arghh - Pug 205 GTi brake failure....
Discussion
Hi all,
Had a 'moment' this morning, lost all pressure in the brakes on my 1.9. Fortunately managed to coast to a stop. Anyone experienced this and if so, what r the likely causes?
I'd had a bit of a blat just before hand so they'll have been quite hot, have I knackered the fluid? Any thoughts and pointers greatly appreciated!
j
Had a 'moment' this morning, lost all pressure in the brakes on my 1.9. Fortunately managed to coast to a stop. Anyone experienced this and if so, what r the likely causes?
I'd had a bit of a blat just before hand so they'll have been quite hot, have I knackered the fluid? Any thoughts and pointers greatly appreciated!
j
What are/were the symptoms?
Did your pedal drop to the floor?
Did it go "spongy"?
Did your brakes simply not stop you when you pressed the pedal?
Did your brakes return to working after a while?
Have you checked your brake fluid since?
Answer a few of these and we'll have a better idea
Did your pedal drop to the floor?
Did it go "spongy"?
Did your brakes simply not stop you when you pressed the pedal?
Did your brakes return to working after a while?
Have you checked your brake fluid since?
Answer a few of these and we'll have a better idea
Sorry - should have been more specific.
I noticed the pedal felt spongy when just covering the brakes in moving traffic (30-40ish) then soon after I needed to come to acomplete stop to turn off, the pedal had some resistance but went completely to the floor, only applying a small amount of force. It would build up pressure if I pumped it but only briefly. I can't see any leaks and the fluid level's good but the master cylinder looks decidedly 'second hand'.
I noticed the pedal felt spongy when just covering the brakes in moving traffic (30-40ish) then soon after I needed to come to acomplete stop to turn off, the pedal had some resistance but went completely to the floor, only applying a small amount of force. It would build up pressure if I pumped it but only briefly. I can't see any leaks and the fluid level's good but the master cylinder looks decidedly 'second hand'.
Nope, the pedal's still going to floor, very little resistance. The fluid, if anything, looks over filled (I'm sure I ckecked it when I serviced it a few months ago) and looks frothy (I'm in my suit so I can't get the cap off until this evening).
Is it possible to overheat brake fluid, and if so, what happens?
Is it possible to overheat brake fluid, and if so, what happens?
Yep - It's very possible to overheat brake fluid!
This is just a working theory but here goes. You said you were "pressing on" earlier the thread. You may well have overheated your brake pads & discs at this point which became screamingly hot.
You then immediately entered some traffic and had to sit for periods with your brakes on. The heat from your pads & discs then went straight into your brake fluid which boiled.
The boiling brake fluid intrduced air into the brake system (hence being frothy) and air means that the brake pedal will simply compress the air in the brake system and go to the floor rather than forcing the non-compressing fluid to act on the caliper. This is a common problem on track days.
So, you'll need to drain your brake fluid and replace.
Either that, or something else
This is just a working theory but here goes. You said you were "pressing on" earlier the thread. You may well have overheated your brake pads & discs at this point which became screamingly hot.
You then immediately entered some traffic and had to sit for periods with your brakes on. The heat from your pads & discs then went straight into your brake fluid which boiled.
The boiling brake fluid intrduced air into the brake system (hence being frothy) and air means that the brake pedal will simply compress the air in the brake system and go to the floor rather than forcing the non-compressing fluid to act on the caliper. This is a common problem on track days.
So, you'll need to drain your brake fluid and replace.
Either that, or something else
i would say that genarally 1.9 gti brakes are pretty crap as is.smiffy's explanation although i have heard of it on other cars i havent seen it on pugs before,
probably the master cylinder,that is quite common.
i would probably bleed the brakes and change all of the fluid if smiffy is right then it would be advisable.and will do your car more good than harm and that way you will find out wether the master cylinder has gone.
you tend to get brake fade after about 20 mins of hadcore driving in 1.9's
if you want to improve the braking you should upgrade them to gti-6 as they go straight on(calipers,discs,pads)(i think).
the rears are normaly good for braking but the arms which activate the handbrake sometimes fooks up i wouldnt worry about changing them unless they have gone wrong
probably the master cylinder,that is quite common.
i would probably bleed the brakes and change all of the fluid if smiffy is right then it would be advisable.and will do your car more good than harm and that way you will find out wether the master cylinder has gone.
you tend to get brake fade after about 20 mins of hadcore driving in 1.9's
if you want to improve the braking you should upgrade them to gti-6 as they go straight on(calipers,discs,pads)(i think).
the rears are normaly good for braking but the arms which activate the handbrake sometimes fooks up i wouldnt worry about changing them unless they have gone wrong
Yep - master cylinder it was, thanks for all your help!!
btw - the garage says 'oh, that'll be 100quid to fit a second hand one'
I said 'erm, yeah cheers but I'll source a new one if it's all the same with you, how much for just the fitting?'
oh, he says, just 50 then.
50quid for a SECOND HAND master cylinder!! my money was on it being my old one back after a quick scrub up with a wire brush and a new seal.
I really should find the time to do these things myself.
Anyway, safe again (hopefully!), thanks again, now where do I find a set of GTi 6 brakes
btw - the garage says 'oh, that'll be 100quid to fit a second hand one'
I said 'erm, yeah cheers but I'll source a new one if it's all the same with you, how much for just the fitting?'
oh, he says, just 50 then.
50quid for a SECOND HAND master cylinder!! my money was on it being my old one back after a quick scrub up with a wire brush and a new seal.
I really should find the time to do these things myself.
Anyway, safe again (hopefully!), thanks again, now where do I find a set of GTi 6 brakes
When they change the master cylinder make sure they change the fluid in the whole system. It's impossible to say what the fault was without seeing the car but I'm with Smiffy, seems like the fluid overheated.
All brake fluid (except DOT 5 which is silicon based) is extremly hydroscopic, which means it asbsorbs water. Rule of thumb is that after one year your brake fluid will be 1% water, 2 years 2% etc. Once the fluid reaches 3% water it's boiling point is reduced from approx 250 deg C to 110 deg C (curve goes nearly flat after that as it approaches water's boiling point).
The above is the reason you should always change brake fluid every three years. Sorry for sounding like an OAP, I can't talk, I haven't had mine done for four years, but then I live in Essex and the traffic is so bad I rarly see more then 50MPH anyway!
All brake fluid (except DOT 5 which is silicon based) is extremly hydroscopic, which means it asbsorbs water. Rule of thumb is that after one year your brake fluid will be 1% water, 2 years 2% etc. Once the fluid reaches 3% water it's boiling point is reduced from approx 250 deg C to 110 deg C (curve goes nearly flat after that as it approaches water's boiling point).
The above is the reason you should always change brake fluid every three years. Sorry for sounding like an OAP, I can't talk, I haven't had mine done for four years, but then I live in Essex and the traffic is so bad I rarly see more then 50MPH anyway!
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