Many thanks for your thoughts. If the master cylinder is at fault why does it seem to behave without the servo? Is there a rebuild kit suitable for the abs master cylinder?
Many thanks for your thoughts. If the master cylinder is at fault why does it seem to behave without the servo? Is there a rebuild kit suitable for the abs master cylinder?
jamesmartin
Well-Known Member
you apply less pressure on the cylinder push rod and so seals, a new cylinder is better
sierrafery
Well-Known Member
maybe if the longest pipes were not bled at all but as long as all the pipes are well bled no air should be trapped in there no matter in which order you bleed them... that LR sequence has other more complicated explanation which has to do more with safety but it's too long for me to write it in english... as about the OP's problem i have serious doubts it's about air in the system, my first suspect is the servo unit
Many thanks, would your suspected fault be amenable to repair with the rebuild kit or replacement?
Cash is tight and i am keen to try and avoid replacing too many expensive components.
jamesmartin
Well-Known Member
im not sure of your thinking ,how can a servo make a pedal sink underfoot ,that has to be air ,passing seal or ballooning flexi
sierrafery
Well-Known Member
I dont know anything about a servo unit repair kit... when it comes about brakes aka safety i'm always biting the bullet and fit new genuine parts though the master cylinder being suspect too better start with that cos it's cheap and even if you'll have to get a servo too never regret that you have a renewed braking system
My thoughts also, but having had no bubbles of any significant nature in 3l of brake fluid flushed through since i got the thing a balooning flexi would quite potentially fit the bill.
jamesmartin
Well-Known Member
get someone to pump the pedal and see if you have fluid splashing in the resevoir
sierrafery
Well-Known Member
my thinking is based on the following description cos there is a possibility to be an internal leak and when vacuum is applied the pushrod to travel forward without pressure to the brakes to be fully released... possibility which is in that fault chart as well IMO a master cylinder seal leak should be noticeable without servo assistance too...though i sustain my purple signature
Shall do. Am i right in thinking your logic is that a feirce splash from a contracting flexi should produce a visible retun of fluid to the reservoir?
jamesmartin
Well-Known Member
brake fluid cant be compressed it would have to have air or a leaking seal for the pedal to sink whatever pressure the servo applied, you cant push the pedal without the push rod moving into the master cylinder
jamesmartin
Well-Known Member
not quite splashing shows poor master cylinder seals
Do i do this test with engine running or can it be done with engine off.
She is a noisy beast and i dont want to disturb the neighbors (they put up with a lot and always offer a hand).
jamesmartin
Well-Known Member
engine off
Back in a minute...
jamesmartin
Well-Known Member
i think id start with the master cylinder, another thing you can do is clamp each flexi one at a time and see if clamping each has the same effect
jamesmartin
Well-Known Member
you cant avoid it just bleed at each inlet and outlet by slackening the fittings pressing pedal and hold till fittings retightened the let pedal up repeat till clear fluid appears then repeat the same at the calipers
So chaps, new master cylinder fitted and it is much better. Interestingly it was a non abs master cylinder fitted.
Still some air in the thing by the feel of it but i will try and hunt it down on monday. With a swift pump i can now get the abs to activate going downhill so hopefully that will push the air into the more easily bleedable parts.
Some other issues arose on the trip, see new thread if you could kindly guide me.
Still some air in the thing by the feel of it but i will try and hunt it down on monday. With a swift pump i can now get the abs to activate going downhill so hopefully that will push the air into the more easily bleedable parts.
Some other issues arose on the trip, see new thread if you could kindly guide me.
