tez162003 Posted September 3, 2012 Share Posted September 3, 2012 I am having a nightmare bleeding my brakes. I had the calipers sand blasted and powder coated, but cant seem to bleed them properly, also the bleed nipples don't want to seal properly so under high pressure it seeps out through the threads. I put this down to debris in the line stopping it from sealing, So it needs a thorough bleeding. Anyone an expert in these matters or has a pressure bleed kit? Quote Link to comment Share on other sites More sharing options...
Daryl Posted September 3, 2012 Share Posted September 3, 2012 Im in MK,but know nothing about bleeding brakes im afraid. Quote Link to comment Share on other sites More sharing options...
M13KYF Posted September 3, 2012 Share Posted September 3, 2012 always found the bleeding kit on the Zed not great. Best is a two man jjob Quote Link to comment Share on other sites More sharing options...
tez162003 Posted September 3, 2012 Author Share Posted September 3, 2012 I've actually tried bleeding it with 2 people. the pedal stayed insanely spongy, completely drained, re filled and bled yet still spongy as hell, and when you push the pedal hard fluid drips out the bleed nipples. (not good) But without bleeding it enough to drive I can't even get it done at a garage. Be okay if the bleed nipples would just seal. Cross threaded a caliper yesterday, luckily I had a spare. Quote Link to comment Share on other sites More sharing options...
BulletMagnet Posted September 3, 2012 Share Posted September 3, 2012 Do bleed nipples have O-rings? Quote Link to comment Share on other sites More sharing options...
glrnet Posted September 3, 2012 Share Posted September 3, 2012 Can't remember, might be worth PM'ing SMD he had some nipple issues recently and did quite a bit of research as I recall. Do bleed nipples have O-rings? Quote Link to comment Share on other sites More sharing options...
daveparkin Posted September 3, 2012 Share Posted September 3, 2012 Do bleed nipples have O-rings? Nope, they seal on the cone at the bottom of the nipple where it sits into a conical metal seat on the caliper - i.e. it is a metal-to-metal seal a bit like a compression joint in plumbing. You can get a thread sealant specifically for them (I think its made by speed-bleeder), but that is only to stop residual fluid that is up the bore of the nipple weeping-out of the threads over time. It is not the threads that stop the bleed nipple leaking. My Brembos mysteriously started leaking from the bleed nipple threads one day, and I took the car to my local Nissan HPC with whom I had a warranty. They told me it happened quite often on GTRs, which also have Brembos. They took my bleed nipples out, cleaned-up the ends and swapped them all around - been fine ever since, but I'm not looking forward to the possibility of the problem returning after the next fluid change! Maybe you should buy some new bleed nipples all round? With respect to not being able to 'get a pedal' by bleeding, did you clamp the lines (you have to be careful doing this, as it could damage some lines) to minimise air ingress while you changed the calipers? Did the reservoir run dry during bleeding? In either of these cases, I would imagine that you could have pumped air into the ABS unit, and it possibly needs to be cycled during bleeding to get the air out. Unfortunately, you need the correct diagnostic kit and software to cycle the ABS. I don't know if this applies to the 350z, but it certainly does/did to some ABS equipped cars when i used to do my own spannering! Hope my ramblings might help, Dave Quote Link to comment Share on other sites More sharing options...
daveparkin Posted September 3, 2012 Share Posted September 3, 2012 I've actually tried bleeding it with 2 people. the pedal stayed insanely spongy, completely drained, re filled and bled yet still spongy as hell, and when you push the pedal hard fluid drips out the bleed nipples. (not good) But without bleeding it enough to drive I can't even get it done at a garage. Be okay if the bleed nipples would just seal. Cross threaded a caliper yesterday, luckily I had a spare. Do you really mean drained, as in completey emptied the fluid out of the system? Quote Link to comment Share on other sites More sharing options...
tez162003 Posted September 3, 2012 Author Share Posted September 3, 2012 Yep, i mean completely drained, the car sat on the drive for a week with no calipers and a bottle collecting fluid on each corner. I bought new bleed nipples all round, and from my investigations today that seems to be the problem, the oe bleed nipples have a flat bottom on the end of the cone. The new ones had a very very small nib on the end, I think (fingers crossed thats the issue) Quote Link to comment Share on other sites More sharing options...
daveparkin Posted September 3, 2012 Share Posted September 3, 2012 For the bleeding, if you've let the system drain completely, you might very well still have air trapped in the master cylinder or the ABS module. Its always best if you can avoid letting air in at the top, but obviously sometimes you have no choice, e.g. master cylinder change. If you're changing calipers, better if you can prevent the loss of fluid completely, either by sealing the top of the reservoir to create an air lock, or blocking the hoses at the caliper end. As I said before hose clamps are effective, but you have to be careful not to damage the hose and cause a bigger problem than you started with. Anyhow, given that air has got in the top, the system will need a very big bleed. The two-man method was always my favourite - have you tried getting an assistant to pump the pedal (say 3-4 times) with the bleeders closed, then holding it down on the last stroke while you open the bleeders, and them ensuring that the pedal goes quickly to the floor? Then make sure they hold the pedal down while you retighten the nipples. I have always managed to get a good firm pedal like this, as it really flushes any trapped air pockets out. Also are you bleeding all 8 bleed nipples (i.e. 2 per caliper)? If you can get a pedal like this, you might then still need to get the ABS module cycled and bled again at a garage. I'm sure it goes without saying - don't drive it anywhere unless you are confident the brakes are working well. Hope this helps, Dave Quote Link to comment Share on other sites More sharing options...
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