Caliper Piston Cracked wide open

[ginandtonic]

Hey all,

I have the truck all back together after doing pads and rotors but while I had it apart I noticed the front passenger piston was cracked about 1/4 wide and maybe 1/2 deep into the piston. Of course, I said 'ah f*** yet another thing to fix, I'll do that next weekend', but then when I took the truck out after getting everything back together I had pretty substantial brake fade. As I would be sitting at a light the brake pedal would ever so slowly sink to the floor until it was on the floor and I'd have to let off and reapply with full pressure again. I was and always am very cautious with not putting tension on the brake lines so Im currently skeptical that its the lines, but could it be the piston causing this? I crawled under after and couldn't see any brake fluid, but I imagine it's just a pinhole, plus its dark and raining now.
Any help would be appreciated! As Murphys law would have it, we leave for a family camping trip on Saturday so Im hoping to get this taken care of tomorrow. I'm good to replace the caliper myself, but getting into replacing lines feels a bit out of my wheelhouse/comfort zone.

 

[Bigskyroadglide]

It's the same bleeding process so if you replace the caliper you still have to bleeding the air out, even if you clamp the brake line.

Unless you are seeing something really wrong with the line, just do the caliper. Go to harbor freight or auto zone and purchase one of those single person bleeding kit and take care of the problem.

I did lines and calipers in less than 2 hours working by myself in 95 degree weather outside.

Great chance to do a fluid flush as well, if you have time.

 

[turkeybird56]

U bleed all the lines after doing all? As far as caliper I personally would replace Neva want to goof off ref brakes. But would it cause brake fade dunno? U might have to bleed master cylinders also but u need to search there is a specific way to bleed system.

 

[bm02tj]

Never clamp or pinch a brake hose it makes it unsafe
And replace both calipers at same time

 

[ginandtonic]

U bleed all the lines after doing all? As far as caliper I personally would replace Neva want to goof off ref brakes. But would it cause brake fade dunno? U might have to bleed master cylinders also but u need to search there is a specific way to bleed system.

no, I just did rotors and pads so a bleed isn't necessary. I typically have shyed away from touching lines and fluid just because it's not something I'm experienced in and the risk is high, but I'll be spending the night learning how to bleed the system properly and replace a rotor, it sounds like.

 

[ginandtonic]

Never clamp or pinch a brake hose it makes it unsafe
And replace both calipers at same time

For sure. I was only doing rotors and pads so there wasn't any pinching of the line - I'm pretty cautious with how I hang the pad to not put any tension or twist on the line itself! Also, you sure about both calipers at the same time? I've heard that for lots of other parts but a caliper wasn't one of them!

 

[Bigskyroadglide]

Be prepared if the rotor has never been off, for it to be stubborn.

 

[BenchTest]

If you're getting pedal "fade" and aren't seeing any fluid, I'd check all 4 corners. Then check all 4 corners again. And if nothing, I'd be checking the lines front to back. Did you happen to check the fluid reservoir prior to compressing the pistons back into the caliper? If so, was it lower than what normal would be for extended pistons due to pad wear? Brake pedal fade is a tell-tale sign of an issue. The most obvious culprit is fluid loss, but can be caused by other items.

 

[ginandtonic]

Be prepared if the rotor has never been off, for it to be stubborn.

What?? I said I just did the rotors and pads and the problem is a cracked piston and the truck is all back together.

If you're getting pedal "fade" and aren't seeing any fluid, I'd check all 4 corners. Then check all 4 corners again. And if nothing, I'd be checking the lines front to back. Did you happen to check the fluid reservoir prior to compressing the pistons back into the caliper? If so, was it lower than what normal would be for extended pistons due to pad wear? Brake pedal fade is a tell-tale sign of an issue. The most obvious culprit is fluid loss, but can be caused by other items.

Shall do! I’d be surprised if it was the other corners since I was just doing the front but I’ll check. Unfortunately I didn’t check the fluid level before doing this as typically I see the process as separate from the whole fluid and lines system (just rotors and pads today). I’m gonna try replacing the Caliper with a cracked piston even though I’m not sure that a cracked piston could cause this :/

 

[Bigskyroadglide]

no, I just did rotors and pads so a bleed isn't necessary. I typically have shyed away from touching lines and fluid just because it's not something I'm experienced in and the risk is high, but I'll be spending the night learning how to bleed the system properly and replace a rotor, it sounds like.

