Front calipers keep locking up

I've got a 2001 1st gen v8 4x4 and about 2 years ago I changed the calipers because one was sticking. About 3 months ago the passenger side seized completely, I only changed that side. Now they are both seized. I can't find a single leak anywhere in the lines and they had been bled properly and worked perfectly up until the point of siezing. I know I should've change them both but why do they keep prematurely seizing?

 

I’d change the hoses too. They can fail internally and act like a check valve.

 

I'm no brake expert, at all. Take everything I say with a grain of salt.

Is it possible there's crud in the brake system? Debris?

 

Didn't know this.

I changed mine in December to Wheelers stainless steel.

 

Did you grease the slide pins and the slides between the caliper and brake pad ears?

 

A pedal pushrod that’s adjusted too long (if adjustable) so the master cylinder doesn’t fully return, or a plugged return port in the master cylinder can also hold pressure in the calipers and make it appear that they are seized. Crack the bleeder open and see if any pressure releases.

Did you flush new fluid into the system when you replaced the calipers? DOT 3 /4 absorbs moisture over time, and becomes corrosive as that happens.

Where are you getting your parts? What brand? There are lots of terrible remans on the market too.

 

I changed mine on my Sequoia just to upgrade while figuring out a brake issue I had.
STOP TECH 95044007

$46 StopTech 950.44007 StopTech Stainless Steel Front Brake lines for 95-07 Toyota 4 Runner

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I've had 3 calipers seize on me. Thankfully they are lifetime warranty from Oreilly's. The pistons don't seem to seal well and get stuck in their bores. This set has lasted me a couple years thankfully.

 

Once you pick up a hammer every problem looks like a nail.

The brakes on my grandpas truck drug, the pads and rotors were glazed, sometimes they would drag, sometimes they wouldnt.

i did powerstop pads and rotors, that come with new pins and clips, and found the original pins worn way out, so i filed the edges if the calipers, where the pads ride, smooth. I replaced all the rubber hoses, because truck is 19 years old, and the master cylinder.

I could feel through the pedal (by hand) that the master cylinder was hanging up about 1/2 way down, so i gave the master cylinder a sharp whack with a small hammer, and it fixed it, but not permanently. So swapped the master cylinder, wrung my hands worrying about a non issue with the brake booster, and its been great ever since.

 

If you find that it isn't the calipers or brake lines you might check the brake proportioning valve.

 

Where do you live? Different vehicle but same brakes; I had this trouble with my 3rd Gen 4Runner Tundra brake upgrade when my kids lived near the coast = excessive corrosion. Also, their driving habits weren't hard enough on the front brakes to keep the pistons moving enough.

 

So I have always properly greased them, the first set was nappa, the 2nd one was some after market from oreillys. I always flush and bleed. I have changed the bent line going strait to the caliper and the rubber line going up past that but no lines to the booster or master cylinder. Thanks for all the input I just changed all calipers rotors and pads, and I will now change the lines leading up until them at the least

 

My right front brake was dragging I thought it was the caliper turned out be the brake pads were seized in the caliper. I shorted the pads with a big file and now they work great.