Calipers Stuck

[corbinenoble]

Purchased a 2009 M1123 off GovPlanet on December 9th with only 49 verified miles on it. Three weeks later my EUC was approved and I just had it delivered yesterday. The USMC left a file folder for it under the back seat that contained all the service info on it and why it was decommissioned. It belonged to MACG-38 and was fairly well taken care of. From everything I can tell, it simply just sat. The only real problem with it are the brakes pads are locked onto the rotors. It starts and moves under its own power although you can tell that the brakes are dragging and it will not move in the least when placed into drive unless given throttle. You can stop the truck but only with the very last 1/2 inch of the brake pedal. The brake pedal almost just sinks to the floor as if it’s not even there. I checked the fluid reservoir and have no loss of fluid. If it were just one caliper I’d isolate it to just that however all the brake pads around the truck are locked onto the rotors. Any common problems with these I should be looking for first before diving into cracking brake lines?

 

[juanprado]

symptoms you describe would cause me to first bleed all 4 ports in correct sequence and confirm you are getting fluid flowing out then trouble shoot from there. Sounds to me like a master cyl internally bypassing or proportioning/equalizing block problem. One caliper can be sticking but would not cause the pedal to go to the floor unless there is a massive leak of fluid or allot of air in the system. Might have 2 problems going on if there is contamination in the hydraulics like someone putting oil or atf in the wrong reservoir, it can mess up all the rubber components.

Other items to look at include is the parking brake adjusted correctly? Jack up each wheel independently to see what caliper(s) are locked up.

Just use basic brake troubleshooting.

 

[Mullaney]

Purchased a 2009 M1123 off GovPlanet on December 9th with only 49 verified miles on it. Three weeks later my EUC was approved and I just had it delivered yesterday. The USMC left a file folder for it under the back seat that contained all the service info on it and why it was decommissioned. It belonged to MACG-38 and was fairly well taken care of. From everything I can tell, it simply just sat. The only real problem with it are the brakes pads are locked onto the rotors. It starts and moves under its own power although you can tell that the brakes are dragging and it will not move in the least when placed into drive unless given throttle. You can stop the truck but only with the very last 1/2 inch of the brake pedal. The brake pedal almost just sinks to the floor as if it’s not even there. I checked the fluid reservoir and have no loss of fluid. If it were just one caliper I’d isolate it to just that however all the brake pads around the truck are locked onto the rotors. Any common problems with these I should be looking for first before diving into cracking brake lines?

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I'm not sure you should count on the 49 verified miles part of your statement. These trucks are not like your personal car where the government requires odometer certification. The speedometer doesn't even have to work... On the other hand, you may have a gem - but don't bet on it.

It would benefit you to replace every piece of rubber on and under the vehicle.

@juanprado just posted a comment as I was typing mine. Yep. Bleed it, furtherest bleeder away working toward the master cylinder. You may discover that you have grit and crud in the brake system. BE SURE to use the right fluid too - and not mix (for example) DOT 5 with DOT 3 or DOT 4.