Brake problem when engine running

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kitkat237

Member
Posts
56
Location
Hertford
Hello, have another odd problem, ok i wanted to change the brake fluid and front callipers so i so i use a brake bleeder to suck out the fluid rebuilt callipers went on well filled the fluid up and started bleeding back left, back right ,front left , front right with some one pumping the brake for me but what was happening was after it was pumped up it was fine till it was left up for 30 sec then it wound go down to the floor and took 3 pumps to get it back so i changed the Master cylinder bleed again and again and again now the problem is i have a grate peddle when the engine is off dues not fade stays at the top fine as soon as the engine is running the peddle goes way down about 4”-5” then starts to break and stops just shy of the floor the there disco dues stop like that but i have no idea what the problem is i have done an emergency stop and the abs cut in but there is something wrong when the engine is runny i think it has to be something with the abs the brakes was working fine before i started this so im shore that the master cylinder is fine as is the assister as are the callipers. i have bled my breaks like hmm 8 times now and put nearly 3 litters throw them so blending is not working, has anyone had any problems like this
 
Hello, have another odd problem. Ok I wanted to change the brake fluid and front callipers so i used a brake bleeder to suck out the fluid rebuilt the callipers, went on well, filled the fluid up and started bleeding back left, back right ,front left , front right with some one pumping the brake for me. But what was happening was after it was pumped up it was fine till it was left up for 30 sec then it wound go down to the floor and took 3 pumps to get it back so i changed the Master cylinder bleed again and again and again now the problem is I have a grate pedal when the engine is off, does not fade, stays at the top fine.

However as soon as the engine is running the pedal goes way down about 4”-5” then starts to brake and stops just shy of the floor. The disco does stop like that but I have no idea what the problem is, I have done an emergency stop and the abs cut in but there is something wrong.

When the engine is running I think it has to be something with the abs the brakes were working fine before I started this so I'm sure that the master cylinder is fine as is the assister as are the callipers.

I have bled my brakes like hmm 8 times now and put nearly 3 litres throw them so bleeding is not working, has anyone had any problems like this


After turning your incoherent rambling into something resembling English I think?:rolleyes: I understand what you are saying.

It is perfectly normal that the pedal will sink a bit when the engine is running as the vacuum servo is operating as it should.


Incidently it is usual to provide at least a minimum of information about the vehicle in question !!!! Such as model/year/engine type etc. Your profile only shows a Series II/III 2.25 diesel
 
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Hi sorry its been one of them weekend where nothing seems to go right

its a 1998 Land Rover Discovery V8i EFI 3.9

and sorry for rambling

and yes its meat to go down but it seems to go down well beyond what it did before ??
 
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you dont need engine running ,but either you still have air or master cylinder seals are going ,does it splash back in reservoir when pedal pumped
 
you dont need engine running ,but either you still have air or master cylinder seals are going ,does it splash back in reservoir when pedal pumped

yea it dues if u push it fast. I have bleed it lots so what am i missing im shore that its something to do with the ABS?
 
and if it was the master cylinder i would not get a good peddle when the engine is off or it would fade ? but the peddle is fine but as soon as the engine goes on im almost on the floor before it stops
 
you get a good pedal as servo isnt assisting so a little air etc is masked ,pedal can only go to the floor if there is air or excessive travel .with calipers a few pushes of pedal should remove most of travel and push pads against discs ,
 
you get a good pedal as servo isnt assisting so a little air etc is masked ,pedal can only go to the floor if there is air or excessive travel .with calipers a few pushes of pedal should remove most of travel and push pads against discs ,

the peddle dues work but very very low and i have pumped it and it doesn't change anything
 
Normally with the engine off, if you was to give the pedal a couple of presses it would be rock hard at the top and then only move when the vaccum comes into play(engine running) it's either air(which is compressable and would give very little braking potentional) or fluid is leaking from one of the calipers(poss not tightened enough) or its bypassing the master cylinder back into the res.
 
Why do you think it's something to do with the ABS?


Agree on that, the ABS only comes into play when it detects locked wheels when brakes applied. Driven by electrical signals and only input to the pedal is when it starts to thud letting you know it's worked.

But generally you know when it's working as by then you've filled your pants
 
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