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Madcal

Member
Afternoon all,

My Range has developed a braking issue. The brake light (not ABS) sometimes stays on after starting, you have no assistance on the brakes and stopping when in drive requires almost full body weight on the pedal (so terrifying in traffic). After 5 minutes or so the light goes off, assistance returns and all is well. Brake fluid is to the top and no leaks.

I took it to my specialist and of course it worked perfectly on 3 test drives…

Now it is home again, first drive I did the light stayed on and I had no assisted brakes.

I cannot really drive it now, obviously until I sort this out.

I plan to do the ABS test procedure (with the shorted connector, ABS relay out and count the flashes), I have ordered a new ABS relay anyhow as someone on a US forum seemed to fix theirs with a new relay.

If anyone has any other ideas of things to check I would really appreciate it. A “new” brake servo/ABS unit is v v expensive and it may not even be that anyhow.

Many thanks in advance.
 
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I don't know your car model, but if it uses the WABCO braking system like the P38 and has an electric pump for the brakes with an accumulator sphere, then it is likely that the accumulator has failed so is not holding pressure. It therefore takes time for the pump to build up pressure.
 
I think Datatek is right. I had this a good few years ago now. New accumulator sorted it. If you've never done a full bleed on the brakes proceed with caution. You absolutely must follow the workshop manual, there are no shortcuts and if there is a lot of air in the booster, accumulator and pump you may need a lot of brake fluid to get it fully bled.

Forgot to say, pump should run for not more than 45 seconds, if it does there is a problem. Also, if the pump runs after just two full brake applications the system needs bleeding.

One other thing before getting too far in, check your front wheel bearings. If there is play the caliper pistons can be pushed back slightly meaning you get a soft pedal that can be confused with a booster problem.
 
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classic kev said:
I think Datatek is right. I had this a good few years ago now. New accumulator sorted it. If you've never done a full bleed on the brakes proceed with caution. You absolutely must follow the workshop manual, there are no shortcuts and if there is a lot of air in the valve block, accumulator and pump you may need a lot of brake fluid to get it fully bled.
Click to expand...
+1 ^^^^^^ and if the fluid has not been changed for a long time, a full fluid change should be done.
 
That is all very kind and super fast responses thank you.

Fluid was changed a year ago (500 miles) and done By a specialist not me.

Brakes are perfect really solid pedal except when light on and then a lower down but still solid pedal except takes a body weight to stop the car instead of a light push.

Would all make sense as a weird accumulator failure as you all describe since it is intermittent and with me disappears after a few minutes driving.

Given the warnings over complexity and my lack of time I think I will get just the local Landy specialist to fit a new accumulator and go from there.

thanks again!
 
classic kev said:
I think Datatek is right. I had this a good few years ago now. New accumulator sorted it. If you've never done a full bleed on the brakes proceed with caution. You absolutely must follow the workshop manual, there are no shortcuts and if there is a lot of air in the valve block, accumulator and pump you may need a lot of brake fluid to get it fully bled.
Click to expand...
+1 ^^^^^^ and if the fluid has not been changed for a long time, a full fluid change should be done.
Madcal said:
That is all very kind and super fast responses thank you.

Fluid was changed a year ago (500 miles) and done By a specialist not me.

Brakes are perfect really solid pedal except when light on and then a lower down but still solid pedal except takes a body weight to stop the car instead of a light push.

Would all make sense as a weird accumulator failure as you all describe since it is intermittent and with me disappears after a few minutes driving.

Given the warnings over complexity and my lack of time I think I will get just the local Landy specialist to fit a new accumulator and go from there.

thanks again!
Click to expand...
Fitting the accumulator is a piece of cake. 30 presses on the brake pedal to get rid of any residual pressure, unscrew the old accumulator, screw new one on. No bleeding needed.
 
Datatek said:
+1 ^^^^^^ and if the fluid has not been changed for a long time, a full fluid change should be done.

Fitting the accumulator is a piece of cake. 30 presses on the brake pedal to get rid of any residual pressure, unscrew the old accumulator, screw new one on. No bleeding needed.
Click to expand...

