my wife was driving home in our 94 4x4townace.put the brakes on and the pedal was rock hard and didnt stop.i replaced the alternator about two months earlier.i got the ace home and put a new master cylinder on and they work fine.until you pump them and they go hard again.but work very little. if you leave them alone for a few secs they work.someone help please.

- (#3229) tony, 2 Jun 02

On the earlier diesel vehicles, the vacuum pump, neccessary for power braking, is mounted on the alternator drive. Is yours a diesel and, if it is, is there a failure on the vacuum pipework from the pump unit ? Alternatively, are the calipers, or the guide rods, on the front disc brakes, seizing, possibly due to corrosion on the brake cylinders or guide rods ? The brake pedal may go quite hard but, with little or no brake effort on the discs.

- (#3231) John Davis, 2 Jun 02