Master Cylinder Inspection Procedure

Suspect master cylinders can be identified by visual inspection as follows:

1. Inspect the master cylinder for a white paint dab on its forward nose. A cylinder with a white paint dab on the nose is OK and no further service is required. If there is no white paint marking, go to step 2.

Note:
Cars cleared at the factory were marked on the nose of the master cylinder, not the flange as described in the referenced electronic mail instructions. Flange paint markings already made by dealers to show service completion per those instructions are also acceptable. No further service is needed in either case.

2. Inspect for date code. The date code is stamped on the top of the master cylinder flange which is fastened (two nuts) to the vacuum booster attaching studs. It is located above the left (drivers side) attaching stud hole. The code appears as shown below:

XXXX (4 digit part number code is not important)

7335A (7 is year 1987 -- 335 is 3 digit date code -- A is shift).

Only the 3 digit date code is important:

A. If date code is 335 or higher, cylinder is OK and no further service is required. Apply a dab of white paint to the nose of the master cylinder to indicate service completion.
B. If date code is lower than 335, perform the following brake system test.