xm brakes

crooser · Post by **crooser** » 29 Oct 2004, 01:49

this problem may also apply to xantias.almost immediately after switching off the engine of my xm i find that i have no brakes. does anyone have any ideas?

406 V6 · Post by **406 V6** » 29 Oct 2004, 02:58

pressure accumulator sphere is flat, that's why with no pump feeding the pressure with engine off, the brakes are gone.

alexx · Post by **alexx** » 29 Oct 2004, 03:55

Anyway, rear brakes should work for some time after switching the engine off, even with flat accu sphere, because they are connected to rear suspension

jeremy · Post by **jeremy** » 29 Oct 2004, 03:59

The rear brakes may not do very much if the car is lightly laden although I would have thought that this problem wasn't so pronounced on a car as heavy as an XM. Its perfectly possible that the rear calipers/pistons are seized and require overhaul or replacement.
I entirely agree that the reason the front crakes don't work is an accumulator problem.
Jeremy

crooser · Post by **crooser** » 29 Oct 2004, 11:10

thanks men but what is the cure?

Post by **RichardW** » 29 Oct 2004, 12:44

>thanks men but what is the cure?
Fit a new accumulator!! It's the sphere down the front of the engine. If you listen to your car whilst its idling, you'll probably find it ticks every couple of seconds - this should be more like a minute. Plenty of posts on here how to change spheres, and only about £20 from GSF.

NiSk · Post by **NiSk** » 29 Oct 2004, 13:01

Judging from your collection of XM's, the job can be anything from fairly easy (XM 2.0 VSX) to a nightmare for a contortionist (XM 2.5 TD).
With the petrol engined car (as long as you don't have A/C fitted) its easy to find the accumulator sphere (also applies to TD12 without A/C) - it's located on the front of the gearbox right up close to the engine joint. Its in the same place on the 2.5 TD - it's just completely hidden by all the charge air hoses, the fuel filter/water seperator, water/air intercooler and some cooling water hoses.
Actually removing the sphere is much easier if you have a proper sphere removal tool - there isn't much room to swing a tool down there. I got the sphere off my TD12 with the help of a blunt chisel and sledge hammer - hitting it at a tangent on the equatorial weld seem (rotate it anti-closkwise to remove).
BUT before you do all that, put the car on ramps, select lowest (service ) height, and unscrew the pressure relief valve on the pressure regulator (thats the metal block the sphere is mounted on) A HALF TURN ONLY (its the only 12mm bolt on the front of the regulator).
//NiSk

crooser · Post by **crooser** » 29 Oct 2004, 14:39

thanks NiSK,it's the 2.5 that i am going to do,the 2.0 is now just for body spares.i know where the acc' sphere is and how awkward the job will be.a previous reply mentioned frequent ticking but i hardly ever hear any ticking,suspension and brakes are fine with engine running and no sinking when stopped.i presume this means that it is still the acc sphere.

ItDontGo · Post by **ItDontGo** » 29 Oct 2004, 14:59

Could also be a leaky component draining the acc sphere down a return line constantly. Obviously one would change the sphere as a first course of action.

crooser · Post by **crooser** » 29 Oct 2004, 21:39

Itdontgo,if your reply is correct,do you think that this could cause less than perfect brakes?there is no air in the system and no wheel cylinders are sticking,also there are no external fluid leaks.