Responded to last line of this post. Must have been a mistake

 

[BenchTest]

What?? I said I just did the rotors and pads and the problem is a cracked piston and the truck is all back together.

Shall do! I’d be surprised if it was the other corners since I was just doing the front but I’ll check. Unfortunately I didn’t check the fluid level before doing this as typically I see the process as separate from the whole fluid and lines system (just rotors and pads today). I’m gonna try replacing the Caliper with a cracked piston even though I’m not sure that a cracked piston could cause this :/

As brake pads wear, and the pistons extend in compensation for that wear, your reservoir fluid level drops. When you compress those pistons back into the caliper to install new pads, your reservoir fluid level increases (just stating this as part of the troubleshooting process I'm going through). That's why I asked if the level seemed "lower than normal" prior to starting the original brake replacement. For sure replace that caliper that is compromised with a broken piston. It's possible that fluid could be leaking by that piston, but that should be easy to discern with a visual inspection.

 

[Green_Manalishi]

It's the same bleeding process so if you replace the caliper you still have to bleeding the air out, even if you clamp the brake line.

Unless you are seeing something really wrong with the line, just do the caliper. Go to harbor freight or auto zone and purchase one of those single person bleeding kit and take care of the problem.

I did lines and calipers in less than 2 hours working by myself in 95 degree weather outside.

Great chance to do a fluid flush as well, if you have time.

Glad to hear it was cool while you tackled that project!

 

[Jeepwalker]

Chrysler (and others) have used phenolic pistons for years ....although I don't know for a fact what they used on your 2014. But that's what I suspect you have. Phenolic is a hard fibrous plastic like a bakelite. And on the phenolic's there's a metal cap, to help dissipate heat. Phenolics are great b/c they don't rot or rust up....which would tear up the o-ring inside the bore. The caliper probably didn't leak b/c the pads are worn enough the o-ring is on the other side of the damage.

My guess is some tech in the past took a pry bar or C-clamp to push the piston in (to gain enough clearance for brand new pads), and pried on the edge and that's what cracked it. I would bet money on it. I actually cracked the back side of one before doing something similar (my own stupidity and trying to take a shortcut). What I ended up doing was popping out the piston and just bought a new one. You can buy new phenolic pistons. This was on a 20yr old vehicle which the other piston looked like new yet! That's the nice thing about phenolics.

Most rebuilt auto part store calipers you buy will more than likely have a chrome-plated steel pistons, but it's worth asking when you go to get a new caliper. They're really not as good. The iron pistons transmit heat to the calipers (fluid) more (not good coming down long mountain passes), and they can rust/leak more due to corrosion. But for the most part, we're splitting hairs, overall, the steel works fine. But you can check with your parts store if they sell just one phonolic piston and swap it out (easy), or calipers with phenolic pistons (would be an OEM-like replacement) like the Amazon link below. A parts store around here can get a phenolic pistion usually overnight.

Generally speaking if you replaced the piston only, it would probably be a good idea to get a new boot and piston 0-ring, but a guy can almost always pop off the dust boot with a small screwdriver or a gasket scraper ...and retain the original o-ring and dust boot. Pop the pistons's out with compressed air (incrementally) with different thicknesses of wood between the piston and caliper ..and work them out in stages. And don't put your fingers in THERE lol. Or just replace the whole caliper.

More Information for CARLSON 7865

Amazon Caliper with Phenolic piston HERE

 

[jr27236]

" noticed the front passenger piston was cracked about 1/4 wide and maybe 1/2 deep into the piston"

WHAT! Who puts a truck or anything else back together after noticing this and thinks it's OK and on top of its asks if it's a problem. OMG obviously you need to let people who know what they are doing repair your vehicles for your family's sake.

