Brake Bleeding Problems

[thunderstarter]

Hi all, can anyone advise on this? Ive had all 4 calipers off the car, changed a rigid pipe from the abs box and fitted all flexi hoses.

I filled and bled the system at each caliper with a 'gunson easy bleed' kit using the following orderrear o/s, front n/s, rear n/s, front o/s)

i then disonnected the beed kit, pumped the brake pedal and then refitted bleed kit and repeated the bleed prceedure above again.... clean air free fluid came out at all 4 corners. However, when I started the car and moved up and down the drive to test it, the pedal kept going from firm to soft (to the floor).

What have I done wrong?

ive read somewhere on here, if doing brakes, you also need to bleed th clutch at the same time?!? if this is true, how is it done? And would this possibly cause my problem?

ta
Dan

 

[ian hosk]

Hi Dan

I can't see that you would need to do the clutch - they should be totally separate (ive been a qualified mechanic since the 80's and never needed to do this).

Its best to do the wheel furthest away from the master cylinder 1st, then the next etc and finish with the closest last. Ive never used an easy bleed kit, just a person in the car to pump the pedal and a person with a bit of tube and a container(to catch the old fluid) and a spanner for the bleed nipple on each corner.

I have had, very rarely, found that on older cars the fact the brake pedal is going to the floor this is travel the master cylinder plunger would normally not do so the unused part of the cylinder chamber can damage the master cylinder seals - but this is very unlikely.

If you are getting a 'spongy' pedal there is air still in the system - you won't need to start the engine to bleed the brakes as the brake fluid part of the system runs separate to the vacuum servo assistance part(the vacuum comes from the engine when its running)

Any more probs let me know and I'll try to help

Ian

 

[k1ano]

Clutch and brakes are fed from the same reservoir with the clutch system feed quite high up so the clutch can be impacted if the brake fluid is low but not generally the other way round ...

Sometimes due to abs and rear limiting valves bleeding requires slow pedal depressions also ...

Martin

 

[jimm]

HI did have a service a couple of years ago and i asked for them to replace the brake fluid. There response was that they would do it but be awear that some times they get a problem with the master cylinder when draining the fluid. ???? All was good when they done it but they had to make me realise the cost issue if it failed. Hope yours is an easy fix buddy .
jimm

 

[ed_harland]

Read section 38c in the workshop manual in the knowledge base

 

[hualpa_jo]

Are you aware of there beeing two bleed nipples each side? In my early days I once thought I could bleed only the outer one of a 4piston caliper which made me run into a lot of trouble since it has been relied on me...

To bleed a brake system is a service task and Renault is very generous to give it's fluid 4 years. Other manufacturers give it only 2 years so running into problems seems like lack of knowledge/wrong methods to me, unless the nipples are completely oxidised but I'm not even sure the vee has alloy calipers on the rear.

Also as long as you haven't replaced a special hydraulic part (abs/valve) there is nothing to pay special attention to.

 

[thunderstarter]

Thanks for all the replies guys, in the end i was faced with a situation of getting the car trailered to a garage to have ths sorted ( too dangerous to drive as there was literally no pedal) or buy a professional vacuum pump. So i spent £70 on a vacuum pump today from machine mart.

Link >

It works off an aircompressor at about 80psi and to be honest i'd bled each caliper maybe 8 times with an easybleed kit without success, with the vacuum pump I had the job done in an hour.

I now have solid pedal..... what a carry on its been to get this job done!

 

[RUSSO]

We now know where to come Dan, thinking of doing mine sometime soon
Good result pal :salut:

 

[thunderstarter]

We now know where to come Dan, thinking of doing mine sometime soon
Good result pal :salut:

Phil, if you ever need to borrow the kit, you are very welcome. (it was a complete pig of a job that I hope I dont have to repeat again in the near future!

My new seats and steering wheel are ace by the way!