Pushing back calliper pistons

[shogunswb]

Need to change the pads & discs on the rear of my sons IS220d 2008 & just wanted to check that it's ok to push the pistons back without loosening the bleed valve so that the fluid drains out rather than being pushed back through the ABS.

The reason I ask is because with my Mitsi Shogun (& a few others) if you push the fluid back through the ABS it knackers it & obviously I don't want to do that.

Also any tips or problems that I should be aware of when doing the job(I know about the seized pins from other threads).

Thanks

[leelacey17]

I have the is250 and I simply loosened the cap off the reservoir and slowly pushed mine back in. Haven't had any issues at all.

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[normski2]

+1 to the words above.

Precisely what I did...I also syringed off a little oil from the reservoir to avoid the chance of any spill out. I still wrapped an old towel around the underside of the pot ... just in case!! I used a block of 2x1 and a G clamp to push the piston back ...no particular reason ... just found it easier that way.

I did the same task recently...here

May give you a few pointers

[Texas]

Screw thread 'G' clamp or 'Kwlk Clamp' will work fine but what ever you use do it real slow, there is no rush needed in this task and although I have heard of problems 'pushing the fluid back into the master cylinder' causing seals to 'flip' and then braking system problems, I personally never had any problems but it might be down to doing it sloooooow!

[steve2006]

Surely it is far easier to slacken off the caliper bleed nipple, fit a suitable piece of plastic tube over the nipple into a container then gently push back the pistons rather than risk seal damage further up the system?

[Texas]

+1 on loosening the bleed nipple method for various reasons,

1 it periodically ensures the nipple is not siezed!

2 if the flexi brake hose is suitable clamped then fluid cannot be 'pushed back into master cylinder'

3 it allows a small amount of brake fluid to be removed ( master cylinder will therefore need topping up afterwards) and it will be the fluid that has been living and working in the most hostile environment and exposed to extremes of temperatures so this will be a good thing.

paul m.

[shogunswb]

Thanks everyone.

I think I will try to loosen the nipple & do it that way to be on the safe side but if not at least I know that I can push the pistons back without fear or causing damage to the ABS system.

[shogunswb]

Bit of a problem has now occurred.

Before touching the brakes it had a very long brake pedal but had recently been through an MOT, a courtesy test at Lexus & a service where they tested it again on the brake balance rollers & all ok or so it seemed.

Anyway got new rear disks & pads & drivers side was partially seized with the pad on the piston side down to metal & the other one two thirds worn but cleaned it all up re-greased & reassembled with new disk & pads no problem & bled the calliper to make sure.

Passenger side was fully seized & required heat & quite a few blows with a club hammer to remove but again all cleaned up & re-assembled ok with new parts & bled the calliper.

Problem is that now the brake pedal goes to the floor on he first push but ok on the second push & yes we did pump the pedal first to take up the slack on the new pads.

Took it for a little test drive with a little bit of left foot braking & all disk started to blue up so all the callipers are working ok in terms of pushing the pads onto the disks but it would appear that the callipers are retreating too far when the pressure is released.

Anyone come across this before or got any suggestions?

[Texas]

Are you sure that there is not any air in the system. Air will compress and it sounds like it is with the first pedal push and then the second won't compress the air any more and the hydraulics work. 

Paul m.

[Britprius]

This sounds more like air in the system than any other fault.

John.

[shogunswb]

It doesn’t feel like air because the pedal isn’t spongy.  It feels more like badly adjusted drum brakes where it takes the first push of the pedal to move the shoes onto the drum then the second push is needed to apply pressure.

Having said that we are going to try & get the Techstream software & bleed the brakes using that.