Is it my Master Cylinder or just a gremlin eating parts?

I have a disco 200tdi. A few months ago the following happened. When driving for over 20 mins or so (when she got hot) everytime the breaks were usesd got a little stiffer and so on untill I was struggling in 1st to even move from a standstill... this happenening on the motorway was not good. Stop a few mins.. kick the wheels, she's fine again for another 20 mins or so.

It stopped happening on and off.. guess was a new master brake cylinder.. 2 months ago.. after a few weeks the same started happening.. finally it happened yesterday again.. Get in car brake drops to floor.. ten minutes later.. brakes are stiffer than Gary Glitter in Thailand... and locking on just as hard with no presure on the pedal.

Tried to bleed/flush everything last night, yet not even a squirt when trying to bleed it through.. result - another brake cylinder to be purchased tonight..

Is it me or does this seem rather dodgy? Anyone got any ideas? Or was I just bloody unlucky to et through 2 in as many months?

It may be relevant.. doesnt seem to be any leaks from anywhere, the resevoir was always a good happy level.. although the fluid did go a very concerning colour... might be my fault, as when we put a new cylinder (re con) on last time we just poured the old fluid from the resevoir back in (I know I know.. should have used new) Did suck out the fluid in the reseviour a few weeks ago and topped with fresh.. went nasty colour again.

Yeh, the fluid went a sort of dark colour.. like there was drops of oil in it, buit not.. if that makes sense..

Erm ok, better way to describe it...

It looked like it was full of shi*, but you know when you get little drops of water in oil.. and it floats.. well it looked like that in the resevoiur, not much just a little browny scummy dropletty layer on the top of the fluid (which incidentally was a drity blacky brown colour)

first thought is water in the fluid - wot happens then is that on use , the water can boil and lock the system up. but that is usually with heavy use - best to flush the complete system tho as a start. It obviously int rite.

Thats what I thought... when boils.. locks sytem.. when cools, leave a "gap" so no pressure.. But where the hell is it coming from? And how come it has killed another cylinder so quickly? Theres a big bottle of fresh fluid waiting to go in the new.. hang on.. the new NEW cylinder and sytem.. but I dont want to have to put this on for it to stary dying in another few weeks!! I dont mind the occasional costs.. but new cylinder every 1500 miles.. not to mention the diesel of having to "drive through" the brakes when they lock on!!

It has been said "he drives it like he stole it" so it may* get a bit of heavy braking.. but not often, it usually only does 50/60 miles in the week.

Drive it and put the back of your hand to each wheel to see which ones getting hot. Sounds like you've got a seized piston in one of the calipers.

I thought of that, but they all get f**king hot. So far have had the front two wheels off, but gonna change the wheels round at the same time (back/front) to get the most out of them.. is there a quick way to tell if its a psiton problem when the wheels are off.. (would this in turn kill the cylinder.. cos the most recent one (few months old) is most definately now naffed.

(Dads the engineer, I merely try to diagnose the problem as Im the driver and ask him to do the grubby work)

I may even have the pads off as well, im thinking after the last 3/4 months with the brakes putting themselves on (even if only gently at times) has probably* worn them a tad.

(But still wondering how the water got in in the first place???, thinking the gremlin may be using the sytem for relieving itself)

Should have brought jap... Mitsi's never have these problems I bet...

doug84 said:

Should have brought jap... Mitsi's never have these problems I bet...

Click to expand...

Aye yer cud of done but look at what a new cylinder would cost.

Ok ok.. but Landy bits are only cheaper cos they sell so many as they go wrong!!!!!

But hey ho, thats part of the fun isnt it.. who wants a car that just works all the time.. wheres the fun eh!?

Had a similar problem in a transit once. Brakes locked solid at Hyde Park Corner 5.30 on a Friday. We put the flashers on, pulled out a seat and sat behind it smoking waiting for the AA and the idiots STILL came up behind and hooted. It was poor adjustment on the master cylinder wot caused it, but I don't know if the same can apply on the disco.

Seems to me if your brakes are coming on as you drive that on its own will heat them up and boil the fluid.

That would make sense... well I'll see how father does it this time.. maybe a pot of fresh fluid will make the difference this time and a New new cylinder.. not a sparkly clean re-con one this time.