 

[Jeepwalker]

I ended up crazy-gluing one...one time. And it's never broke. Bakelite takes super-glue really well. Or a guy could put some JB weld on it (if the cracked piece is still there). But I hate to recommend those things.

I know guys who say something is like 1/2", and the real measurement is closer to 2". Or it only takes 5 hours to get somewhere ...and it's more like 8. Lot of guys are loose with their measurements.... (no offense intended OP)

 

[Daw14]

Both front calipers should be replaced at the same time. What’s done on one side needs to happen onthe other side.

 

[Scottly]

10 years of absorbing moisture and dirt, all built up behind that caliper piston and seal, and when you compressed it back into the caliper, you pushed that square-cut seal over all that crud...and probably cut it. Go look and see if any of those calipers are now leaking. If they are, that's your fade.

 

[PolarisCobra]

Pedal fade can be caused by a bad master cylinder. You press the brake, the fluid leaks past the piston and back into the reservoir. No external leak, and releasing and pressing the brake pedal again gets things repressurized (for a bit).

Used to be easy to replace the master cylinder, but with the anti-lock assembly right after the master cylinder, it can be much more complex. You don't want to get ANY air into the Anti-lock valves. Pro shops have equipment to bleed that system, and can exercise the anti-lock system to clear the air out. Be careful if you need to get into this work.

 

[Jeepwalker]

Fade can be the result of a lot of things
- Excess moisture accumulated in brake fluid
- Cheap pads! (go to youtube and look up brake pad dyno test)
- Glazed pads and/or Rotors
- Worn other brake assemblies
- Ceramic pads ....where the application calls for Semi-metallic pads

Very unlikely it's the cracked piston. I'm putting my money on some monkey cracked it from doing something they shouldn't have (like prying on it...). I've been that monkey (just once though!). And I thought to myself an instant while I was doing it ...it was probably a terrible idea, right before it went "CRACK!". Otherwise they're pretty durable and long-lasting.

 

[ginandtonic]

" noticed the front passenger piston was cracked about 1/4 wide and maybe 1/2 deep into the piston"

WHAT! Who puts a truck or anything else back together after noticing this and thinks it's OK and on top of its asks if it's a problem. OMG obviously you need to let people who know what they are doing repair your vehicles for your family's sake.

... someone who is trying to save money by DIY'ing after spending way too much at the mechanic on numerous repairs (10k+ in the last 12 months)? wtf kind of comment is this? Obviously I was aware that a cracked cylinder isn't good. The cylinder was already cracked *when I took everything apart*. I had new pads and rotors in hand already and installed them, planning on replacing the caliper itself at a later date due to time constraints. After reassmbling, I had brake fade, however, I was not able to detect a leak as it was raining when I took the truck out. I was cautious, and the truck showed full ability to brake, with minimal brake "sponginess" at the start. It was only this morning that I realized that it was in fact the piston itself leaking fluid. Maybe try to take about 20% off the top of your emotional outbursts next time on an internet forum about trucks.

I ended up crazy-gluing one...one time. And it's never broke. Bakelite takes super-glue really well. Or a guy could put some JB weld on it (if the cracked piece is still there). But I hate to recommend those things.

I know guys who say something is like 1/2", and the real measurement is closer to 2". Or it only takes 5 hours to get somewhere ...and it's more like 8. Lot of guys are loose with their measurements.... (no offense intended OP)

haha, former framer here so I have my eye-ball measurements dialled in lol!

Fade can be the result of a lot of things
- Excess moisture accumulated in brake fluid
- Cheap pads! (go to youtube and look up brake pad dyno test)
- Glazed pads and/or Rotors
- Worn other brake assemblies
- Ceramic pads ....where the application calls for Semi-metallic pads

Very unlikely it's the cracked piston. I'm putting my money on some monkey cracked it from doing something they shouldn't have (like prying on it...). I've been that monkey (just once though!). And I thought to myself an instant while I was doing it ...it was probably a terrible idea, right before it went "CRACK!". Otherwise they're pretty durable and long-lasting.

I'd agree! The aluminum cover over the plastic piston was pretty damaged, so I'm think someone either pryed way too hard on it or bashed the caliper back over the pads with a hammer.