broke brakes

First as a green newbie would like to say how happy i am to have found this forum, as have a lot to learn.

I am an australian living in Tanzania where I just bought a Range Rover classic (2-door V8 petrol, 5-speed manual) in Arusha that is a town near the northern border of Tanzania and drove it 1100km to Mtwara that is a town near the southern border of Tanzania. Quite a trip!

Everything started off fine but about half way (shortly after Dar es Salaam) the brakes decided to stop working. The village mechanic had never seen a Range Rover before but managed to deduce the problem was the brake server, so I got a bus back to Dar where I could not find an original replacement but instead found a used Range Rover EFi86/87 brake server & master cylinder that the chap who sold it to me was ready to swear on a crate of gin would work just as good as the original. The village mechanic bored some new holes in the RR body to mount the replacement server & cylinder then did his best to bleed the brakes with the result that the brake system was working just enough for me to limp the remaining 350km to Mtwara.

Now I am trying to figure out if the Range Rover EFi86/87 brake server & master cylinder really is compatible with the Range Rover Classic and if it is then why the brakes are not working as they should?

When I press the brake pedal the brakes work but only just and not nearly as well as they should. However I am not losing any brake fluid and the server and cylinder seem to build up pressure correctly (but maybe not enough). So maybe the problem is the brakes have not been bled properly?

Any advice about the best way to troubleshoot what could be the problem would be most welcome.

There's a couple of us in UK exploring this syndrome too mate ...
http://www.landyzone.co.uk/lz/f10/brake-failure-but-i-dont-understand-why-194754.html

I'm currently working through fitting new springs and shocks all round, and giving the calipers a good once over while in there. I have fitted a new master cylinder and completely renewed the fluid, but the problem still returns.

The big mystery is that after an 80% brake failing, continueing on for a few miles (slowly), the brakes come back to full operation again.

Let us know if you find a cause/soloution.

Johnny.

How about flexi hoses breaking down internally whereby fluid flow is restricted? Normally that would show up by not freeing off properly and bleeding them doesn't always flush out the bits because they are too big to squeeze through the journals.

Thanks for replying Johhny. Good to know that I am not the only one with this problem. Actually I figure the most likely cause is dementia (mine not the RRC) but also suspect a problem somewhere in my RRC's brake system.

I also found that the problem was not consistent. After the village mechanic had tried to bleed the brakes for a day his mate got fed up and revved the engine with the result that the performance of the brakes got better before slumping back into the doldrums again later in the day???

When I put my foot down on the brake pedal there is a sound of air wooshing somewhere in that area and I have to press very hard before I get any response. But the pedal always springs back to the normal position. Does this sound to you more likely to be the server & cylinder or the bleeding of the brakes?

I'm an RRC learner on here too Windhorse, but with your symptoms, I would strongly suspect a duff servo is involved, but not the only culprit.

BH ... good point, worth checking further. I'm flushing all the pipes with a vaccuum pump pulling new fluid through as I go. Pulling fresh fluid through the flexi-pipes while they are disconnected, should flush any crap through, but I've only done one corner as yet.

Next attack will be all day Saterday when extra hands are available.

Johnny.

jwm said:

I'm an RRC learner on here too Windhorse, but with your symptoms, I would strongly suspect a duff servo is involved, but not the only culprit.

BH ... good point, worth checking further. I'm flushing all the pipes with a vaccuum pump pulling new fluid through as I go. Pulling fresh fluid through the flexi-pipes while they are disconnected, should flush any crap through, but I've only done one corner as yet.

Next attack will be all day Saterday when extra hands are available.

Johnny.

Click to expand...

Change all flexi pipes to braided, I know that there is a cost but trust me it is worth doing. You might also want to check the rear bias valve (also called pressure reducing valve). HTH.

windhorse said:

When I put my foot down on the brake pedal there is a sound of air wooshing somewhere in that area and I have to press very hard before I get any response. But the pedal always springs back to the normal position. Does this sound to you more likely to be the server & cylinder or the bleeding of the brakes?

Click to expand...

If you can hear air wooshing you have an air/vacuum leak. Check vac hoses for splits/tears and general perishing. If a vac hose is split then you won't have full servo assistance meaning a loss of brake power.

Got a local mechanic to take a look at the brake system. Pressure ok at all four outlets of the master cylinder but no pressure whatsoever at the back wheels. Hmmm... This mystery was partly solved when we disconnected the rear pipe on the top of the brake pressure reducing valve that is just under the cylinder and found somebody had inserted a tiny ball bearing into the pipe!!! Turns out this is a trick used by local mechanics who don't know how to fix a part of the brake system that is not working properly - they just plug whatever part is not working with a ball bearing or nail head to maintain pressure in the system and leave you driving around with three or less working brakes rather than the full set after you pay them for fixing your vehicle.

:violent:
Lots to learn.

After removing the ball bearing from the pipe all brakes were bled and the whole system worked very well.... for about half an hour, after which the brakes slowly got softer and softer again. Does this gradual loss of pressure indicate a leak in one of the pipes??

I will return to the workshop on Monday to continue the troubleshooting. From what I have read in the owners workshop manual it looks as if the problem is in the primary brake circuit rather than the secondary one, as despite the loss of braking power the brakes continue to work a little though not nearly as well as they should. Fortunately the workshop has a drive-on brake testing system that will enable us to identify which wheel is not braking properly as a starting point for further investigation.

Sounds like you've reverted to the problem the last owner had which is good. At least you have a clear plan of where to go from here now and fix it properly. If the rear end has been blocked off or restricted then it would indicate the problem is there. When it works is there breaking effort at all four wheels? i.e. are all discs shiny or is there one at the back with more rust than the other (although where you are I won't suspect there is much rain)? Bear in mind a diagonal split brake system so a problem at one rear wheel could also point to a problem at the opposite front (I'm having a braking prob at the moment too but not like yours). When your brakes are 'soft' jack it up and check each one by spinning the wheel and applying the brake. If there is no discernible pull to left or right when driving and all 4 are working albeit weaker than the should be then still suspect servo hose or seals.

Got the opportunity this morning to test the faulty brakes of my RRC on a drive-on multi-tester system that showed the brakes on all 4 wheels are working evenly but only at about half the braking power they should be delivering (120 on the multi-tester scale). This is consistent with my road tests over the weekend that indicate the brakes though very soft do work a little but not nearly as good as they should.
Trying to figure out what this means we have concluded so far that if brakes on all 4 wheels are delivering even braking capacity then the problem in the system is more likely to be a central one rather than air or a leak in any of the pipes that deliver brake fluid to each of the wheels.
Hmmm... next step is to disassemble the master cyclinder that is now the primary suspect in this on going investigation to see if the rubbers are ok or if it needs to be rebuilt or replaced, right?

try this first bleed brakes looking from inside front/right f/l r/r r/left.

front/right f/l r/r r/left.

thanks for this suggestion pete@her! why do you suggest to start bleeding the brakes at the front right (closest to the brake cylinder) rather than at the back furthest from the cylinder?