Brake bleeding issues

fin170703 · Post by **fin170703** » Thu Aug 04, 16 9:01 am

Morning All...

Having changed the rear cylinders and shoes on my '73 roadrunner, I'm scratching my head a tad in regards to bleeding the system through

Has anyone got the correct procedure please ? I can't honestly say I've ever done it, so am probably going about it all wrong !!!!

I have the cover off the master cylinder and have cracked the rear bleed nipple. when I put my foot down on the pedal, something shoots brake fluid out of the master cylinder and all over the place ! with the cover on, I'm getting no fluid through what so ever, and I've tried both sides !!

someone help a pleb out please

Dave999 · Post by **Dave999** » Thu Aug 04, 16 9:11 am

get a mittyvac

pull the bleed stud out of the cylinder

wrap thread in Teflon tape

put it in and then back it out a smidge

open master cylinder

top it off

connect up mitty vac

remember that the lid has 2 connectors
the 1 that goes to the bottom of the reservoir goes to the bleed nipple

start pulling brake fluid through until its clean and any bubbles are not coming from the flow out of the nipple

lock it off

top up master cylinder

do the other side

try brakes

top off master and repeat until peddle is hard again

you may need to just connect the pipe to the nipple and not use one of the rubber couplers

mitty vac instructions are not the best

pip to plastic cup
pipe from inside lid to bottom of cup
pipe from other lid connector to gun

clean it out when done

Dave

fin170703 · Post by **fin170703** » Thu Aug 04, 16 9:17 am

I'll have a search for a mittyvac,

Can it be done without, or is it just a much easier process with one ?

Thanks loads for you help Dave, appreciate it

Charger · Post by **Charger** » Thu Aug 04, 16 9:27 am

I use a hand vacuum pump and 'suck' the fluid thro, found this method much more successful than pumping the pedal or 'eezibleed' devices

Something like this

http://www.ebay.co.uk/itm/Hand-Vacuum-P ... 2055801582

Dave999 · Post by **Dave999** » Thu Aug 04, 16 9:40 am

fin170703 wrote:I'll have a search for a mittyvac,

Can it be done without, or is it just a much easier process with one ?

Thanks loads for you help Dave, appreciate it

great for 1 person work

if there are 2 of you and one of you has bleed brakes before

its a case of push the peddle and lock off the bleed nipple when the fluid runs clear with no bubbles on the down stroke of the peddle

or cracking joints further back with the nipple at the cylinder closed to purge air out in between

but for 1 man job mitty vac works ok

Dave

fin170703 · Post by **fin170703** » Thu Aug 04, 16 9:51 am

Thanks Gents

fin170703 · Post by **fin170703** » Thu Aug 04, 16 10:00 am

I've got someone helping now, whos bled brake before

The fronts bleed no problem and when I build up the pressure in the pedal, and crack off the caliper bleed nipple, the pedal goes down to the floor (as youd expect) The problem is that I have a solid pedal even when I crack off the bleed nipples for the rear cylinders !

confused.com

Pete · Post by **Pete** » Thu Aug 04, 16 10:48 am

I have had a rear hose collapse internally such that I could take the rear drums off and still not get the slaves to move - that one does your head in!!!

fin170703 · Post by **fin170703** » Thu Aug 04, 16 11:03 am

I'm pulling my hair out pete

Fronts bleed perfectly but I cant get anything through the rears, I just get a squirt of fluid into the air ,from the master cylinder, and the brake pedal goes hard as a rock !!

I don't get it at all, they bled fine last week before I changed the rear shoes / cylinders

Dave999 · Post by **Dave999** » Thu Aug 04, 16 11:24 am

yes that is because the rears have been shut off totally by the danger burst pipe in the brake system switch.
its in the master cylinder or Distribution block up front

you have a safety/ danger switch in the system

if pressure is unequal between front and back the low side gets switched off

its a piston based thing that sits under the place where the brake failure light wire goes either into master cylinder or into the distribution block

you reset it by undoing the collar on the wire connector bit and allowing the break failure light switch thing move out until you hear a TOCK then you do it up again.

when it is blocking off one or the other circuit there should be a light on the dash. but many have had the bulb blow

this DANGER switch was used on cars from the very late sixties onwards.

Take a picture of your master cylinder and distribution block and we can all have a crack at pointing you to the thing. they all look a bit different
but if a wire connects to a spade or bullet its the other end of that thing that locks the piston and is keeping your rears off

I ran around for 6 months with the rears off and didn't know when I first got the car. my glowing bulb had been taped up behind the cluster to Aid with sale of the car to me

NICE.

Dave

fin170703 · Post by **fin170703** » Thu Aug 04, 16 11:30 am

That makes sense Dave,

The actual sensors wires are not connected but I guess this is a pressure based system that gets activated by un equal pressure ?

I'll give that a go now

Dave999 · Post by **Dave999** » Thu Aug 04, 16 11:36 am

Got it in one

undo that's switch's collar and pull it out 1/4 to 1/3 of an inch.

wire either never connected

taken off the last time the brakes were bled

or disconnected years ago to get the dash light off, I'm not casting aspersions I don't know who owned it previously, its more likely error than devious practice

keep in mind that you may need a full rear circuit master cylinder full to fill the pipes to the back

top off again before bleeding

and yes it will fountain up from the master a bit especially if there is lots of air pushing back

Dave

fin170703 · Post by **fin170703** » Thu Aug 04, 16 11:38 am

I'm thinking its the top connector, roughly in the middle ?

fin170703 · Post by **fin170703** » Thu Aug 04, 16 11:40 am

pulled it completely out and its a plastic connector !? not sure if I have the right bit

My mates dicking around with it as I type

Dave999 · Post by **Dave999** » Thu Aug 04, 16 11:42 am

anything without a pipe
but looks like it might have had a wire to it

basically the metal piston when locked in the Block off a circuit position
also earths the wire from the dash light and makes it come on

so a lump for a connector and a switch is 99% of the time the one you want

the piston is dumbbell shaped when it shuttles to one end the fat bit at that end blocks off the circuit and the fat bit at the other end gets locked by the end of the switch so it stays in poistion

Dave