Rear brakes not bleeding

[TR5tar]

OK, you'd have thought I'd have learnt my lesson when it comes to fiddling with things I know little about, but I haven't and now find myself with a brake problem. As some might remember from a recent thread of mine, I was going to change my brake fluid, because what I had in there was at least 3 years old and quite probably a few years older. My brakes did seem to be working well and the fluid didn't look very dirty, but I thought better safe than sorry, so yesterday I set about the task. Never having done this before, I thought I'd read up on it, watch videos, buy the gear ... all I've which I did so I felt confident.

 

Got the Easybleed kit, but couldn't get the proper cap (cheaply), so speaking with neighbor about it he said he had one of the vacuum type "bleeders" and said I could borrow it. So, watched the videos on it and seemed straightforward. Got to work, starting with bleed screw furthest from m/c. Fluid came out, but not in continuous flow, went to offside wheel, and the same happened. Yes, I'd removed old fluid from m/c first, but left some in their, and had then topped up with new.

 

So, tried fronts (which are discs, drums at back), and they bled exactly how I thought they should. Fluid come out in continuous flow and went down in m/c, which I kept topping up. Soon fluid ran clear. All good then at fronts I think.

 

OK, I thought, perhaps I'm not getting a good vacuum seal on the rears using this gadget, so I'll have a crack at the two person method. Pulled son away from video games, sat him in car, and told him to press brake as I loosened bleed screw and to lift when I tightened it. Again, some fluid came out in squirts, but not continuous flow and eventually it stopped coming altogether ... I'm now just getting air and brake pedal is spongy. We've done it over and over, but nothing. And yes, there's still fluid in the m/c ... that's just sitting there.

 

Thankfully, one of our group members is going to pop over in the week and help, but I'd love to be able to fix it without putting anyone out. Have I made a simple error somewhere along the lines? Son said that when he pressed the brake pedal, that it went to the floor with the fronts, but only half way when I was working on the rears.

 

Sometimes I just wish I could get a job right the first time

[ianc]

I'm no expert on brakes after the TR4s, but you have split front/rear braking system, I believe, so I would be inclined to suspect either the brake booster or the flexibles to the rear drums.

The fact that both rear brakes are failing to bleed suggests it's more likely to be the booster.

Ian Cornish

Edited May 7, 2017 by ianc

[barkerwilliams]

Darren,

 

I have found that vacuum bleeders easily draw air from around the thread of the loosened bleed screw as there is less resistance than drawing the fluid through the system..

 

Air can have only entered the system via a nipple, unless the fluid level was too low in the reservoir. Sounds as if you have a technique issue.

 

Never "open" the nipple, ease it open ever-so-slightly and let the pressurised fluid force its way out.

Never open the nipple before assistant starts to press, and always shut flow off early.

 

With an assistant depressing the pedal, do not open the nipple until they have started to press on the pedal. Watch the fluid leaving the nipple perhaps three inches of fluid into the capture tube, on subsequent bleeds close the nipple off early when perhaps only two inches of fluid has flowed, repeat five or six times then top up the reservoir. The fluid is always then under positive pressure and air cannot enter via a nipple

 

 

Alan

[Guest ntc]

http://www.halfords.com/motoring/engine-oils-fluids/brake-clutch-fluid/europat-vizibleed-bleed-aid#reviewDetails

[Graham Harris]

If the pedal doesn't go all the way to the floor there must be a restriction some where try loosening the first flexible line at the rear, loosen the front joint first and try for a full pedal to the floor if that works go to the next joint until you find the problem

 

Graham

[TR5tar]

Thanks for suggestions so far ...

 

Hi Ian, I'm not sure what the booster is. If it's a problem with that, does it mean replacement, or is it something that can be repaired?

 

Hi Alan, There's a good chance it is my technique, but I've had another try doing as you suggest and only opening the screw slightly. I think I definitely was opening it too much before. However, still no fluid coming through.

 

Hi Neil, Thought I'd give your suggestion a go, so headed to local Halfords only to find that they don't have one in stock until Tuesday. Typical.

 

Hi Graham, I'd sort of like to think it's actually something I'm doing wrong, rather than an obstruction, as that sounds like a difficult thing to fix. It's above my pay grade, as they say ... certainly above my skill level!

