Iffy brakes! is it the servo???

[leeparkes]

Right,all of a sudden my brakes have an issue.
with the car stationary put my foot on the pedal and it feels fine then after a few seconds the pedal starts sinking,
my first thought was to bleed them (so thats been done)
could it be the servo?

Thanks (in advance)

[daimlerman]

Strangely,I have a failed servo on my project!! The pedal is normal hieght,the brakes go on,but you need the strength of a superhero to stop... in your instance I would have a look at the flexi pipes whilst your helper holds the pedal down,reads like you are losing pressure somewhere to me.

[leeparkes]

Strangely,I have a failed servo on my project!! The pedal is normal hieght,the brakes go on,but you need the strength of a superhero to stop... in your instance I would have a look at the flexi pipes whilst your helper holds the pedal down,reads like you are losing pressure somewhere to me.

the brakes work as normal with no extra effort to stop it,
another example is,if im holding the car on a hill with the foot brake it will hold then after about 5 seconds it will start to release on its own,

do you mean the flexi pipes going from the servo to the inlet manifold?

[daimlerman]

Sounds like your servo is fine,I was refering to the flexi brake pipes,linking the solid pipe to the front calipers and the rear between the car frame and the rear beam.These fail in use by the internal wall of the flexi splitting allowing the pipe to swell up and the brake pedal sinks lower as more fluid is pushed into the pipe.MoT failure,BTW!

[maxfield]

Engine off, pump the brake pedal till it's hard.

Keep your foot on the brake pedal. Switch engine on.

If the pedal moves towards the floor the servo is working.

[daimlerman]

Engine off, pump the brake pedal till it's hard.

Keep your foot on the brake pedal. Switch engine on.

If the pedal moves towards the floor the servo is working.

You are paying attention at college,then!!How is the course going?

[maxfield]

Too easy at the minute...

Although we are moving onto transmissions

[E30BeemerLad]

Sounds like your master cylinder to me, pedal works initially, then as the seals let the fluid past the piston the pressure goes

[leeparkes]

Sounds like your master cylinder to me, pedal works initially, then as the seals let the fluid past the piston the pressure goes

would i be losing fluid though?

[E30BeemerLad]

don't think so, all the fluid that leaks past the seals will do is go back towards the reservoir i believe

[daimlerman]

don't think so, all the fluid that leaks past the seals will do is go back towards the reservoir i believe

Would have expected the fluid to escape to the servo body?

[E30BeemerLad]

good point malcolm

Note to Zoners, do NOT take heed of any mechanical advice from me

[zimmer-320i]

well it depends if its a double piston servo, tho do the test looking at the joints and flexi pipes if they show no leaking or bulging then its your servo, job jobbed

[town325i]

if your servo was shagged it will feel like your trying to move a house with your feet. pedal creaping under pressure is the fluid moving somewhere it shouldnt and more than likely leaking some where what car is it and does it have rear drum brakes if it does have a look at the wheel cylinders that are hidden in the drum. if there are discs on the rear check the flexi brake hoses and joints

[leeparkes]

if your servo was shagged it will feel like your trying to move a house with your feet. pedal creaping under pressure is the fluid moving somewhere it shouldnt and more than likely leaking some where what car is it and does it have rear drum brakes if it does have a look at the wheel cylinders that are hidden in the drum. if there are discs on the rear check the flexi brake hoses and joints

its an 88 325i (rear discs)

[leeparkes]

Im back!
ive checked ALL the hoses an lines with the wife on the brake pedal and everything is good
no leaks,no bulges,no issues.
im not losing any fluid either!

ive timed the brake pedal travel,from pressing hard it takes about 7 seconds before my foot is on the floor,there is good pressure to begin with and is not spongy!

so is it the servo?

[zimmer-320i]

i think you may find its the master cylinder, not the servo its self. there not overly priced and a good place to start, if you have no leaks nor bulding etc then its the master cylinder for sure

and town... my servo went on a corrola gti 1989, and it held pressure then slowly creeped to the floor and to stop i had to pump the pedel


infact also try the vacum hose first!

then its the master next mate im afraid!!

and ive seen 3 masters go in my driving history so i know what to expect with them and it does sound like it if all other cecks come up none

[leeparkes]

and town... my servo went on a corrola gti 1989, and it held pressure then slowly creeped to the floor and to stop i had to pump the pedal

this is similar to whats happening!

[zimmer-320i]

defently master then mate
maybe get a seal kit if your handy at dimantling and putting back together, but i just found it eaiser to replace the whole lot its brake pipes off, two/three bolts to master take that off and new one on, bolts done up pipes done up, bleed the brakes job jobbed

[leeparkes]

Im doing an M50 on it in a couple of months so it has to be changed anyway for a smaller diameter one.
ive never had problems with brakes so dont really know much about them.
thanks

[zimmer-320i]

this is from gsf
B65025 BRAKE MASTER CYLINDER E30 325i 87>92 66.90

i pursume yours is non abs?

bmw is proberly 300 quid lol

[zimmer-320i]

then id replace it with the smaller one now
then your ready for it later on.

what one fits, the golf mk 2

[leeparkes]

then id replace it with the smaller one now
then your ready for it later on.

what one fits, the golf mk 2

im going to find out,i think clio one fits too.

[zimmer-320i]

go for a golf one, how can u even bring yourself to put french tat on german engernieering!!

[E30BeemerLad]

better pedal feel has been noticed with the clio servo

[leeparkes]

better pedal feel has been noticed with the clio servo

ive put a post in the engine swap section

[zimmer-320i]

master cylinder! servo is the big black part behind it!!!!!!!!!!!!!!!!!!!

[E30BeemerLad]

sorry, everyone is at cross purposes here...

The fault with the brakes does indeed seem to be master cylinder, which needs replacing.

With the M50 swap on the horizon, the smaller servo will be needed and out of the golf and clio varieties, the clio one seems to provide a better pedal feel according to some who have done a few swaps.

I've retained the E30 master cylinder with the clio servo in my M50 swap

[leeparkes]

master cylinder! servo is the big black part behind it!!!!!!!!!!!!!!!!!!!

when the servo is swaped for a clio/golf etc one
im sure a different master cylinder is used (audi i think)

[shedrool83]

Sorry to hijack your thread but my brakes are crap and after reading this i think its the servo.
I really have to stand on the pedal to get anything like brakes.
I have fitted new pads and have near new drilled/grooved disc front and back.
I've also replaced the fluid and bleed the brakes.

But if i do maxfields test the pedal does go down when i start the engine.

[cracker]

If the master cylinder fails,dont you lose fluid?

[MrAsp]

I have this problem (master cylinder KO) on my '84 320i.
Where can I find on the net a replace kit for my M/S?

I've surfed the web, but I didn't find anything.

My car has got an "ATE" master cylinder, without ABS.