or to the valve valve - pressure regulator (if equipped). Lower the opposite end of the hose into a transparent container partially filled with clean brake fluid.
3. Depress the brake pedal several times, lock it in the lower position and turn off the valve. Tighten the valve and slowly release the pedal. Repeat the procedure until liquid free from air bubbles begins to come out of the hose.
Note. If fluid has been changed, continue pumping until clean, fresh fluid comes out of the hose.
Attention! In order to avoid re-entry of air into the system, do not allow the brake fluid in the GTZ reservoir to drop below half the level during pumping, periodically top up. The fluid drained from the system cannot be reused - use only fresh fluid for topping up.
4. Repeat procedures for remaining bleed valves.
5. After pumping is completed, the brake pedal should be depressed with firm resistance without any signs of softness. Check the tightness of all bleed valves.
6. Add the required amount of fresh brake fluid to the GTZ reservoir, bringing its level back to normal.