master cylinder -the geyser effect

Post by **Dru** » Sat Aug 22, 2009 6:30 pm

Another day, another prob sorted, anotherother prob feared...

I've just changed out one of the front brake cylinders, as it was seized solid. Started bleeding the new one through, and I found that, with the filler cap off the master cylinder, a spurt of brake fluid shot up out of the hole whenever I pumped the brake pedal.

Is this normal?

Post by **bmcecosse** » Sat Aug 22, 2009 6:44 pm

Absolutely normal - just put the cap on - and don't fill the m/c right to the top - leave 1/2" space.

Post by **Dru** » Sat Aug 22, 2009 6:49 pm

phew. It's been a bit one-damn-thing-after-another lately

Post by **bmcecosse** » Sat Aug 22, 2009 6:52 pm

Relax - have a cuppa! (Or a G & T!)

Post by **cormorant** » Sat Aug 22, 2009 8:28 pm

Glad to hear that's normal then as mine does that. I got in the habit of putting the plastic cap off the brake fluid over the hole while I was pumping the pedal. Didn't know the correct term for it was the geyser effect. Is the term for the brakes themselves the mild friction effect?

Post by **bmcecosse** » Sat Aug 22, 2009 8:36 pm

Unless they are Wolseley brakes !! In which case - "powerful friction effect"! My W brakes were slightly 'smelly' today on some long/steep descents aroung Glen Croe/Hell's Glen - but no loss of braking effect whatsoever!

linearaudio · Post by **linearaudio** » Sat Aug 22, 2009 9:30 pm

Post by **mike.perry** » Sat Aug 22, 2009 10:41 pm

My Wolseley brakes are OK but I wouldn't say the are spectacular. Maybe the linings aren't the best quality.

Post by **bmcecosse** » Sun Aug 23, 2009 4:42 am

Linings do seem to be a variable feast. I have one set which are TOO good, the older set on the car at present are great - and i have a st of 'TR7' linings in the background waiting to be tested.

Post by **Dru** » Sun Aug 23, 2009 10:33 am

Is the term for the brakes themselves the mild friction effect?

I think it could formerly have been described as the 1945 General Election effect; wild swings to the left...

Just had another bout of bleeding and a whizz down the street; managed to lock up the front brakes on braking. Much scrunching of gravel. This is good!

Post by **cormorant** » Sun Aug 23, 2009 10:45 am

Oh good yes they should lock up really if they are in good nick - mine do now too - had a terrible job bleeding them though, they are not the easiest brakes to bleed and different people seem to have different methods for doing it.

Post by **Dru** » Mon Aug 24, 2009 5:20 am

So I surmised, having read through some older threads. I'd been dreading the bleeding -it always seemed to take for ever on my motorbike - but I simply used one of those bleeding kits which consist of a little tube with a non-return valve in, and did it single-handed. I still live in hopes that my daughter will develop an interest in things mechanical, and don't want to put her off for life by getting her sitting there pumping the brake pedal while I drone "In.... out...." all afternoon

Post by **rayofleamington** » Mon Aug 24, 2009 11:13 am

I simply used one of those bleeding kits which consist of a little tube with a non-return valve in,

better than that is to cut the NRV off the end! Then sit the end of the tube in a jar of waste fluid. This way if there is any slight suck back, it will pull fluid back in to the system rather than pull air down the (loose) threads of the bleed screw.

if you use a plastic jar with a lid, and feed the tube through a hole in the lid, it reduces the probablility that the jar falls over and spills / smashes on the floor. If you make the hole an oval shape, it will grip the tube but still allow air out when you're bleeding.

Post by **tingo** » Thu Aug 27, 2009 6:54 pm

Great advice about using a jar lid with a hole in it.
I usually end up using both hands, both feet and my teeth to bleed brakes. I'll give it a go. Thank you!!

Post by **bmcecosse** » Thu Aug 27, 2009 7:32 pm

Oh dear - I just have a mug of tea! While Mr Newton's invention gets on with the job!

Post by **cormorant** » Thu Aug 27, 2009 8:21 pm

Never used it for this application though I have found it generally quite handy for holding things down

linearaudio · Post by **linearaudio** » Thu Aug 27, 2009 9:36 pm

cormorant wrote:Never used it for this application though I have found it generally quite handy for holding things down

Think how bad it was before Newton discovered it!!
Everything floating all over the place

Post by **tingo** » Thu Aug 27, 2009 9:39 pm

gravity is a myth - the earth sucks

Post by **Kevin** » Fri Aug 28, 2009 9:45 pm

tingo wrote:Great advice about using a jar lid with a hole in it.
I usually end up using both hands, both feet and my teeth to bleed brakes. I'll give it a go. Thank you!!

Great stuff sounds like you have turned into a work of art