Bleeding front brakes...

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JimK
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Bleeding front brakes...

Post by JimK »

I replaced the front cylinders last weekend, and I can't seem to get the pedal solid again. It's taking a couple of pumps of the pedal to get them properly firm.

Any tips on getting all the air out? I've started bleeding at the furthest brake from the master and worked towards the nearest.

I can see a couple of places that might trap air:
in the forward cylinder where thefluid comes in from the top and exits at the bottom, there might be a pocket of air at the top of the cylinder. How do I force the air down and through to the other cylinder and hence out of the bled screw?
The other place is the brake switch, and I think I can just unscrew it slightly until all the air is out.

Next to be changed will be the rear cylinders, so any tips for that will be gratefully recieved :-)
Jim - New Forest, the Wiltshire bit
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paulhumphries
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Post by paulhumphries »

I assume you bled the rears as well ?

Paul Humphries
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JimK
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Post by JimK »

paulhumphries wrote:I assume you bled the rears as well ?
Yes - when I say that I started with the furthest brake from the master I meant I started with the nearside rear and worked towards the offside front.
Jim - New Forest, the Wiltshire bit
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flying
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Post by flying »

i had this problem with one of the rears when i did my sisters car and eventually found out that the bleed nipple was completely blocked so replaced it with a new one and it sorted it....do you have a servo?....if you do then you could use the bleed kit that puts it under pressure and it should push it out...also are the brakes adjustment right so they can move and be able to pump the fluid out
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JimK
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Post by JimK »

flying wrote:i had this problem with one of the rears when i did my sisters car and eventually found out that the bleed nipple was completely blocked so replaced it with a new one and it sorted it....
Both are fine, I cleaned them out when I removed them from the old cylinders.
do you have a servo?....if you do then you could use the bleed kit that puts it under pressure and it should push it out...
Don't know what you mean by that. I have a simple non-return valve bleed tube from Gunson that works very well - I can see that no air is getting back in. Unless it gets back in through the bleed-screw thread.
also are the brakes adjustment right so they can move and be able to pump the fluid out
Yup, one more click on the adjuster and the drums lock.
Jim - New Forest, the Wiltshire bit
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paulk
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Post by paulk »

Peetee and I have one of the Gunson Ezi bleed kits but haven't yet successfully made it work on the standard cylinder.

Maude took about 3 attempts at bleeding to get a solid pedal. And even then as I'd changed the front shoes it felt abit soft for a while till the shoes bedded in.

The brake switch wouldn't work on Maude till i got all the air out of it. I ended up filling it with fluid and very quickly spin it over and onto the housing.
Paulk


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JimK
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Post by JimK »

I heard the Ezi-bleed is difficult to use with the Minor cylinder so I bought the simpler bleed tube thingy.
I'll have another go or two at bleeding them over the weekend, and try the brake switch thing. It currently works, but there might still be air in it.
Jim - New Forest, the Wiltshire bit
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paulk
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Post by paulk »

The little tube with a split in is all I've actually used ,successfully, so far but does take some perseverance. :(
Paulk


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Packedup
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Post by Packedup »

Are you definitely seeing air when you re-bleed?

If not then are the cylinders all properly adjusted?

Do you know for a fact the master is OK (as posted frequently on here, bleeding with an old master can cause damage to the seals due to the wear ridge that develops over the years)?

I've spent days in the past trying to get rid of air in a system, only to find it's not air at all, buit a failing master...
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JimK
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Post by JimK »

I saw some bubbles the two times I bled it, and I guess there's more but I was wondering if there was a trick for getting it all out.

A couple of stabs on the pedal build good pressure and the pedal doesn't gradually sink at all, so I figured the master is OK. I'm not losing fluid, either.
Jim - New Forest, the Wiltshire bit
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alex_holden
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Post by alex_holden »

I successfully used my Eezibleed on Fenchurch, but I had to modify the master cylinder filler cap to fit it because the kit doesn't come with a suitable cap.
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Alex Holden - http://www.alexholden.net/
If it doesn't work, you're not hitting it with a big enough hammer.
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Packedup
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Post by Packedup »

JimK wrote:I saw some bubbles the two times I bled it, and I guess there's more but I was wondering if there was a trick for getting it all out.
I go for the pump the pedal up qickly, really jabbing it, then press it hard whilst getting someone else to crack open the bleed nipple.

ut if you're not able to bleed till there's no air, then you either have a hell of a lot of air, or air is somehow getting in. Possibly of course through the bleed nipple threads if it's been loosened a little too far. Unless you have an infinite air generating device in your lines ;)
A couple of stabs on the pedal build good pressure and the pedal doesn't gradually sink at all, so I figured the master is OK. I'm not losing fluid, either.
A good stab will cause the seal to expand and be pressed against the cylinder wall far quicker than a gentle press though. So it's not a definite it's all good. Certainly I'd not discount it if you still get no joy after bleeding the system a couple more times...
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RogerRust
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Post by RogerRust »

I was taught to use a 1 2 3 method

1 a sharp push about half the way down

2 repeat above

3 A long push all the way down then tighten the nipple before coming off the pedal.

obviously this requires an assistant!

The short sharp taps lossen the bubbles then the long push moves them down the tube.
My wife was helping me to do this, but I hadn't fixed the steering wheel on. When she pushed the pedal she pulled back on the steering wheel and smacked herself in the face with it! She got her own back by treading on me as she got out of the car while I was lying down bleeding the brakes! :evil:
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bmcecosse
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Post by bmcecosse »

I use simple piece of plastic tube plus jam jar with some fluid. Make mug of coffee, connect tube, other end in jar, open bleed nipple - drink coffee - while keeping an eye on the master cylinder level. It self bleeds. Never failed me yet!
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minor_hickup
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Post by minor_hickup »

Ive been meaning to try this method, especially as its so hard to find good help, especially when they find blipping the horn hilarious.
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bmcecosse
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Post by bmcecosse »

Pull the wires off the horn!
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flying
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Post by flying »

minor_hickup wrote:Ive been meaning to try this method, especially as its so hard to find good help, especially when they find blipping the horn hilarious.
or working on a police car and some one decides to switch the sirens on :evil:
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ColinP
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Post by ColinP »

I bought a spare M/c cap them modified it by drilling and tapping a hole for the standard thread in the Ezi-bleed kit.

Bleeding the brakes was easy as a 1 person operation, after I replaced both cylinders (sheared the bleed nipple off!).

It has the advantages that you dont have to use the full travel of the master cylinder (and run the seals on the corroded part of the bore!), it's easy to see how much fluid is left in the reservoir (so you don't pump more air into the system!)
And, by golly, you can use a lot of fluid!

Cheers,

Colin
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