wOrker

I recently went offroading. On my way home I definitely felt my brake pedal becoming more firm as I went along. I made a stop, and right after that stop my brakes started to lock up. Literally blasted my truck 4 hours offroad and then it does this on the highway.. Glad I was getting close to home.

Now I went to work this A.M. Completely locked up. All 4 corners. If the truck is cold it runs / brakes / pedal firmness is perfect - how it used to be.. once it gets hot. All hell. Front definitely hotter than the rear.. but the rear is locked too.

I checked the master cylinder, lines, etc. Everything is fine. It just seems all my calipers the pistons aren't retracting like they used to. So I took it to a local mechanic and they said to get all new rotors, calipers, and pads. I told them I only wanted the free inspection from the get go.. I think they wanted to tell me a price so I could roll my eyes? I dunno.. they wanted $2,200 for parts + labor. I laughed.

After that being said. I went to autozone bought some duralast calipers for all 4 corners, some grease for the slides, and all new pads.

Before I install the calipers. I want to try to C-Clamp the pistons back in and see where that gets me.. but are my old calipers completely shot? What goes into rebuilding them? (I can google this) Can I try to clamp all 4 calipers back, and bleed the system out then start from rear to front with my previous ones or is that a waste of time?

The only reason I had already bought the 4 calipers is cause 1) In stock 2) lifetime warranty 3) I can return them whenever with receipt

I need to get a quick fix - probably just going to install the duralast calipers I bought.. after I spray them red

Eventually I am going to upgrade to some 4 piston wilwood's but damn.. gotta get to work ya know?

snowborderus

Sounds more like a contaminated system to me. It's very very rare that ALL 4 CALIPERS lock up at the same time. (Have you had any work done recently?)

If it is just locked up calipers, replace them and be done with it. Don't worry about rebuilding them.

That shop wanting $2200 for full brakes is ridiculous. Where I work, we could easily do for about half that.

wOrker

I know right. It's seriously weird that literally all 4 calipers are locked. On the lift I couldn't even spin my tires with my hand..

I'm just going to replace all the calipers and pads, bleed the thing out - put some fresh brake fluid in there.

snowborderus

If you can, get the brake fluid tested for contamination first. I'd hate to see you replace everything on a contaminated system and the problem come back in a bit.

wOrker

Where can I go about doing that? I know the brake fluid is pretty dark.. it definitely needs to be flushed, that's for sure.

I really don't see how all 4 pistons go bad at the same time. That's what's blowing my mind.

I don't know everything about brakes. But is there a bleed valve on the master cyl that releases the calipers if opened up? Or do I try to bleed each individual caliper to see if it'll open up?

wOrker

Today I flushed the system (brake fluid was relatively clean from what I noticed). I did the rear to the front calipers and pads.

Here are some pictures of what my calipers looked like..






I've changed them all out, bled the system correctly, yet still the problem persists.. they're locking up.

Someone at autozone said the ABS system could have had something happen to where they lock up. Except, no brake light, no codes. I have no idea.. I don't think it's ABS. I've google'd this to death. Blah blah brake lines, flex lines, etc. My lines are 100%, are extended brake lines, and are beefy. They handled.

I don't want these new calipers get screwed up..

The vacuum line to the brake booster is working fine. The reservoir to the master cylinder is wobbly about 1" on the gromits.. that isn't normal.. I bought a new master cylinder but haven't installed it yet.. I checked the brake sensors, brake lines.. fluid is running through solid, sensors are clean and fine..

What gives!?

PerryB

It has to be a seized master cylinder. Probably the rear piston. If it cant retract the front one cant retract and all four corners will hold pressure.

snowborderus

If you have a contaminated system (any brake shop should be able to test for you) it will cause ALL of the rubber components to swell. Any rubber part in your brake system will become so swollen that they won't let brake fluid pass through. Brake lines, abs unit, master cylinder, calipers, they all have rubber parts. There is no "release valve" for excessive pressure. If it is contaminated you'll need to replace everything with rubber in it and flush the system with an cleaner, not just fluid.

wOrker

Replaced the master cylinder this AM. It was the culprit! I did need to change the calipers obviously as well so I'm glad I did that.

I flushed the system with brake fluid. It's bleeding out all 4 corners clean and smooth now. I don't believe I had a contaminated system. I just believe my master cylinder got jarred or something happened internally that caused it to start locking up and not retracting.

wOrker

Drove to work.. brakes are getting stiff again.. felt it definitely when trying to park. The heat off the calipers is not as bad as before.. the rear didn't feel any noticeable heat. The front was rather warm.

Going to check after work and do some more testing. Going to buy a brake booster at lunch.. my next thought is the brake booster is holding vacuum but the pin itself that pushes the master cylinder in is not retracting? the pressure is holding it in place? No idea...

Going to recheck all the lines.. maybe a rock dented one of the main lines.. considering now it's only the front sticking.. but I can't be 100% sure till I check it at home.