I was hauling a load of scrap metal to the recycler last week with my F600 and the farther I drove the harder the truck pulled. After about 8 miles I pulled over to check for a problem as my speed was really falling off. I had light smoke coming from the rear wheels. The trucks brakes were locked and would not move at all in any gear. I investigated and found the rear wheel backing plates were hot to the touch. Front brakes were a little warm but nothing like the rear. Suspected a collapsed rear hose......so we bled the rear line and went on our way. About seven miles later......same condition. Same remedy, added some fluid and drove home empty and only used the brakes once so no problems. I replaced the rear hose with a new one from NAPA and hauled a load of logs to a saw mill this week. Upon arrival the brakes had me locked down again. No major heat but the brakes would not release until we bled the rear line again. What is my problem? Another hose? Booster? Master Cyl? Thanks in advance for any help!

 

I would start like this

Look for any obvious mechanical issues with the brake itself... seized wheel cylinder...since it was pulling I would be extra suspicious of that side.. check for frozen shoes (although doubtful)...or completely worn out and siezed .. again usually you would hear this and feel it..


Then I would move to the master cylinder.. disconnect the brake line... pedal it and inspect for good clear stream... and return,,, the return stroke is important because you want to make sure its not applying continuous pressure

Then I would be suspicious of the master cylinder

180 new at Oriellys
100 or so reman'd...

If neither of the above I would go to the booster.. but.. I doubt it.. normally they just fail and dont apply pressure all the time.. possible but not probable.. in my experience.. normally if you pop the vacuum line and you hear vacuum its usually ok

Again.. Napa or Orielly.. Cardone does them as remans

On all three of my f600s I replaced the master cyinder.. just from sitting for years before I got them they all had issues....

I wouldnt suspect a hose..Ive had them break but never collapse

 

I have a 83 F-700, started replacing all the brake lines last weekend(replacing with Nicol/copper lines) when replacing the line from the master cylinder(single system) to the brake booster, about 20" below the MC, the line had a rubber(flex section) about 8" long,that we couldn't even see, it was inside a conduit/chaseway at the bottom of the inner fender, near the clutch linkage, just a thought you might want to know or look at your truck.
We had a car (01' Taurus) that was having brake issues, front pass side kept locking up when driving down the road, changed the flex brake line and the anti lock short wiring harness fixed the problem, not sure which one was the issue,, flex line looked over crimped or bent, at the mount, harness looked burnt/melted.

 

Thanks for the replies! I will look into all issues mentioned. Today I noticed some brake fluid has leaked on the right front wheel. They are Daytons so it fell to the outside. I will look into that first. Unfortunately my rotating shift work schedule will prevent me from getting into this for about 10 days. Again.....thanks for the experiences!

 

Aught oh...

brake line or wheel cylinder

I doubt its leaking from the master and traveling all the way down the line


Good luck

 

I do not want to sound too closed minded, but your issue is in the booster. A few years ago had some less than perfect brakes with my 67 C600. So replaced rear drums, shoes, a couple of slave cylinders, master cylinder and finally replaced the booster with a rebuilt unit. All went well for about six months until while hauling gravel from 2000 feet to 6000 feet the brakes would come on about half way up the hill. Bleeding the brakes was the only way I could get the thing to move. This process became a routine. Not wanting to just keep dumping money into the thing I started digging. Soon I noticed the booster was a rebuilt unit with new seals. After some work I determined that it could leak a little. So went to the wrecking yard and found some better shafts and such. After several attempts it has been very reliable. Thanks

 

Thanks TJ. About 40 years ago I was hauling bagged fertilizer for my grandfather's business and had a similar problem with a 1965 C-60 Chevy. The pedal became stiff and brakes would lock. I thought I remembered it to be the booster........but time changes things and I was not certain.