C5 X7 - excessive heating on all 4 brakes

[dme88]

After a short drive, all my brake discs are very hot. Brake pads in the front was replaced 4 months ago, and the rear 14 months ago.

The heat is uniform, altho there is slightly more heat on the rear left disc. The discs now have 2-3 groves in them.

Could this be the master cylinder?

Car coast fine in N, so no excessive braking is felt while driving

[411514]

Could this be the master cylinder?

Could be, particularly if the binding gets worse and worse as temperatures increase - i've had that a few times before. But master cylinder don't usually fail like that in operation - usually that happens immediately after having some work done on the brakes, e.g. pads.

But how hot are we talking? Too hot to touch the discs after more than a 5 min run is fairly normal. But obviously smoking/radiating excessive heat isn't.

Are the brakes binding at all when cool/have you jacked up and turned wheels by hand.

[lexi]

Your pads may be sticking. I would strip off pads and file and lube them till you can flick them with a screwdriver when all done up and see movement of both pads. When they stick and are not noticed they can destroy the pads, discs and caliper seals with heat.

[centurus2400]

If the back brakes are binding it's almost certainly a fault with the handbrake mechanism in the rear callipers. They can get very sticky to the extent they won't wind back.
I've now had both of mine replaced which has cured the problem completely and given me a noticeable improvement in fuel consumption!

[dme88]

@411514

Yeah, this hot. Maybe it's normal? Front pads are fairly new(<1000km)

[petarc1971]

You may be using the brakes too much. The wheels can be slightly heated so that the hand can be held, hotter than that is not good. All 4 wheels should be removed and the condition of the main pistons and guide pistons should be inspected - this was to be done by a mechanic when he was working.