Brake problem

[john493]

Guys - over the last 2 days I've replaced my strut top bearings, fitted new front disks & pads & replaced my brake fluid.
To push the front caliper pistons back, I clamped off the hose and let the excess fluid out of the bleed nipple.
Done this numerous times before with no problems on many cars.
I syringed-out the old fluid from the master cylinder, refilled with new DOT4 & bled it through with an easy-bleed kit at about 20psi, about 1 litre of new fluid used.
However I now have excessive brake pedal travel and very poor braking. By driving at low speed with the brake pedal pressed, it's clear from the disk temperatures that I've got no braking on the left front and right rear wheels - I guess I've lost a brake circuit.
I'm going to try bleeding it all again - but any thoughts on where I've gone wrong ? There's no easy access to T4 in these parts, but I can't see that I've let any air in :shrug:

Obviously car is not drivable until this is resolved.

Any suggestions ?

[oldcarguy]

Modern dual braking systems work by using one front and one rear brake on opposite sides, so it seems that you have air in one part of the system.
Can only suggest bleeding the two non working brakes again.

[mh007]

There was no need to clamp off any hoses or release any bleed nipples just to change the pads really.

As already said, you have air in the system & once you have introduced air, you'll need to bleed all around i'm afraid.

It's not uncommon to have air trapped in the master cylinder.

The 75/ZT can take a little while to bleed & i've had this on a few occasions.

Just keep bleeding & I tend to start with N/S/R, O/S/R, N/S/F then O/S/F.

This always works for me.

[john493]

I'm having another bleeding session this afternoon. Thanks for advice. I prefer not to push the old fluid back into the system by just pushing back the pistons when changing pads, (although when I used to use this method I never had any problems from it so I'm just being pedantic).

I'll try conventional bleeding using the brake pedal this time, see if that fixes it.

[john493]

All fixed now. I clamped off the brake hoses by the calipers, removed the bleed valve & wrapped plumbers PTFE tape round the threads to seal them. Then used a 100ml syringe (eBay) with some 5mm screen-washer plastic pipe to suck through the fluid. There was quite a bit of air in there - PTFE on the threads is essential else you just pull loads of air through the threads.

[mh007]

Well done John.

Glad you got it sorted.