No brakes when engine off
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Senior User
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No brakes when engine off
My 76 F350 1 ton dump has NOOOOOOO brakes when the engine is off. Its a 4 speed with a 390 in it. The brakes work good when the truck is running but if I shut it off on a grade it just rolls until it hits something and can't be stopped with the brakes. The other trucks I own or owned were all automatics and even with key off I could drift and stop them no problem. Whats the deal and whats the problem here? As usual any and all comments welcomed. Thanks.
Elder User
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do you have power brakes? if so i do know it is hard as heck to apply the brakes
when the engine is off due to it takes vaccuum to work the brakes.
but second question is does the pedal go to the floor when you are trying to apply the brake?
and does the e brake work?
when the engine is off due to it takes vaccuum to work the brakes.
but second question is does the pedal go to the floor when you are trying to apply the brake?
and does the e brake work?
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Yes they are power brakes and yes the pedal goes to the floor. I know what you mean about it being hard to brake when the truck isn't running, but its still do-able.
No E-brake yet. I'm waiting on the equalizer to come in. This is the first old manual that I've had, so still trying to figure out what it can and can't do. Braking (not breaking) is one of the things I think it should do. LOL. I'm not sure if the previous owner put the right master cylinder on. It looks like the one on my F150 and I know there are different ones for these F350's.
No E-brake yet. I'm waiting on the equalizer to come in. This is the first old manual that I've had, so still trying to figure out what it can and can't do. Braking (not breaking) is one of the things I think it should do. LOL. I'm not sure if the previous owner put the right master cylinder on. It looks like the one on my F150 and I know there are different ones for these F350's.
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We've got a '76 F350, 390, 4 speed, but ours is a tow truck. The brakes, power assist or not, should work with the truck off. If the pedal goes to the floor, that's a problem. There should be pedal, truck running or not. How much pedal do you have when the truck's running? Not to insult you or anything, but is the master cylinder full? Are there any leaks? System bleed correctly? Any one of those things would cause the brakes not to work. Being power assisted, you may not notice low brake fluid, small leaks, or a little air in the system with the truck running. If not, the rod on the brake booster may need an adjustment. Those little buggers are tricky to get just right (played with ours for about an hour and half when we first got it). If it's not set right, it's not going to actuate the master cylinder correctly. I've also had some problems with the proportionate valve that have caused some strange things to happen. If the check valve is stuck and more fluid is going to the rear than supposed to, the brakes aren't going to work right. Just my 2 cents.
Posting Guru
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Make sure your vacuum canister doesn't leak.. it holds vacuum for a bit when the vehicle is off and helps braking with the power off. Because my brakes suck, without the canister attached my brakes almost don't work with the vehicle off. (both feet to the floor to keep it stopped at idle)
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The F350 Master cylinder brake lines come out the opposite site of the F150/250 MC's
Fender side...not engine side.
Fender side...not engine side.
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Fleet Mechanic
Joined: Aug 2007
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From: Piney Woods of East Texas
If the booster does not hold vacuum, check to see if the check valve is working. Generally it holds for 1 petal with the engine is off.
Even without the brake booster you should have brakes, as other mentioned, and not go to the floor. You may have to stand on them to get it to stop. The brake travel should be the same as with the power booster.
Even without the brake booster you should have brakes, as other mentioned, and not go to the floor. You may have to stand on them to get it to stop. The brake travel should be the same as with the power booster.
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The P.O. put new brakes all the way around, pads, shoes, drums, rotors. The brakes were a little soft when I brought it home so I bled them and they grab better now. I didnt see any leaks and the master cylinder is holding fluid. I gotta check the booster and for vacuum leaks and to see if I got the right master cylinder I guess would be my next move. Thats going to have to wait, it's Sunday and them Steelers are playing. Are you ready for some football?
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I would check the brake adjustment on the rear brakes for starters. If the booster has a vacuum leak, that can also have an effect on how the engine runs. Are the front brakes disc or drum? If drum, maybe they need adjusting. If disc, maybe teh pistons are stuck in the calipers, or there may be too much freeplay in the wheel bearings, causing the pads to be further away from the rotor than they are supposed to be.
Do the brakes pump up? having a manual trans as opposed to an auto tranny has no effect on the operation of the brakes. It is possible that the M/C is defective.
Good luck and let us know what you find out.
Drive safely,
Dan Harriman 84 F150 lwb
Orange, Texas
Do the brakes pump up? having a manual trans as opposed to an auto tranny has no effect on the operation of the brakes. It is possible that the M/C is defective.
Good luck and let us know what you find out.
Drive safely,
Dan Harriman 84 F150 lwb
Orange, Texas
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I don't know if we lost track or not but the brakes work fine as long as the truck is running. Driving along coming to a stop is no problem. Doing 45 on a empty road jamming on the brakes you come to a complete stop. Park it on a slight grade and take it out gear and she's rollin until you hit something or someone throws a 6x6 under the wheel. Pedal goes to the floor like its not even attached to anything. I'm pretty sure it is the wrong MC because like Mill1on said the lines connect on the engine side just like my F150. I'm in the middle of swapping cabs on my F150 this week of vacation of mine so if I get some time I'll take a run to my brothers since I have no room for it at my place. Any other suggestion are more than welcome and THANKS for the info so far.
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Not trying to beat a dead horse here or anything, but what I'm getting is if you stall out or lose power for any other reason, you're crashing? I better get that E-brake cable hooked up ASAP. Thanks to one and all.
P.S. The cab swap is going good so far. Got the donor off. A little body work here and there and primed. Half way on the 4x4 cab removal.
P.S. The cab swap is going good so far. Got the donor off. A little body work here and there and primed. Half way on the 4x4 cab removal.
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