changed front brakes on silverado. did I screw up?

[Dennis McAtee]

On one side I put the pistons back in without opening the bleeder valve. Turns out both valves will not move anyway. I remembered eric saying to loosen the hose if that happens and bleed it that way. I did that for the other side. It seems to work ok, it stops anyway. What can happen if you put the piston back in w/o bleeding it?

Topic

[Tom]

Theoretically, you can damage the master cylinder.

I have reset brake pistons without opening the bleeder valve for years, and never had any problems with my master cylinder after doing so, but that doesn’t mean it can’t happen.

[Gumpy Guss]

Hmm, well Eric’s idea is an ingenious one, but not quite 100% perfectomundo. Bubbles always float to the top, so that’s why the bleed screw is always at the topmost point of the caliper. The banjo or screw fitting is usually NOT quite so high, so even if you bleed through that, you will get some air out but probably only get about 70% of the air out.

I suggest you dismount the caliper again, drain out the fluid, heat it up with a propane torch and use a 6-point socket to unscrew the bleed screw. And replace it with a new bleed screw, as you’ve now annealed it into the consistency of 5 year old bubble gum.

[Shaun Flichel]

you will be fine. your brakes, especially the rear shoes push fluid back to the master cylinder anyway. of course not as much as fully compressing a caliper. just go slow

[Bill]

I have never had or seen a problem with pushing back the pistons without opening the bleeders but the potential for problems is there.

[Tom]

Someone posted a link to a tool a while back which is essentially a socket adapter on an air hammer. The idea is you use a hand wrench to do the turning, and the air hammer / chisel to shake the fastener loose. The manufacturer showed it being used to loosen a bleeder screw that was rusted to crap on an ages old VW beetle brake that had been laying about outside in the yard for years.

That might be worth a go on your stuck bleeder screw. Otherwise, heat, penetrating oil, and a 6 point socket are your best hope for getting it open, then wire brush it clean, and give it a bit of never seize, and away you go.

[Kevin Criswell]

[quote=”wysetech” post=76166]I have never had or seen a problem with pushing back the pistons without opening the bleeders but the potential for problems is there.[/quote]

Same here, for years I never bothered with opening the bleeder, but a friend of mine did have some issues with the old Keesly-hayes combination master cylinder/ABS using pushing fluid back in. I switched to using the bleeder method “better safe than out money” philosophy.

[drthrift035]

I understand why Eric uses this method. However in a Shop environment when people are on flat rate it would take too much time. Also using Eric’s method you have to be prepared for the caliper bleeder screw to get stuck and be ready to change the caliper if that happens.

[cunno96]

if i remember right the reason you crack the bleeder when pushing the piston in is to not damage the abs unit as it can damages the internals you can get away with loosening the hose but if air gets in it will effect the breaking how badly depends on the amount of air in there

i personaly would not use heat to loosen the bleeder as this may warp the metal affecting the clearenses

[Dennis McAtee]

Thanks, now I just hope for no air til I get a chance to fix the valves.

[Author]

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