2nd Gen Non-Engine/Transmission brakes lock while driving around

[Berserker]

I've done the searches and this doesn't appear to have come up before so here goes...



A couple of days ago I leave my house in the morning, drive about 5 miles in stop and go rural roads and I notice that it's like something is holding the truck back. Usually you let off the brake pedal and the truck starts to move forward pretty easily. Not so - and it started getting worse. I turned around and headed home and it progressively got worse until I felt like I was having to power my way home, brakes locked the entire way.



I let everything cool down (front wheels were very hot) and tried again. This time it took just about all the power the Cummins could muster just to back up. Laying rubber almost the entire time in reverse! Eventuall I just started going forward again and made it home - powering through the brakes the entire time.



I took off the master cylinder today, drained the resevoir and used a screwdriver to depress the plunger. Brake fluid comes out easily through the brake line holes. I put 2 fingers over the holes and released the plunger and I felt a vacuum. My friends don't think it's the master cylinder. Sitting in the cab, I depress the brake pedal, the plunger of the Hydro Booster comes out. When I release the pedal it moves back in - easily.



What could it be? I do have SS Brake lines. I know that's not a guaranty against an internal collapse but it's better than the usual rubber lines.



Any ideas are appreciated.

 

[nutter3]

Sounds like the wheel cylinders, but it is strange that both front cylinders would freeze up at the same time. Were the rear brakes hot too?

 

[NIsaacs]

Did you change the master cylinder recently? It sounds like it is not quite releasing all the way. Leave it loose on the booster, about 1/16" and try it. If it is free then bolt it tight again. If it is locked up again, I would say the booster rod is a little too long and would need adjusted a little shorter.



Nick

 

[ttbird]

Sounds like the flex hose at wheels from hard line to wheel caliper. The inside of the hose deteriorates and closes down, not letting brake fluid flow back to resevoir, locking up brakes

 

[JTruelove]

I had this same issue. When I turned off the truck then re-started it would go away. I ended up swapping out the rear drums to OEM disks and have not had a problem since.

 

[Bill Lins]

Had the same problem with a 2000 Dakota. The pistons were sticking in their bores in the front calipers- wound up replacing both calipers & problem solved.

 

[JMcCoy]

Sounds like the wheel cylinders, but it is strange that both front cylinders would freeze up at the same time. Were the rear brakes hot too?

There are no wheel cylinders in the front. It sounds like the calipers are sticking. If the calipers are not too old, I would remove and inspect them. If they look ok, fully collaps, lube and reinstall them. Make sure you lube the pins real good with proper lube. See how they act then. Good luck

 

[ETavernier]

Berserker,

I had a similar problem on my previous '98 when the pads were very worn. One of the caliper pistons would not release. Removing the caliper and using a big C clamp to compress the piston into the bore, I replaced the pads on both sides and never had another problem... .

eddie

 

[JKinney]

Sounds like the flex hose at wheels from hard line to wheel caliper. The inside of the hose deteriorates and closes down, not letting brake fluid flow back to resevoir, locking up brakes

Ditto They actually get a break down between the hose plies and that collapses the hose, and does not let the presure back off. If your brakes lock up again get out and wiggle the hose and you will see that your brakes are free. Just replace the hoses, easy fix.

 

[ewcmr2]

Open the bleeder screws before you push the pistons back in. That way you won't push dirty old fluid up into the ABS and/or master cylinder.

 

[Berserker]

Thanks for the responses. I can only work on my truck during weekends but it's all figured out.



Essentially the last shop that I brought my truck to must have used contaminated brake fluid. I am having to replace every single piece of rubber in the braking system front to back! Even the freaking brake fluid cap boot is all $%&!@# up! This even means new calipers (replaced about 10K miles ago!).



I'm going to that shop this week with all the parts to see what they will do about it.