v8bobber Posted August 29, 2009 Share Posted August 29, 2009 Hi all, I have been trying to bleed the brakes on my trialler this evening, but without any success whatsoever. The servo / master cylinder arrangement has been taken over from a disco 1, along with a load of the other bits. When I pushed the pedal a small amount of fluid seemed to go from the reservoir and then when the pedal was released the fluid came back in again! So, just assuming that there was an air lock in the system as all the brake lines were new I disconnected them at the master cylinder to see how much fluid was coming out i found the answer - not much. I had a bit of a pathetic spray from each of the four junctions but that was about it. The brakes were working a treat when the donor vehicle was driven into the garage last year so was a bit surprised this time around when they didn't work. It has been a little while though. I took the master cylinder apart and the seals appear to be ok although the pistons seem a quite scored. The inside of the cylinder itself is perfect. I'm not familiar with the inside workings of a brake master cylinder and hope that someone with more knowledge might be able to advise me if there is something else that might be messing with the workings of it before i go and spend £££ on a new cylinder. Bearing in mind that this will only be used off road Hope someone can assist. TIA Dave Quote Link to comment Share on other sites More sharing options...
steve_d Posted August 30, 2009 Share Posted August 30, 2009 Have you used the whole disco brake arrangement i.e. cylinder, servo, pedal box? If not you may have a mismatch between the parts one of the common ones being that the pushrod is the wrong length and not allowing the master to either travel far enough or not return far enough. Steve Quote Link to comment Share on other sites More sharing options...
Les Henson Posted August 30, 2009 Share Posted August 30, 2009 Sometimes the master has to bled seperately from the rest of the system - especially if it was completely empty. Disconnect one pipe, press the pedal, place your finger over the hole and release the pedal. Do this once or twice for each pipe outlet/until you get a good jet of fluid out of each outlet. The system can be bled as normal once the master is done. Les. Quote Link to comment Share on other sites More sharing options...
v8bobber Posted August 30, 2009 Author Share Posted August 30, 2009 Cheers both, I know that the parts are matched because I have used as many parts from the donor vehicle as possible. The only part that isn't V8 disco are the rear calipers and unfortunately the fluid hasn't made it that far. Les, I think u are probably right. It just doesn't make sense that the master cylinder doesn't work all of a sudden. I've taken it apart already so I might try and fill the master cylinder first after blocking the oulet holes up and then put it back on and try and bleed it from there. I am reluctant to buy a new master cylinder when it was working perfectly before! Didn't help that I snapped the yellow cover off it mind so might have to get a new one anyway!! Ill let you know how I get on Dave Quote Link to comment Share on other sites More sharing options...
steve_d Posted August 30, 2009 Share Posted August 30, 2009 I don't know this master cylinder so I may be all wrong here. On the RRC there is a brake fail warning switch that screws into the side of the master cylinder. This must be undone a few turns before you can bleed the system. There are also two systems going to the front calipers and these must also be bled in a specific sequence. If the disco setup is the same I can look up and post the bleed procedure for you. Steve Quote Link to comment Share on other sites More sharing options...
SteveRK Posted August 30, 2009 Share Posted August 30, 2009 I suggest checking that the very, very small air bleed hole in the master cylinder (assuming it has one) is not blocked. ~The purpose of the hole I think is to allow air to be displaced from within the master cylinder seal chamber. This hole is normally in alignment with the cylinder to the main fluid hole. Quote Link to comment Share on other sites More sharing options...
lrfarmer Posted August 30, 2009 Share Posted August 30, 2009 Sometimes the master has to bled seperately from the rest of the system - especially if it was completely empty. Disconnect one pipe, press the pedal, place your finger over the hole and release the pedal. Do this once or twice for each pipe outlet/until you get a good jet of fluid out of each outlet. The system can be bled as normal once the master is done. Les. this is the same problem i'm having at the moment my master started playing up. but now i can't get any fluid out of the brand new one. i was starting to think the servo had packed up not the master cylinder Quote Link to comment Share on other sites More sharing options...
v8bobber Posted August 30, 2009 Author Share Posted August 30, 2009 Mr Henson, Go to the top of the class, or maybe we both can. I managed to glue the little plastic pipe and reassembled. I blocked the outlet pipes with bleed screws from the rear calipers and 'backfilled' the master cylinder that way. Then, did Les' little trick and now seems to be squirting out a treat! You would not believe how close I came to buying a new master cylinder, Les I can now afford to buy you a pint or two. I have considered though that the fluid squirting out may just be the fluid a backfilled the cylinder with, I am confident however. Once I've had my cup of tea I will try the rest of the system. Everything is crossed! Regards, Dave Quote Link to comment Share on other sites More sharing options...
