storx

today i droove out to a friends place to help him tow something and on the way back i stop and the truck seemed like it had a load on it taking off due to massive amounts of black smoke off the takeoff.. so i went home and jacked the truck up and both front tires i couldnt turn them and they were blistering hot i couldnt touch the rim even...... so i took the calipers off and i pushed them all the way in greased up the caliper a little and reinstalled the brakes cause they were pretty much only half worn... and the truck still does it.. it drags the front brakes lightly once u drive a few miles u hear them stop dragging probably from wearing down the pads tell it clears the drum.. but anyone have any ideas im not an brake expert...

storx

oh ya i just wanted to add to it.. when you drive the truck it stops perfect no soft touch at all of the pedal.... also last few months before this happen the brakes would be very touchy when u first turn the truck on and when you droove down the road a little they would work perfect.....

bamadzl

My truck does this too. I'd also like to hear some opinions.

Brad

dan239

Since no one else seems to want to respond I will give you one option. The problem is likely in the adjustment of the master cylinder. The piston is not returning far enough to allow the fluid to feed back and release the caliper.

Daniel

storx

well i droove it over to my buddy's house cause he knew more about the brake system then i do. So we tested some things out i didnt know about. If you pumped the brakes down where they are sticking nice and noticable you undue the brake line you can see if its the caliper or not by if the caliper releases and works normal. so we did that.. both sides release how there suppose to. Then we went to the central brake cable that leads into the valve that suppose to control the rear brakes from locking up and undid the line and the calipers again unlocked. so this point we are pretty sure its the master cylinder thats the problem. because from what we can understand the brake booster just used vacuum to make it where you dont have to stomp on the brakes for them to brake just a little bit. In theory gives you power assisted brakes via hydraulic preassure.....so im doing research on a cheap place to get MC, auto parts store had it 140.00 at autozone and 72.00 at advance but advance one doesnt come with new brake fluid container so im not sure how hard it be to transfer the container over.

dan239

I am sure the master cylinder can be adjusted but I am not familiar with this particular one to tell you how.

Daniel

dan239

When I said I was sure the master cylinder can be adjusted, I was referring to the push rod from the brake pedal. I was not able to confirm this in the service manual [service manuals are not what they once were].

This may sound silly, but have you tried pulling up on the brake pedal to see if the brakes will release.

If your problem is between the master cylinder and the brake pedal, a new master cylinder will not fix it.

Daniel

storx

actually that was the very first thing i checked because the mercedes tends to hang up from time to time requireing you to put a little grease on the lever to loosen it up...

bamadzl

I can pull "up" on the brake pedel with my foot and the brake will release. It's been doing it for a while now. I thought it was a sticking caliper. Anyone have any idea what I should look at to fix this.

Brad

dan239

If your brakes release when you pull up on the brake pedal, it means the pedal rod is keeping the master cylinder from returning to the released position. It could be the pedal is sticking or the rod is too long. The rods were adjustable many years ago but I do not know about these trucks.

Pulling up on the pedal would not effect a sticking caliper. The caliper is opened up by the friction of the disk.

Daniel

bamadzl

Thanks, I'll check it out.

Brad

yfz450guy

could it be the case if the pedal is not returning to the top that the return spring needs to be replaced? just a thought.