P38A Calipers front

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Baileyroverq

Baileyroverq

Active Member
Posts
167
Location
Woodley Berks
Hi all, I have a bit of a problem: you see I checked the front brakes on wife's 2.5 dse and found the piston dust covers were shredded so I bought new calipers and fitted them fine. The problem is the bleed of them. I had clamped the hose off before, so I assume just gravity bleed, then a couple of pumps of the pedal would do it- but no! Soft pedal after 3 go rounds so do I really need to bleed the whole system for changing the front brakes only? Many thanks in advance.
 
Baileyroverq said:
Hi all, I have a bit of a problem: you see I checked the front brakes on wife's 2.5 dse and found the piston dust covers were shredded so I bought new calipers and fitted them fine. The problem is the bleed of them. I had clamped the hose off before, so I assume just gravity bleed, then a couple of pumps of the pedal would do it- but no! Soft pedal after 3 go rounds so do I really need to bleed the whole system for changing the front brakes only? Many thanks in advance.
Click to expand...

No front brakes are hydrostatic and are bled normally WITHOUT any pressure in accumulator.
 
Thanks for the help so far am having another go tomorrow any ideas how to get to the rear master bleed nipple as it is tucked up under the fire wall and difficult to see let alone loosen and tighten when needed
 
Baileyroverq said:
Thanks for the help so far am having another go tomorrow any ideas how to get to the rear master bleed nipple as it is tucked up under the fire wall and difficult to see let alone loosen and tighten when needed
Click to expand...

If you clamped the front pipes there should be no need to bleed the entire system. Bleed the R/H front first then the O/S front. Front brakes are bled without pressure in the accumulator (depressurised ignition OFF), rear brakes are bled with pressure in accumulator. Ignition on for four seconds then off and bleed. Repeat as required and are done AFTER fronts have been bled. .
 
So couldn't get the fronts to bleed and went for the full bleed i.e. master, fronts, front master, rear master, rears engine on 4 off 4 still nothing but can I assume if the accumulator is kicking in every time the pedal is pressed and it is taking over 55 seconds to fill initially that it needs replacing and that is why I still have no pressure to the pedal.
 
Baileyroverq said:
So couldn't get the fronts to bleed and went for the full bleed i.e. master, fronts, front master, rear master, rears engine on 4 off 4 still nothing but can I assume if the accumulator is kicking in every time the pedal is pressed and it is taking over 55 seconds to fill initially that it needs replacing and that is why I still have no pressure to the pedal.
Click to expand...

The fronts are bled WITHOUT any pressure in the accumulator with the ignition off. If the accumulator is taking 55 seconds to fill you have a problem should take no more than 40 after being stood for a while. (Over night). The rear brakes are bled AFTER the fronts which are hydostatic, by turning the ignition on for 4 seconds then switching off, then bleeding repeating as needed. Rear brakes will not bleed without pressure in accumulator.
 
I do hope it's not the pump Brian it isn't making any strange noises just the accumulator coming on and off
And wammers I did the bleed exactly as you state in your reply but still had soft pedal, if using a power bleeder if I buy one do you still do the 4 second on/off for the rear brakes thanks again
 
wammers said:
The fronts are bled WITHOUT any pressure in the accumulator with the ignition off. If the accumulator is taking 55 seconds to fill you have a problem should take no more than 40 after being stood for a while. (Over night). The rear brakes are bled AFTER the fronts which are hydostatic, by turning the ignition on for 4 seconds then switching off, then bleeding repeating as needed. Rear brakes will not bleed without pressure in accumulator.
Click to expand...

I think if there is air in the system it will struggle to pressurise and keep pumping. Make sure the power circuit has no bubbles at all coming out. Shine a bright torch on the bleed tube.
 
Grrrrrr said:
I think if there is air in the system it will struggle to pressurise and keep pumping. Make sure the power circuit has no bubbles at all coming out. Shine a bright torch on the bleed tube.
Click to expand...

Before he clamped the front flexis and changed the calipers he should have depressurised the system. Instructions in RAVE are quite explicit. All he would then have needed to do is bleed the front calipers. If you do a complete bleed all is done WITHOUT ignition on (NO pressure in accumulator) until step 13. If he has not followed the instructions then he will have to do a full bleed. The TC lamp should go out within 40 seconds to indicate usable pressure. But the pump may continue for some seconds after that to achieve full pressure. He needs to read RAVE instructions and follow them.
 
See service repair 70.55.92 Land Rover workshop manual which is the same as RAVE which is what I work from no mention of depressurisation of abs before caliper removal the only thing I think I may have done too soon was press the pedal to seat pads before the bleed but then when I decided to do the full bleed it was done by the book so to speak exactly by the book
 
I got air in the reservoir once. Took forever to bleed it all out of the power circuit.

The accumulator is simple and relatively cheap (not as cheap as brake fluid though!) But the pump is way more. Odd it worked before though.
 
Baileyroverq said:
See service repair 70.55.92 Land Rover workshop manual which is the same as RAVE which is what I work from no mention of depressurisation of abs before caliper removal the only thing I think I may have done too soon was press the pedal to seat pads before the bleed but then when I decided to do the full bleed it was done by the book so to speak exactly by the book
Click to expand...

See, ABS > REPAIR
ABS general service information.

DEPRESSURISE SYSTEM
WARNING: Before bleeding the system or
working on any component in the brake
system the following procedure MUST be
carried out to depressurise the accumulator.
1. Switch off ignition.
2. Operate the brake pedal 30 times. Pedal travel
will increase slightly and reduced resistance will
be felt as pressure decreases.
3. Wait for 60 seconds, press the brake pedal four
more times. This procedure will ensure that all
pressure is evacuated from the system.

There you go, listen and learn ignore and fail. ;);)
 
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