v8bobber Posted August 30, 2009 Author Share Posted August 30, 2009 Update, I have just spent a fruitless hour trying to get some fluid down the pipes and have failed! I think I might have to invest in one of those pressure bleeder things that you connect the spare tyre to! Quote Link to comment Share on other sites More sharing options...
bishbosh Posted August 31, 2009 Share Posted August 31, 2009 You mean you haven't got an Ezebleed????? Get one ASAP they are bluddy fantastic. Quote Link to comment Share on other sites More sharing options...
v8bobber Posted August 31, 2009 Author Share Posted August 31, 2009 You mean you haven't got an Ezebleed????? Get one ASAP they are bluddy fantastic. Have never used one but it's the only way I can see to get the system to bleed. I think it must just be the fact that there is absolutely no fluid in the lines. I looked on the Halfords website last night and they've got one in stock. Have got the two kids today so they are going to be coming with me whether they like it or not! I have never had problems with brakes before like this. Even when I renewed all the brake lines on the P38, they bled straight away without any hassle. Fingers crossed for today, after all, what are Bank Holidays for! Dave Quote Link to comment Share on other sites More sharing options...
steve_d Posted August 31, 2009 Share Posted August 31, 2009 Ezeebleed is the way to go. When you use the spare tyre make sure it is down to about 15psi. If you have it too high it compresses the bubbles in the pipes and being smaller they are reluctant to move along. I expect you would just be happy to have bubbles in the pipes at this point in time. Steve Quote Link to comment Share on other sites More sharing options...
landmannnn Posted August 31, 2009 Share Posted August 31, 2009 I am using one of these kits Using an airline it sucks fluid through the bleed nipple and the fancy bottles keep the reservoir topped up. Filling and bleeding a dry system takes about 15 minutes instead of two days! Quote Link to comment Share on other sites More sharing options...
v8bobber Posted August 31, 2009 Author Share Posted August 31, 2009 Well, finally got the brakes working today, after much cursing. I am less annoyed though than I would have been if I had invested in a brand new master cylinder only to find out that it wasn't that at all. I am quietly chuffed that the brake lines that I have lovingly made up by hand are leak free (at the moment). The only problem I have, which i'm not too bothered about at the moment is that the rear nearside caliper is a bit sticky and the pistons only have a few mm of movement, but seeing as the pads are new that shouldn't be a problem. I forgot to mention previously that things were made more tricky as I also have front calipers on the back at the moment as once the trialler is up and running then i'll be able to put some fiddle brakes on it. Happy just to have a set of operational brakes at the moment though. The Haynes manual (which I bought for the wiring diagram - another nightmare) showed the front calipers with only one bleed nipple, the one at the top, so thats the one I used to bleed it. It was only when I looked in an old Range Rover manual that I realised that one is for the primary circuit and the other is for the secondary circuit. Most of you will probably know (but i'll put it on here incase it helps anyone else in the future!) but the top bleed screw and the innermost one have to be bled at the same time, and the the remaining one bled after that. I quickly did that on both sides and the brake pedal was absolutely solid. I might give the p38 brakes a going over when it comes in the garage next week to change the airbags. I wish I had read the post about lowering the pressure in the tyres before using it. Initially I used the wrong cap, as one is very similar, and that coupled with about 40psi meant that the garage roof and my recently prepped bonnet had a liberal coating. I also had a bit of a brake fluid shampoo which did not amuse me. I wrongly assumed that one of the old tyres on the trialler would do the job as I used to run them at 14psi. I must have pumped them up at some point and not realised! Lesson learnt. Once it was set up properly though it was a joy to behold. Unfortunately I do most of the stuff in the garage fairly late at night so knocking someone up to do me a favour and press the pedal was out of the question. When I eventually get a day off I will try and take it up and down the lane and see how many complaints I get! It sounds like one of those Icelandic hill racer things at the moment. It's proably about time that I added a picture aswell. It looks pretty much identical in the picture as it does now, except for a fine mist of brake fluid over it!! Everyones help is much appreciated Dave Quote Link to comment Share on other sites More sharing options...
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