Master Cylinder issue? Brakes seized up good

So about a month ago during a minor snow event I parked the truck for a few minutes and then when I restarted it the rear brakes were partially seized all of a sudden. I drove for a few hundred meters and eventually the brakes released.It never happened after that but I mentioned it to the tech after bringing it in for a service a few weeks ago and he couldn't find anything obviously wrong.

Well today, after parking the truck for a while doing some work, I got in, started it up, and the rear brakes were partially seized. Like the truck had to labour pretty hard to move the truck and it was slow. So I pulled over as I thought the e-brake was possibly stuck. I was told on these trucks you could tap the backing plate on the rear discs. Well that seemed to make things a little better but and things seemed kinda normal so I started driving and the brakes started slowly getting more and more seized until at a stop sign they just seized right up. Now when I say seize up, my rear brakes were taming all 236 HP under the hood. I was not moving, no where. I caved and just had her towed. The Tech at the dealership is very confident it is the master cylinder and it is being replaced. I'm just curious if anyone else has experienced this?

 

I think it's very unlikely the master would lock just the rears, but I guess it's possible. I'd be more inclined to look at something mechanically sticking in the rear brakes.

 

Do you flush the brake fluid on a regular interval? Its easy for any vehicle to have serious brake issues if the fluid isn't flushed. If you look in the brake reservoir and you see a cloudy or dirty looking fluid, then you've waited too long.

 

In each drum, there's a ratcheting automatic adjuster that moves the lower hinge of the brake shoes progressively closer to the drum, to compensate for shoe wear. Maybe the adjuster is broken and traveled all the way? How old is your truck and when was the last time you took it in for brake service (where they clean up inside the drum and apply anti-seize to all the joints)? It should be done every 2 years.

 

Most likely Not a Master Cylinder issue as stated above. It does indeed sound like the parking brake has seized.

 

Yes! But it was my front brakes. My truck is a 2010 Tacoma 2WD 2.7L/auto, purchased new in September 2009. I believe it had about 35,000-36,000 miles at the time of the incident in February 2014. Front brake pads had just been replaced in October 2013.

So, here's the story:

I was driving to college on a COLD morning in February 2014, and right after it snowed. I stopped for a red light at a 4-way intersection on a slight hill. The truck stopped just fine. The light turned green and the truck went absolutely nowhere when I took my foot off the brake and hit the gas. I could feel the rear wheels spinning around and the limited-slip differential kicking in, but the truck was going nowhere. Needless to say, I missed my class. Luckily my truck decided to become immobile right in front of some guy's house, and he invited me in to warm up and gave me hot chocolate. Anyway, this nice guy attempted to pull my Tacoma out of the road using his own older model V8 Tundra. While I was hitting the gas and he was pulling, he noticed that my front wheels were not spinning at all. AAA was called, and a local cop provided me with warning flares to place around my truck. It was determined that my front brake calipers were gripping the rotors and were stuck in that position.

My beloved truck was loaded onto a flatbed and hauled to the local Toyota dealer. One day and about $1,200 later, I got my truck back with a new master cylinder.

What happened:

When I applied the brakes, the push rod jammed and the front brakes remained applied. The techs dissected the master cylinder, a replace-only part, and discovered this. The service manager said this was a very rare (almost nonexistent) thing to go wrong. The truck had to be kept overnight because the part was not in stock.

It is now halfway through July, and my truck has not had any problems with the brakes since. In addition to the 1-year manufacturer warranty, the new master cylinder carries an additional 1-year of coverage exclusive to that dealer.

Your problem sounds identical to mine except your rear brakes had problems.

 

This would be my guess too, that or one or both of the rear brake cylinder pistons is seizing up. Third possibility is something in the master cylinder sticking as stated above.

I have seen the bolt/pin that slides the front caliper in and out get corroded and frozen on one vehicle, but that was on front disk brakes. Don't know how it got that way, I think my kids were driving it mostly at the time and got stuck in the mud one time. I assume water and mud got inside the boot covers or something.

 

$1200 for a master, WTF?!? You got screwed!
From memory: the front brakes are on the forward half of the master so they can stick, tho extremely rare, without the rears sticking. If the rear piston sticks in a master the front piston would also be pressed so all 4 brakes would be applied, again very rare. The master probably had a manufacturing defect that left a burr of metal that finally made it stick or something got into it while filling. Having the rears stuck after being parked like the OP would probably be the parking brake assuming it was applied. In this case, setting and releasing the brake will usually free it up or getting under the truck and wiggling the brake cables. After that it's likely going to stick again and get worse so it needs to be fixed asap. A master sticking might be freed by tapping the pedal a few times, but you'd have to be very careful driving from that point on and replace it asap.

 

Did you check that the E brake cable at it enters the rear drum is slack?? If the cable is rusted internally in its jacket it would appear the parking brake has released but the cable did not release at the shoes...