 

Cheers, Darren

[Guest ntc]

Darren

All you need to do the same is a lenth of pipe and a jam jar

Pm me a phone number if needed

Edited May 7, 2017 by ntc

[Nigel A]

I've always used the Halfords tool that Neil recommended and it's always worked for me with no problems even when starting from a completely empty system

 

Cheers

 

Nigel

[Cew]

With the vacuum bleeder it is possible to suck fluid at a very high rate, I am wondering if it has emptied the section of the M/C (it has a smaller reservoir for the dual system built into it) to fast and is not getting replenished .

[TR5tar]

Thanks all. I've now tried the jam jar (well Coke bottle) method ... drilled hole in cap, put a length of clear pipe through into some old fluid at bottom, second small hole in top of cap. Unfortunately still getting lots of air. Then reverted to vacuum method and did start getting some fluid through, but just trickle (not filling pipe) and lots of bubbles in container. So, still sucking lots of air.

 

I've noticed that there are two compartments in the m/c, with a smaller one to the front, that I think serves rear brake, but that looks full. Does it fill from the larger compartment, or does it need filling separately?

 

I've chucked tools, pulled hair out, and cried ... now I'm closing the garage door and sitting in the sun. When I've recovered I'll have another crack and have a chat with you Neil.

 

Cheers, Darren

[Eddie Cairns]

Wrong idea so deleted nonsence I wrote.

Edited May 7, 2017 by Eddie Cairns

[rcreweread]

Darren

 

Get an assistant to pump the pedal to get as hard a pedal as you can, hold the pressure on the pedal and then undo the nipple. The high pressure in the system should be noticeable as soon as you open the nipple, either in the form an escaping hiss of air, or a noticeable squirt of fluid or both.

 

As soon as the pedal hits the floor, your assistant says down, and/or you see the speed of any fluid diminishing, close the nipple. Check master cylinder for topping up and repeat process until air has been expelled.

 

Sometimes you need the extra pressure to get enough air out, to start the master cylinder pumping fluid rather than air - often a simple down stroke of the pedal is not enough - this is effectively what the pressurised systems do, but this way you are in more control.

 

Cheers

Rich

[Cew]

The smaller reservoir is the second stage one if the main system should fail, and yes it fills from the rear one but, I think ,on an overflow basis as you fill the rear. It does need to be full. As in my previous post vacuum bleeding can drain this one quite quickly and I think that is where your problems stem from.

Richs' idea should get you going (stopping!) again.

Edited May 7, 2017 by Cew

[Guest ntc]

The smaller reservoir is the second stage one if the main system should fail, and yes it fills from the rear one but, I think ,on an overflow basis as you fill the rear. It does need to be full. As in my previous post vacuum bleeding can drain this one quite quickly and I think that is where your problems stem from.

Richs' idea should get you going (stopping!) again.

Wrong the small one is rear only.

[Cew]

Quite, but then I assumed that most second stage systems work the rear brakes.

[Guest ntc]

Tis why it is called a duel system

[Cew]

Still needs to be filled up.

[Guest ntc]

Still needs to be filled up.

In it's own right as no fluid will come from the other.

[Cew]

In it's own right as no fluid will come from the other.

 

How can that happen without a separate filler?

[Guest ntc]

Go downhill and brake like sh!!! it may spill over the bridge

[TR5tar]

Well, got back to it late yesterday evening after reading comments here and doing some head scratching and by 2am had made some progress.

 

It was in the end a school boy error on my part. I had not appreciated that I had to fill the chamber for the rear brakes (the small one at front of reservoir) separately, so it had run down too low. Once I'd worked that out the fluid came rattling through the rears. Both done now, although I think I'll go around again, just to make sure that there's no air.

 

Thanks everyone for the advice and offers of help. I'm never going to make a mechanic, but when I bought the car I promised myself that I'd learn to do at least the basic maintenance, servicing type jobs. Anyhow, will finish up and take it for test run this afternoon. If you don't here back from me, you'll know I got it wrong

[Guest ntc]

Well done next

[John Morrison]

Way you go darren,

 

be chuffed with yourself, this is how we all learn, and no one knows everything.

 

John.

[pinky]

 

loved the story Darren,

 

can't wait till you have to change the clutch

 

have you got the brown bible, of (how to do)

 

pink

[rog1]

Good work Darren!?

 

Are you still on the test run?

 

Atb