85 Ford 5yrd Dump truck, diesel, 5spd, hydraulic power assist breaks, one rear break hanging up? I have looked over the system and dont see anything obvious. Warning buzzer on breaks in irradically buzzing in cab sometimes goes off. It looks as if the hydraulic resevoir mounted on the front of the engine,(not the brake master cyl, but the hydrtaulic power brake assist system) is filled with a red liquid, is this right, looks like power steer fluid. Any Ideas, I just need to get it rolling so I can drive it into town from mountains to get brakes overhauled. Thanks
It sounds like you're describing a Lucas-Girling brake system. A couple of questions: Does it have a yellow Parking Brake knob on dash to the right of steering column? When you start the engine, does the warning buzzer continue to sound after engine has started and is running? Are you saying the parking brakes won't release after engine is running and you push yellow Parking Brake knob in?
Yeah that sounds like the system, yes yellow knob on dash for e brake, buzzer normally buzzes when truck is started but stops, not it is intermittetly buzzing, yes when yellow button is pushed in all brakes release except one rear whel which hangs up? Any Ideas?
Those trucks used a brake components system that was originally designed by Lucas-Girling and is now supported by Arvin Meritor under the product name DuraPark. The brake system is more about the rear brakes than the front because the DuraPark brakes provided not only service brakes but an effective spring applied parking brake as well. The bad part about the brake system is they can be a PITA to work on. The pump on the engine does two things, it provides hyd pressure for hydro boost assist for brake pedal, and it also provides hyd pressure to release the spring brake chamber on the durapark brakes at rear axle. The reservoir uses Dexron tranny fluid. If one of your rear brakes won't release, it would be a problem with either the parking brake wedge is not releasing brake shoes, or the adjuster wheel cylinder is seized and not releasing shoes. You'll likely have to back off the adjusters using the manual adjust wheel on top and bottom of adjuster cylinder. This is not going to be easy to do if there's considerable pressure on the brake shoes. If you know which wheel is stuck, I would chock the wheel on both sides, then wrench the 3/4" nut on the back of spring brake chamber until it pulls the spring brake all the way released, then attempt to back off the adjuster wheels on the adjuster cylinder. This is typically difficult to do because at least on of the holes in the backing plate for adjusting brake is right behind the axle leaf spring. If you can manage to back off the adjuster wheels and release the brake you might be able to get it to a service shop. Here's a link to the DuraPark brake so you'll have some idea what you're working on. ftp://164.106.79.2/Instructors/Rscoville/WABCO Meritor Brakes/Drum Brake HD.pdf