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Can you push caliper piston too far back in??

Mossyoakglock

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jdnoble18 Enthusiast

jdnoble18

Posted
Posted

There is some way to reset that ABS unit. The guy at the parts house was telling me how to do it but I didnt pay much attention, something about pumping the pedal 20 times with the truck off? Might be worth looking into.

  • 1 month later...
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lostkiwi New Member

lostkiwi

Posted
Posted

I have exactly the same problem with my 07 Siera 1500 as Jerry Noble describes above.

I have tried for over an hour to bleed the air out but the air bubbles are constant and not just tiny bubbles but big ones.

Ive tried a gravity bleed as well for over an hour with no luck either.

I just cant think of where all this air is coming from.

 

Could I have gunk stuck under a MC cup thats allowing air into the system each time the brake is pushed?

Maybe the gunk could have got there when I pushed the pistons back?

 

I was thinking next of bleeding the MC for the front wheels as I think the problem is still localised there.

Alternatively I was thinking of a bench bleed until I saw Jerry Noble's mention of just doing a pressure bleed to sort it out.

Jerry, do you think this would work for me?

Also when you say pressure bleed do you mean bleed from mc down or caliper up?

Cheers!

lostkiwi New Member

lostkiwi

Posted
Posted

Good Question.....

 

I guess Ive experienced too too many huge quotes including unnecessary parts from Garages for work that I then completed myself correctly at a fraction of the cost, after abit of research.

 

I also like to think that because its my vehicle and life at stake that I will be more careful to do it right than maybe a young mechanic doing the job as quick as he can to keep in favor with his boss.

  • 2 weeks later...
  • 2 weeks later...
amc31b Enthusiast

amc31b

Posted
Posted

Well, replaced the MC and now all is good.

 

Glad you got it fixed! I have seen this happen quite a few times actually. By not opening the bleeder valve on the caliper, you put excessive pressure on the seals inside the master cylinder and trashed it. This also happens alot during brake jobs, when guys use the old way technique for pushing pistons back in. Opening the MC cap and pushing old brake fluid upstream is bad news for the ONE way seals inside the MC. Pushing the piston back the old way frequently results in a mushy brake pedal but I have also seen the master cylinder leak and fail completely.

 

When pushing pistons back in, leave the MC Cap on, crack the bleeder valve and then push the pistons back in slowly and consistently until they stop firmly. Do not force the piston back as hard as you can, firm pressure is all you need. Close the bleeder when the piston stops and you will have no problems. The best news about this technique is that besides not pushing the brake fluid in a direction it was never designed to travel, you also remove the hardest worked fluid in the whole system, the fluid at the caliper and brake line.

 

I usually suck the old brake fluid out of the MC reservoir before I do this and then bleed the brakes a few times after the pads are on, just for good measure. I have never had any problems or a spongy pedal, even when using cheap pads and rotors.

  • 3 weeks later...
KK2000 New Member

KK2000

Posted
Posted

I just put new front rotors & pads on a 2000 1500. I had to retract the pistons on mine pretty good but didn't have to bleed anything, All I did was take the cap off the master cylinder while compressing. No problems.

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