Can you bleed brakes on a slope?
 

The brakes in my 77 F250 4x4 have deteriorated. The pedal goes almost all the way to the floor with no resistance. The truck will stop, but it's a bit unnerving.

I've never worked on brakes before, but it seemed like a classic case of a bad master cylinder. I ordered a replacement and picked up one of those vacuum pump kits. Bench bleeding the master cylinder and replacing it seems very straight forward. I'm not so sure about bleeding the brake system though!

My driveway is a bit of a slope. It's not very steep, but it's definitely not flat. Can I succeed with this if the truck is not flat? If it will work on a slope, would pointing the truck one way or the other be better?

I would not think a gentle slope would hurt... though it would be a bit harder to get air out of the downhill side.

If you plan to jack it up and it is safe to do so, you can just set one end lower and level it.

Or... I always prefer to bleed the brakes once, let it settle so any little air bubbles can combine and do it again. You could do it the first time facing one way and second time facing the other. After the first bleed, you should have decent pedal... the second time is to make it as good as possible.

I would suggest you get a cheap Chilton or Hanes manual and get to reading on your brake system, like how to bleed them. Then I would suggest you join you FTE state chapter and get some experienced help with your brakes. They are not a learn as you go system..

Brakes either work absolutely as they should and when they don't, you should stop (if you can lol) driving the vehicle and get them fixed. PERIOD!

Washington Chapter - Ford Truck Enthusiasts Forums

Bench bleed m/s is easy, self bleeding and getting it right not so much. Having a pedal pusher (and hold) sure makes it go faster and better.

Oh and since you are pushing fluid during the bleed process, being on a slope does not matter, it only matters to keep the fluid in the m/s full all the time.

My quicky thoughts are that because it is a closed system, you could bleed the brakes with the truck standing on its nose .... or roof. The only drawback in that theory would be the master cylinder of course. (and yeah,I know,sometimes under ideal conditions ya' can't get the darn air out). Just sayin'. gary

I my opinion yes being on a slope makes a big difference, my 79 was on a slope after i redid the brake lines , i bleed the brakes for hours over a few days and was at a complete loss. i thought maybe that was why and i jacked up the back so it was higher than the front and the brakes bleed in minutes.

that`s my experience so i would say yes. air bubbles rise !

The air needs to get out through the bleeders. If the slope prevents that then some will be trapped.

If you are gravity bleeding the system, then yes a slope matters. If you are bleeding the system by pumping the master and holding while someone lets the air out, then it shouldn't matter at all.

A vacuum system works OK either way as well, but I find that it takes a little finesse to get a vacuum bleed to work right. Loosen the bleeder/nipple too much and it seems like you can pull vacuum from around the threads, reducing the effectiveness of the vacuum. Don't open it enough, and it doesn't work either. Having a helper pump the brakes is the best in my opinion and what I prefer if someone is around, but I've been able to get a decent bleed with a vacuum as well (air powered venturi bleeder system, not the little "Mighty Vac").

If you purchase one of these, you can bleed the system all by yourself (no buddy). They work great. I personally wouldn't worry about being on a slope...

Air bubbles rise if the master cylinder is higher than the back the air stays at the top. Maybe it's not impossible but makes it a lot harder to bleed . From the front to the back is a long run. May as well give yourself the best advantage as you can.

Good discussion! Thanks for the pointers and encouragement. I do have something like the mityvac but I'm still hoping to get a friend over to lend a hand.

I will point the nose downhill just in case.

Thanks again, I'll post my results in a few days.

Let use know how you make out!

Well, finally some good weather and a little free time. I managed to get the new master cylinder bench bled. LMC sent me a Cardone replacement MC. Things went just as described in the instructions.

Onto removal of the old MC. I wire brushed around the brake tubes and sprayed a little PB Blaster on them. The threads broke free but the tubes were completely frozen in the fittings and started to twist :( I tried to wiggle back and forth on the fitting, but it was just too seized up... I figured I was screwed either way so I tried to tighten them back up and the front tube broke. At this point I decided I could at least get the new MC installed, so snap went the 2nd brake pipe.

I'm starting to think every fastener in this old truck is frozen solid. Getting the old MC off the booster took PB, a breaker bar, flame, swearing and an impact gun. Both nuts will have to be replaced.

It looks like I'm now in the same boat as this guy https://www.ford-trucks.com/forums/1...e-options.html

My question is should I replace the brake booster now that everything is torn apart and until I can get new brake lines, the truck isn't going anywhere... The booster itself is rusted quite a bit and splined rod that comes out of the booster is pretty rusted on the end that goes into the MC. The part of the rod that was inside the booster is clean and shiny.


https://cimg0.ibsrv.net/gimg/www.for...e3765a81b2.jpg

And for the curious, this is what the old MC looks like

https://cimg5.ibsrv.net/gimg/www.for...36fde27599.jpg

May be one reason a lot of trucks got parked on the back 40, back in the day. It's almost impossible to replace just some or part of the brake system, the original parts are more prone to failure because of the restored hydraulic pressure e.g. a new master cylinder may blow out old hose or new shoes mean the wheel cylinder cups may start to leak. And then there's the original hard steel line. You can see where this is going, right?

On the booster, I did not change mine with new MC but kinda wish I did... even though it works fine. The working part inside the booster is rubber. I have to believe time takes a toll.

It is not too hard to repair the brake line and get her rolling. That said, nice pre-bent replacement line sets are not too expensive from the vendor of your choice. I like in-line tube. If you do the lines, best to go ahead and do the flex lines since they are likely frozen also.

Also a tip... if the brake line is frozen hard to the nut or will be scrapped anyhow, just nip it off with bolt cutters. Saves time and you can use a socket on the tube nut.

My experience...

I replaced front pads on trashed rotors to try to get by for a few months, bled the brakes while I was at it. Mushy pedal, not a lot of stopping power.

Replaced master cylinder (no booster on mine), bled brakes again. Good for a couple days and mushy again...

At that point I shelled out for all new parts: front rotors, bearings, calipers, and pads again. In the rear new shoes, spring kits, wheel cylinders, and drums. Also new hard lines on the rear axle and all new flex hoses.

Bled brakes, adjusted shoes, bedded in the pads/shoes, adjusted shoes again. SOLID pedal and awesome braking power.

Don't waste time chasing your tail, 40 year old braking systems should be gone through 100% front to rear.