I am in the process of replacing the pads and followed one of the guides on here, thank you

I took the top off the master cylinder whilst I was pushing the piston back but got rather confused when the level of fluid didn't change

Is there something secondary inside that needs to be removed to see the true level?

It’s ages since I did mine but there’s a bell ringing about screwing the pistons in.

I did this a few weeks ago. The change in fluid level in the reservoir was barely measurable after i pushed the pistons back. I'd say it's normal.

Excellent thank you for confirming

I was told that its illogical to push old fluid back towards the master cylinder. Instead you should open the bleed valve and drain it out there as you push back the pistons. The pistons move much more easily too.
No chance of an overflow at the master cylinder end either as you can see the fluid being pushed out whilst pushing the pistons. Jules

Agreed .... per this video

I normally push it back, in my head there is less chance of allowing air in that way.

I did front and rear pads at the same time recently asking with me rear discs and the level did creep up. I ended up taking some of of the reservoir with a syringe. Just changing one pair made no difference.

I guess it will only show up like that if someone topped the fluid up between the brakes being changed.

Not really - you're not taking the bleed valve out, just cracking it open - just like you would when you bleed the brakes and pressurise the system from the master cylinder instead of via the brake cylinder as in this case. Jules

It's very bad practice to reverse the fluid flow of a vehicle with ABS. It's too easy to damage the valves inside the modulator, which would then be rendered scrap.

The correct way to do a pad change is to clamp the flexy hose with a brake hose clamp (Mole grips used carefully will also work), fit a brake bleed tube, and release the bleed screw ¼ of a turn. At this point it's safe to push the piston back in, and the fluid displaced goes out the bleed screw, and not back up to the modulator. The bleed screw is then tightened back up, and the clamp can be removed.

At the dealer I worked at (not LR), any technicians caught pushing fluid back up to the master cylinder, would have been disciplined, as the vehicle manufacture was very strict on taking such short cuts, and wouldn't honour any warranty claims for damage caused by reverse flowing the brake fluid. 2009 Rimini Red SE TD4. Soon to be sold.
Hyundai Ionic 5 Ultimate on order.
Gone. 2006 Tonga Green i6 HSE.

I assume the brake needs to be bled after taking the clamp off

Not because you've used a clamp; it should not allow any air into the system. But I would because you might as well flush clean brake fluid through the system whilst all the kit is an place and you are going to have to top up at the master cylinder anyway as the pistons move back out. Jules

Last edited by jules on 21st Jun 2022 10:33 am. Edited 1 time in total

As above. There no need to bleed, as no air can get in. However it makes sense to bleed brakes, so cleaner fluid makes it's way to the rear. The BF should be fully replaced every 3 years, so the time to do it is when the pads are being replaced. 2009 Rimini Red SE TD4. Soon to be sold.
Hyundai Ionic 5 Ultimate on order.
Gone. 2006 Tonga Green i6 HSE.