i'm new to the forum and have a 02 x type. is there an easy way to tell if the brake booster is bad or if there is a leak elsewhere? when the brakes are first applied while driving they work as normal but if you let up on the pedal as slowing to a light and then press again, its like there is no power assist. I have a new vacuum line to the booster.

 

Seems like nobody is answering you so here we go. If there is a problem with your brakes you should get it to a tech as this is a crucial system for your safety. That being said, you said you already replaced the vacuum line for the brake booster. This line is a very common leak point (specifically at the one way valve in the line). The other points where there would be a leak would be the seals that the line attaches to. Assuming the car's never been on an accident the booster is not likely to go bad, I'm a Jaguar mechanic and I never replaced one, although is possible. There is not quick way to check for leaks in the brake booster, but if there was such a leak you would have a check engine light as this is a vacuum leak. To check for proper operation of the brake booster:

1) Pump the brake with the engine off until the pedal is hard
2) Pressing on the pedal Turn on the engine
3) The pedal should go down (to have an idea of how this should feel you can do this test on another car first)

Also the problem you describe doesn't necesarily mean the brake booster:
What kind of pads do you have?
What kind of rotors? Did you ever changed the rotors?
What kind of brake fluid?

I wish you good luck and if you can give me more info maybe we can figure it out. And BTW I wrote an article on how to change the front brakes on your car if you wanted to take a look... here is the link:

Changing the front brakes on a Jaguar X-Type (2001 - 2005)

 

Nice, simple diagnostic test, daxter.

 

thanks, i'll check when i get home today.

 

Good post Dax

The booster isn't likely to be the problem IMHO. More likely your pads are shot or your brake fluid is still the original fluid and now is water contaminated to the point that it is no longer properly effective. If you start to lose your brakes after a lot of braking, likely the fluid is boiling.

A vac leak somewhere else in the system may also be a culprit.

 

The next step would be to change your brake fluid, I recomend this one specifically, it does wonders

Motul Brake fluid DOT 5.1

 

Motul is good stuff. Prefer ATE Super Blue myself but either would be a good choice.

 

Hi there not sure if I need a brake booster but brakes are very hard like I do not have power assist if i pull the vacuum line from the engine it runs rough front brakes were done but had problem before i did the brakes

 

Pump the brake with the car OFF until is hard. Then step on the brake and while applying pressure turn the engine on. You should feel your foot go down. If you don't then you most likely have a brake booster problem.

This test I just told you do it first on a buddy's car so you get a feel of what you are looking for, then do it on your jag, most brake boosters work under the same principle.

Best of luck and let us know the happy ending!!!!!