Bleeding brakes..any ideas?

Post by **minor_hickup** » Sat May 06, 2006 4:35 pm

OK so i seem to have upset my brakes while changing the lower trunion. So i've tryed bleeding them to no avail...still a spongy pedal. So i thought maybe i damaged the flexible hose at some point, so I changed that. Tryed re bleeding several times, still a spongy soft pedal that goes to the floor. I realised that the L-shaped piece at the rear on the offside was dripping a little fluid, so i tightened it up and its fine, no drips; must have moved it when using the bleed nipple. So i went round again several times and still nothing!

I did search this site for ideas. I've used the method where you pump the pedal up, apply pressure, open the nipple until the pedal goes to the floor, then close and repeat. I dont seem to be getting any air out but still no hard pedal! BTW I have been topping up the master cylinder as I go round. I can't find any leaks at all apart from the chassis leg where the master cylinder is located; however I did spill a fair bit of brake fluid when aiming for the filler. All wheel cylinders are just over a year old and I've checked they're not leaking.

I'm hoping I've missed something glaringly obvious and someone will point it out to me, so any ideas?

Post by **chickenjohn** » Sat May 06, 2006 4:41 pm

Its possible your master cylinder is on the way out!

One started to go soft on me like that, then suddenly failed- no brakes at all!

Post by **minor_hickup** » Sat May 06, 2006 4:43 pm

It has been suggested by a few people i've asked for help from. However like the wheel cylinders is just over a year old and the last thing I want to do is replace the m/c and find out its not at fault! Im just praying its not the m/c!

Post by **chickenjohn** » Sat May 06, 2006 4:47 pm

do you have a servo on the braking system?

Post by **chrisd87** » Sat May 06, 2006 4:50 pm

Did you disconnect or disturb any of the solid pipes when doing your trunnion? I had a similar problem when I replaced one of my wheel cylinders and it turned out that one of the ends to the pipe connecting the front cylinders had split and was allowing air in, but no fluid out.

Post by **bmcecosse** » Sat May 06, 2006 5:05 pm

maybe the brakes are just not adjusted up close enough to the drum. Does the pedal 'pump up' if you press it repeatedly?

Post by **minor_hickup** » Sat May 06, 2006 5:11 pm

No servo, have meticulously checked where solid pipes connect. I adjusted the front brakes after doing the trunion. The back were done the weekend before and have tried bleeding with them adjusted and slacked right off. The pedal will pump up, but then loses any pressure so the pedal will go right to the floor again.

Post by **bmcecosse** » Sat May 06, 2006 5:21 pm

If none of the cylinders or pipes are leaking - it would indeed point to the master cylinder. Does NO air come out any of the nipples when bleeding ?

Post by **minor_hickup** » Sat May 06, 2006 7:44 pm

yeah i got some out at first. But nothing the last few times i've been round other than the air in the tube. Any chance I've dislodged some crud thats ruined the seals in the m/c?

Post by **rayofleamington** » Sat May 06, 2006 7:47 pm

do you get a little air bubble rising in the m/c after presing the pedal? If so then m/c is shot.
(carefull not to shoot brake fluid in your eye whilst investigating - if working correctly they make a little 'fountain' in the reservoir when you press the pedal)

Post by **minor_hickup** » Sat May 06, 2006 7:50 pm

i havent used the brake pedal with the cap off, but will try that tomorrow. Im too sick of the smell of brake fluid to do it now.