The dual master cyliner was rebuilt and developed a problem of locking the rear brakes when the engine heated up. Run it in n the garage just sittinga and the brake lights go on. After three months of wating the master cyliner was replaced with a new unit from England. It still does it. Had it out yeaterday, drove 7 mile and all four wheels locked up tight. Let it cool down and all is fine. At this point all wheel cylinders have been replaced.

Submitted by bonnettoboot@e… on Mon, 03/08/2004 - 23:06

First ensure there is sufficient free play at the push rod going into the master cyl it should be 1 inch at the pedal. If it is ok then you have to check the operation of the one way valves at the inlet pipes, they are operated by the pistons closing when the cyl is pressurised and re opening as the pistons move back. If they do not re-open properly the fluid cannot be discharged, leading to a build up of pressure.

Jaguar affectionado and etc.