Just want a bit of a vent and maybe some ideas?
Long story but I will try to keep it short –
System is a twin MC and balance bar setup.
So I swapped the engine in my J15, bumped a brake line causing a minor leak, on the OS rear solid to flexible connection. Cut old flare off copper
line, made a new flare and that looks good, no leaks.
Wanted to change my front MC to a larger size, did this no problem no leaks.
Time to bleed the system, fronts go ok, MC has minimal travel when pedal pushed – great.
Rears, I cannot get to bleed and the MC pushes all the way in practicaly. No apparent leaks, so I swap my old front MC for my rear MC fearing a
flipped seal. No difference. Pedal just pushes the rear MC all the way in practically.
I have tried 2 man bleeding – a Gunson 1 man bleeder and both methods together.
I also remade the flare on the pipe going to my rear MC as it looked a bit squashed and rough. This made a tiny difference.
I made short length of pipe and connected directly to the MC to see if there was air still in there, but it bled just fine. It seems air only is
present at the rear bleed nipples.
I guess now I must re visit the rear flexi/copper I originally “fixed” but there are no traces of fluid leaks, but I understand one way leaks are
possible, air in but no fluid out, is this likely?
When I first built the car and made the brake system, it went so smoothly – no leaks, bled easily and brakes were fine, so to not be able to work out
where the problem is, is really bugging me.
Any ideas on how to tackle this? This is really bugging me and I am getting through a LOT a fluid!
Like I said, sorry for the venting and rambling story.
I would start by cracking off the connection at the master cylinder, bleed there then move backwards cracking off each connection in turn and bleeding until you find either the system bleeds or you find a restriction . It would probably pay to take the bleed nipples out and check they are clear. Best of luck
^^ what he said, its really the only way to find the problem...
[Edited on 26/5/2014 by mcerd1]
Cheers guys - never occured to me to try to bleed through the fittings. I will give it a go.
thanks
I had similar symptoms when I first put the kit together, very similar setup to yourself. I had a persistent but small leak in one of the rear flexi hoses. I eventually replaced both hoses but for some reason it was very difficult to get the air out of the rears. Only achieved success by repeatedly alternating sides where bleeding was taking place could I get a hard pedal (maybe about 10 times). I cannot offer logical explanation. Hope this helps.
What rear calipers are you using? If they're Sierra then you'll need to take them off and make sure the bleed nipple is uppermost.
Out of interest what's the new engine?
quote:
Originally posted by RichN
What rear calipers are you using? If they're Sierra then you'll need to take them off and make sure the bleed nipple is uppermost.
Out of interest what's the new engine?
Beat me to it!! Have you remember to remove the bottom mounting bolt and spin the calliper so that the bleed nipple is uppermost to avoid that irritating little air pocket??
quote:
Originally posted by Paul AS
Beat me to it!! Have you remember to remove the bottom mounting bolt and spin the calliper so that the bleed nipple is uppermost to avoid that irritating little air pocket??
There are lots of source of problems with these, but after I struggled for a while I found that bench bleeding the master cylinder made the critical
difference for me. It was a Wilwood one.
http://www.wilwood.com/m/techtip/TechFaqAnswer.aspx?id=10&no=1
edited to say
I put this down to the fact that when bleeding the rears the back of the car is jacked up and so the air can't get out of the master cylinder so
easily because it is nose down. This may not be the explanation but it works for me.
[Edited on 27/5/14 by matt_gsxr]
I would start with the rear calipers. If you haven't turned them so that the bleed nipple is uppermost then that will be the simplest place to
start.
Keep us posted.
Just another thought....and probably obvious to those who know about it (I didn't!) but...Some calipers don't work with the direct threaded
brakeline, they reqire a banjo type connector. I learnt this the hard way while trying to bleed my front hispec's. Basically, I could not get any
fluid to flow into the caliper...turns out that it wont flow with a direct threaded brake line. BUT, if you back off a little on the tightening, it is
is possible to get some fluid in the caliper, and thus lulling you into thinking all is well.
Could this be the case whith your set up?.
quote:
Originally posted by Jenko
Could this be the case whith your set up?.
quote:
Originally posted by mcerd1
quote:
Originally posted by Jenko
Could this be the case whith your set up?.
this shouldn't be an issue with his sierra calipers though
it may be something as simple as kink in one of the copper lines or a bit of muck blocking one of the connections, bleeding it one joint at a time from the master cylinder will eliminate a lot of possible causes....
quote:
Originally posted by monkeyarms
also tip the caliper so the nipple is as uppermost as possible
) 
And the prize of an internet cookie goes to RichN and anyone else that said "nipple uppermost"
Lots of air came out once i rotated the caliper about and bled with nipple uppermost. Was almost too easy!
Cheers guys
Glad you got it sorted out - the human memory is a wonderful thing - when its working!!
This thread solved my hours of pain trying to get the rears working right - drop the bottom bolt from slider rotate the calliper round and bleed , make sure the piston don't get chance to pop out , thanks to all of the above for restoring my sanity :-)