I will go for it then. However it is an asymmetrical risk, the brakes sort of work at the moment. So I can drive it to the garage (slowly). If I do this and make a mess of it then it will be 100% un-driveable and I will need to get it trailered. I am handy with a spanner and have 2 Series 2a’s in nut-and-bolt resto at the moment, but I am v shy of more modern stuff. Time to get my big-boy pants on!
 
Madcal said:
I will go for it then. However it is an asymmetrical risk, the brakes sort of work at the moment. So I can drive it to the garage (slowly). If I do this and make a mess of it then it will be 100% un-driveable and I will need to get it trailered. I am handy with a spanner and have 2 Series 2a’s in nut-and-bolt resto at the moment, but I am v shy of more modern stuff. Time to get my big-boy pants on!
Click to expand...
You cannot really go wrong as long as you depressurise.
 
Any tips for how to access it, given it is down low under a bunch of stuff on the classic rather than mounted on top like a P38?
 
It will be a couple of weekends before I can do it. Will post photos and experience in here for others to use in the future.

Thanks again for all the responses, accumulator ordered plus ABS relay. Hopefully I don’t also need a pump.
 
Madcal said:
It will be a couple of weekends before I can do it. Will post photos and experience in here for others to use in the future.

Thanks again for all the responses, accumulator ordered plus ABS relay. Hopefully I don’t also need a pump.
Click to expand...
As brake pressure comes up eventually, the pump would seem to be working.
 
Check power connections to pump also, could be loose connector/ corrosion causing pump to only work intermittently.
 
Afternoon all,

Firstly a massive THANK YOU for all the advice.
The new accumulator arrived, £160.
I have the workshop manual so followed the steps; battery off, press brake 30 times, wait 60 seconds then 4 more to get rid of the pressure.

Then I tentatively started undoing the connections to the accumulator.

I had rags ready and was expecting brake fluid fountains… nothing, only a minor drip.

On a 1990 you have to remove the wheel arch lining to get to the bolts on the back of the accumulator, which took the most time.

Then old one off, new one on, tighten up the connections (I do hate brake line connectors, it is 400 x 1/8 turns with a spanner).

Put battery back on, turned ignition on, pump went on for 30 seconds, brake light went out and we have a solid brake pedal.

Started her, stuck in gear and rolled forward, brakes solid and work.

1 hour.

Have to check for leaks tomorrow but all seems great and so far no need to bleed them.

Thanks so much for all the help.
 
Madcal said:
Afternoon all,

Firstly a massive THANK YOU for all the advice.
The new accumulator arrived, £160.
I have the workshop manual so followed the steps; battery off, press brake 30 times, wait 60 seconds then 4 more to get rid of the pressure.

Then I tentatively started undoing the connections to the accumulator.

I had rags ready and was expecting brake fluid fountains… nothing, only a minor drip.

On a 1990 you have to remove the wheel arch lining to get to the bolts on the back of the accumulator, which took the most time.

Then old one off, new one on, tighten up the connections (I do hate brake line connectors, it is 400 x 1/8 turns with a spanner).

Put battery back on, turned ignition on, pump went on for 30 seconds, brake light went out and we have a solid brake pedal.

Started her, stuck in gear and rolled forward, brakes solid and work.

1 hour.

Have to check for leaks tomorrow but all seems great and so far no need to bleed them.

Thanks so much for all the help.
Click to expand...
Nice one:D
 
Datatek said:
Nice one:D
Click to expand...
So we are 5 months on and the light is back on again, same symptoms (no assistance, full body weight required even to stop creep in drive).

Turn the car off and on again and the light goes off and it all works fine.

I am thinking it must be electrical given it is intermittent. Going to do the blink test from the manual but if anyone has any other ideas I am all ears.
 
Madcal said:
So we are 5 months on and the light is back on again, same symptoms (no assistance, full body weight required even to stop creep in drive).

Turn the car off and on again and the light goes off and it all works fine.

I am thinking it must be electrical given it is intermittent. Going to do the blink test from the manual but if anyone has any other ideas I am all ears.
Click to expand...
Does the pump run? If not, check the connector to the pressure switch on the pump. On the P38 there have been occasional failures of the pressure switch reported.
 
thank you, the pump is humming away when I tested today but then the light went out today..

I will check that when the light remains on; would be good if it wasn't as I am sure an easier fix.
 
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