Brakes Pressure

28cer · February 13, 2008

just bought a is200 ran fine for 3 months but now the front brakes lock on after 5 min of driving, changed both front calipers but the problem is still there on the front 2 wheels. the guy who i bought the car of had the same problem and had the master cylinder changed which curred it for 5 months. the abs kicks in aswell all the time, but as soon as you bleed any of the calipers it runs fine for 5 min and then pressure builds up and the brake pedal goes hard? please help

ROYT · February 13, 2008

Wild guesses....the piston in the master cylinder is not returning far enough, maybe pedal needs adjusting.

This may cause the brake servo to be slightly on, slowly applying the brakes.

Cannot guess at the ABS involvement in this!

sparkystav · February 13, 2008

Without much knowledge on it, it does sound like the abs.

Doesnt the abs pump fluid in and release when needed so if its valves were passing it'd be pushing fluid in?

Stav

28cer · February 13, 2008

Without much knowledge on it, it does sound like the abs.
Doesnt the abs pump fluid in and release when needed so if its valves were passing it'd be pushing fluid in?

Stav

thanks thats what i thought but need someone to confirm this for me. Is there someone in manchester that could look at it for me? not a dealership

sparkystav · February 14, 2008

Gords mate Steve is in Glossop at charlesworth motors?

he's a good mechanic with lots of Lex experience.

Stav

Jack300 · February 14, 2008

...brake servo? I'm out of my depth here but dosn't the servo help apply pressure (via hydraluic fluid) to the brakes? What if the servo thinks that the pedal is being pushed? ...could be the brake master cylinder having a rubber seal mounted the wrong way around... What if the brake servo non-return valve (works on a vacumn dosn't it) is failing - just made that up but it sounds right.

Not making this up. Wife's Saab brakes have always been grim. After 3 yeras it fails it's MOT on a rear handbrake not working. It's siezed. I freed it off and adjusted both back hand brake mechs at the same time (didn't know it has them) and what happens - all of the breaks now work great - front included. So, problems with the front brakes, look to the back brakes for the solution...

Good luck

jack