Caliper Failing? Symptoms?
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From: DFW
It usually takes more than engine heat and a few normal stops to boil brake fluid, no matter how much moisture is in it. Generally you have to be racing (not likely in a truck) or riding the brakes down a mountain.
Anyway, if you do boil your fluid... your brake system will accommodate. The fluid will just get pushed back into the master cylinder reservoir (unless of course you have adjusted your booster output rod such that the comp holes are blocked off by the seals). You don't even need to boil the fluid - just the thermodynamic expansion of the fluid in the calipers will be enough to apply the brakes if your booster rod has been adjusted out too far. (this is a fact - we've done the test, I've seen the data)
You would know right away if you boiled your fluid... on your next apply your brake pedal would go to the floor.
But still - a brake fluid flush could be helpful if you have contamination in your lines. Perhaps contamination is "trapping" pressure in your caliper by clogging the orifice where the flex line hooks up? (just a guess on my part)
Anyway, if you do boil your fluid... your brake system will accommodate. The fluid will just get pushed back into the master cylinder reservoir (unless of course you have adjusted your booster output rod such that the comp holes are blocked off by the seals). You don't even need to boil the fluid - just the thermodynamic expansion of the fluid in the calipers will be enough to apply the brakes if your booster rod has been adjusted out too far. (this is a fact - we've done the test, I've seen the data)
You would know right away if you boiled your fluid... on your next apply your brake pedal would go to the floor.
But still - a brake fluid flush could be helpful if you have contamination in your lines. Perhaps contamination is "trapping" pressure in your caliper by clogging the orifice where the flex line hooks up? (just a guess on my part)
I've also heard it stated that the flex line can trap pressure if it is failing. I do not understand it, and have never been given a clear explanation of how it happens. But some people will insist it happens and that they've seen it. So if you are going to bleed perhaps it would be a good time to put on some SS Flex lines?
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From: The Bluegrass State
...and the problem persists.
Took the caliper off tonight (for the third time) and one of the pistons WILL NOT move. I had to beat the thing off of the truck. Caliper replacement time.
Anyone have a decent 'how-to' on caliper replacement? I think it's easy... just don't want to screw it up and pull a bunch of air into the system.
Here's what I was thinking... correct if I'm wrong:
1. Remove old caliper by removing bolt securing brake line into unit.
2. Loosen new caliper bleed port.
3. Mount new caliper
4. Reattach brake line
Here's where I'm not sure... do I push in the pedal to bleed the brake line through the bleeder port or do I just leave it alone and allow it to bleed on its own?
Just a tad confused there.... other than that, I don't think this should be a really big deal. Thanks for the help.
-RP-
Took the caliper off tonight (for the third time) and one of the pistons WILL NOT move. I had to beat the thing off of the truck. Caliper replacement time.
Anyone have a decent 'how-to' on caliper replacement? I think it's easy... just don't want to screw it up and pull a bunch of air into the system.
Here's what I was thinking... correct if I'm wrong:
1. Remove old caliper by removing bolt securing brake line into unit.
2. Loosen new caliper bleed port.
3. Mount new caliper
4. Reattach brake line
Here's where I'm not sure... do I push in the pedal to bleed the brake line through the bleeder port or do I just leave it alone and allow it to bleed on its own?
Just a tad confused there.... other than that, I don't think this should be a really big deal. Thanks for the help.
-RP-
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From: The Bluegrass State
Ive had my both my caliper's changed now on mine because to the random sticking. Both of them were from the piston breaking/chipping and not allowing the piston to retract after the brakes were applied
This one was the worse out of the 2 but you can see the boot is torn on the top have causing the piston to bind and not retract
This one was the worse out of the 2 but you can see the boot is torn on the top have causing the piston to bind and not retract
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From: Joplin MO
Bleeding is a 2 person job. Top off the fluid, leave the bleeder screw closed, start the engine, have someone pump the pedal till it's firm, then HOLD it. Crack the screw loose, when the pedal hits the floor, close the screw and top off the fluid. Pump the pedal again, repeat till it stops spitting air when you crack the screw loose.
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From: Indiana
... or get a vacuum bleeder and pull the fluid out at the caliper. Can be quicker and is possible to do by yourself.
Caliper replacement isn't much more difficult than doing a brake job since you have to take the caliper off anyway.
2 things
- get a new copper washer for sealing against the caliper (and maybe new banjo bolts just in case they don't come out nicely)
- Make sure your bleed port is on TOP. Someone one the brake forum just made the mistake of putting the bleed ports on bottom. It don't work.
Good luck
oh, one more thing - if you do a pedal bleed... make sure you don't "bounce" the pedal against the floor. If the person pushes on the pedal too quick/hard it can bounce and suck a small amount of air back in.
Caliper replacement isn't much more difficult than doing a brake job since you have to take the caliper off anyway.
2 things
- get a new copper washer for sealing against the caliper (and maybe new banjo bolts just in case they don't come out nicely)
- Make sure your bleed port is on TOP. Someone one the brake forum just made the mistake of putting the bleed ports on bottom. It don't work.
Good luck
oh, one more thing - if you do a pedal bleed... make sure you don't "bounce" the pedal against the floor. If the person pushes on the pedal too quick/hard it can bounce and suck a small amount of air back in.
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From: Rochester, NY, USA
Brad,
Since you're going to crack the system open to replace one caliper, why don't you simply replace both? Based on the number of miles on your truck, it's about time anyway.
As to my thoughts on the process:
- Make sure you put the correct caliper on the correct side of the truck. The bleeder valve should face up.
- When bleeding the brakes, don't force the pedal down too fast. Gentle pressure works best here.
- Only use the correct slider lube as others have mentioned. Do not use Never Sieze.
- If the pads are worn or seriously rusted, replace them too.
- Call me if you need more advice.
Since you're going to crack the system open to replace one caliper, why don't you simply replace both? Based on the number of miles on your truck, it's about time anyway.
As to my thoughts on the process:
- Make sure you put the correct caliper on the correct side of the truck. The bleeder valve should face up.
- When bleeding the brakes, don't force the pedal down too fast. Gentle pressure works best here.
- Only use the correct slider lube as others have mentioned. Do not use Never Sieze.
- If the pads are worn or seriously rusted, replace them too.
- Call me if you need more advice.
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From: The Bluegrass State
Thanks for the words of advice, fellas. I managed to knock it out last night with the help of my neighbor.
(just got your VM, Tom. I had stepped away from my desk... thanks anyway for the help!!). BTW, the other caliper was replaced about 15k ago -- exact same problem but, I paid someone to do it. Also, you're right... I haven't done much with a brake system from a repair standpoint but, having a former mechanic (now in school working on his RN) next door certainly helps (especially when he works for beer).
The pads are better than 75% -- replaced them late summer.
The long and short -- all is well in Rockpick's Supercrew.
(just got your VM, Tom. I had stepped away from my desk... thanks anyway for the help!!). BTW, the other caliper was replaced about 15k ago -- exact same problem but, I paid someone to do it. Also, you're right... I haven't done much with a brake system from a repair standpoint but, having a former mechanic (now in school working on his RN) next door certainly helps (especially when he works for beer).
The pads are better than 75% -- replaced them late summer.The long and short -- all is well in Rockpick's Supercrew.
