OVERHAUL

NOTE: This procedure requires a special piston cup installing tool MB990623–01 for 2-wheel drive Pick-ups and all Monteros, 4-wheel drive Pick-ups need MB 990621–01. A generous supply of DOT 3 brake fluid, alcohol or aerosol brake cleaner should be available for cleaning purposes.

1. Remove the wheel cylinder.
2. On either side, work the rubber boot off with a soft, blunt instrument such as a rounded piece of wood and then remove the piston.
3. Inspect the piston and cylinder walls for corrosion or scoring and replace parts that are defective. Check the clearance between the piston and cylinder wall. (Subtract the outer diameter of the piston from the inner diameter of the bore.) The limit is 0.006 in. (0.15mm). If clearance exceeds that value, replace the parts. Use inside and outside micrometers to make the measurements.
4. Clean all the parts with either brake cleaning spray or clean brake fluid. Clean the pistons and cylinder wall with DOT 3 brake fluid. If the piston/cylinder can be reused, replace the piston cup as follows:
   1. Work the cup off the end of the piston without causing damage.
   2. Apply the special grease included in the rebuild kit to the new piston cup and the special tool. If no grease is provided, use clean brake fluid.
   3. Set the piston on the workbench with one end up. Mount the special tool on top of the piston. Put the piston cup over the special tool with its lip facing upward.
   4. Slide the cup slowly and steadily down the special tool and into the groove of the piston. Be careful not to stop partway down! The idea is one smooth motion without stretching or ripping the cup.
   5. Repeat the operation for the other piston.
5. Coat the wheel cylinder bore and and piston cups either with the corrosion preventive agent contained in the repair kit or with clean brake fluid.
6. Carefully install the pistons into the wheel cylinder.
7. Apply the grease included in the repair kit to both of the piston ends and then install new rubber boots on both ends. Do not use other greases; the seals may be damaged.
8. Install the wheel cylinder.