Hi All,

Following on from the above post I didn't use the car over the Christmas period . In the New Year I checked the booster was working, by pressing my foot on the brake pedal before starting the engine then feeling the foot pedal go down under the same pressure, which it did. After that the pedal seemed to engage the brakes a bit lower down the travel. I used it on short journeys for a few weeks but on 25th Jan the brakes started to drag again. I called the garage and they couldn't fit it in until 8 Feb. They now reckon it may be the non-return valve on the pipe from the inlet manifold to the booster. My understanding is this valve is fitted to maintain a vaccum in the booster for a short period of time in the event of an engine failure. I can't think why this valve being faulty would cause brake drag with the engine running. They told me it wasn't expensive and was what a Jag engineer told them may be the cause.
Would appreciate anyone's thoughts on this.

Kind regards

Jim

 

Get brakes super hot and once you stop it immediately put a hose of the brake bleeder valve on one wheel open the bleeder see how much fluid comes out you’ll find out where the pressure is being blocked or pumped from. So it’s either the master cylinder, pushing brake fluid onto the pedal the antilock brake module, stuck calipers or an internally collapsed line that is acting like a one-way valve causing it. . If you get it super hot and then measure the motor fluid that comes out of one brake, you’ll be able to calculate the volume in the line. Maybe measure the temps on all four brake calipers and see if they re all similar or if one is way worse. Maybe measure the pressure at the master cylinder. Measure the vacuum at the booster. Heck disconnect it and see if it happens. Something will tell what it is or could be or couldnt be the cause. Narrow down WHY and where or what could do it then check. See if one brake drags. Something will show you something