Brakes binding after getting hot?

[Timi]

Hi I am a newbie,
I am on my second 200 tdi disco and I have a problem with my brakes.  When they get hot they appear to bind, after about  a half hour on the motorway they are bit hot and then the car starts to slow down to about 50mph so I have to change down to 4th just to keep it going at a reasonable rate.  
Sometimes when I stop and leave the vehicle for a while I loose all pressure on the brake pedal and it is very worrying.  Has anyone else had this problem.  I have recently changed both front calipers and this has not seemed to of helped, I believe I may have some water in the fluid which could be expanding when hot to cause the binding.
Is there any way I can tell if this is the only cause of this problem? or could it be a valve somewhere in the system which is not allowing pressure release back to the master cylinder?
Cheers
Timi  8)

[denviks]

wow now thats strange. i had a simialr thing happen to me on saturday. traveled down the motorway for about 15 miles. pulled in to a garage. got back in after using cash point. no preasure on the peddle. got out and felt wheels. hmmm front right was hot. got back in and pumped peddle. got preasure back . waited 10 secs and no preasure again. pumped i got it back again. 2 mins up the road they were back to normal.

it has me stumped....all i can think is dodgy fluid myself

[Xtremeteam]

what year of disco is it??
 from experiance the rear pads over time wear down through the rear caliper & then act like a lathe on the disc causing friction here & also if the rear psitons are stuck it will hold the brakes on,is it all the wheels that are hot after a run or is there a specific 1 that does it?
if some1 has got the pas & brake master mixed up & put the wrong fluid init it has that effect & wrecks all the seals in the system

you wont have "water" in the system,more like water vapour but this will cause the loss of pedal you describe after a journey as the brakes will be red hot

will have a think bout this
 8)

[denviks]

on mine its just the front drivers side wheel that is hot. i have had the wheel off and checked everything and all seems fine. no binding ect. looks hunky dory.  
confused the hell out of me thats for sure. i havent had a problem in 90 miles since saturday and that includes motorway work aswell. a mystery.  :roll:


edit: sorry mines a 200tdi 1993.

[Timi]

what year of disco is it??
 from  8)

It is a 91/92 J reg disco with 92/93 k reg front calipers and original rears, the front calipers were changed as the drivers side had two siezed pistons on the inside.  It seems as if all the brakes are binding after a run as they all smell hot! the brake fluid looked cloudy, but is turning darker due to the heat.  Any more suggestions?
thanks
Timi  8)

[Wanderer]

The first thing I'd do is check the calliper pistons are returning on their own and something isn't jamming them. Then change the fluid if you think it's been contaminated.

[Range Rover Blues]

You need to check that the pistons are moving when the brakes are applied and that's a 2 man job, one to watch and one to brake obviously.  You may have a wrecked master cylinder, ther's also a deceleration valve for the rear brakes but it's more likely to stay open than shut.  Oh yeah, check your flexis too, often a knacked one will have aflap inside that can work like a non-return valve or sometimes they collaps internally.  I've heard of both happening before now.

[muddysteve]

hello Tim  :D

[Sharpshooter]

Could also need a Brake Fluid change. Brake fluid actually attracts water, thats why you have a rubber seal on the pot cap. (aswell as to stop fluid coming out.

If the water content is too high (Local garage should be able to test for you), Then the water in the fluid heats up and expands. Brake fluid should not do this on its own.

Change all the fluid, and see if it still does it. I had it on my 205 GTI, and when it gets bad, you cant drive for more than a few mins before you notice it. :D

[Range Rover Blues]

If it's absorbed that much water then something is wrong!  It's the cheapest thing to try though so start there.

[Timi]

I have diagnosed the problem, water and air have been getting into the brake system due to the wrong ends being fitted on a replacement brake pipe.  
When removing the pipe the ends appeared to be rusty.  I have made a new pipe and changed the brake calipers on the back as well as the pressure relief valve and the master cylinder.  The amount of gunk that came out of the brake fluid we had it all black bits, grey bits, white bits, and brown bits.
There is nothing left to change and it appears to have worked.
I also found that the steering damper bushes had perished due to the slow drip drip dripping of engine oil.

I had a gorgeous assistant to pump the brake pedal which made the job easier.

Timi  8)

[hobbit]

Seeing as you have gone this far down this road, did you bleed through the sysytem completely and replaced with new fluid on all calipres?

[Timi]

Seeing as you have gone this far down this road, did you bleed through the sysytem completely and replaced with new fluid on all calipres?

Yes 1.5 litres of brake fluid! bled till it came clean and had no air in it!
Timi

[muddysteve]

He did indeed

Steve

ps i'm not the gorgeous assistant he's reffering to

[hobbit]

Thought you would, what rated fluid did you use?

[beast5680]

He did indeed

Steve

ps i'm not the gorgeous assistant he's reffering to

Really! :lol:  :lol:  :lol:  :lol:  :lol: