[RocktimusPryme]

Just a note on the Motive bleeder. I have one and its great. The one caveat to this is that the chain setup that comes with the GM dual master cylinder fitting it useless. It was the one common complaint in the summit reviews but I tried it anyway.

When that did nothing but make a mess I did what all the reviews said to do and secured it with a couple C clamps. After that it worked great. I would still expect a slight mess when you remove the fitting as it kinda overfills the master cylinder. But still a great purchase. Ignore the chains, use a couple c clamps and that thing is awesome.

If you have a MS that can take a screw on cap instead of the flat plate it works even better.



I have also used a trick where you attach a hose to the end of the bleeder and submerge that in bottle with brake fluid. This allows you to bleed them by yourself without a second person.

[mgarblik]

Originally Posted by RocktimusPryme

Just a note on the Motive bleeder. I have one and its great. The one caveat to this is that the chain setup that comes with the GM dual master cylinder fitting it useless. It was the one common complaint in the summit reviews but I tried it anyway.

When that did nothing but make a mess I did what all the reviews said to do and secured it with a couple C clamps. After that it worked great. I would still expect a slight mess when you remove the fitting as it kinda overfills the master cylinder. But still a great purchase. Ignore the chains, use a couple c clamps and that thing is awesome.

If you have a MS that can take a screw on cap instead of the flat plate it works even better.




I have also used a trick where you attach a hose to the end of the bleeder and submerge that in bottle with brake fluid. This allows you to bleed them by yourself without a second person.

That's been my exact experience over 40+ years of trying pressure bleeders. Success is 100% dependent on the fit of the cover on the MC. Muscle car MC's with a cover held on with a wire bail is the most likely to leak and ruin the engine compartment. Bad true story: When I worked at a Porsche dealer, we had a 911 in that needed bleeding. Beautiful metallic green car. Hooked the fancy pressure bleeder up, (Bear Brand) and set it up to work. We used these soft blanket, like fender covers. We were not allowed to use the typical vinyl style that are so popular. As soon as the valve was flipped, brake fluid began leaking at the cover of the MC. I immediately shut it off but it takes time for pressure to drop. The tiny fit issue at the cover seal let a stream of brake fluid shoot out over the sloping fender on the cloth fender cover along with getting fluid in the front fully flocked and finished trunk which was painted body color under the flocking. Well, you can guess the rest of this story. The owner was over the top ballistic when he heard what happened. My dealer had to strip the entire trunk area and replace. Send the car to the body shop and re-paint the trunk cavity and the front of the car from the windshield forward because the fluid had marred the fender through the cloth cover. Total fluid spilled, around 3-4 tablespoons but it ruins paint on contact. This was in 1980 and cost over $3000.00 in 1980 money. I had to pay the dealer $1000.00 insurance deductible or get fired. Lesson learned.

[Cardo]

Vacuum bleeding is how they are all bled on the assembly line. The difference from home is vacuum is drawn at the master cylinder cap on the entire system all at once. Vacuum is drawn and held for about 70 seconds for a leak check, and then pressure filled. Fully automatic except for hooking up the fill machine and installing the cap.

[geeteeohguy]

Originally Posted by 64speed

Ok so do I just compress the master cylinder, open the bleeders, and keep adding fluid till nothing but fluid comes out? Is that gravity bleeding? If so give me a physics lesson, how does it overcome the bends and rises in the lines?

Please re-read post number 3. I was a flat rate auto tech for years and years, did thousands of brake job, and have been ASE certified for 38 years....but what do I know? Many ways to get air out of a system, but the one I use is less fuss and muss and requires no compression, air pressure, power bleeders, vacuum bleeders, speed bleeders, or other nonsense. Just a cup of coffee and some patience.
Gravity overcomes the bends in the lines because of.....gravity. The master cylinder is higher than the wheel cyls and calipers, and their bleeder nipples are at the top of their bodies...so the fluid displaces the air and drives it out of the system all by itself. Neat, huh?

[Sirrotica]

Originally Posted by geeteeohguy

Please re-read post number 3. I was a flat rate auto tech for years and years, did thousands of brake job, and have been ASE certified for 38 years....but what do I know? Many ways to get air out of a system, but the one I use is less fuss and muss and requires no compression, air pressure, power bleeders, vacuum bleeders, speed bleeders, or other nonsense. Just a cup of coffee and some patience.
Gravity overcomes the bends in the lines because of.....gravity. The master cylinder is higher than the wheel cyls and calipers, and their bleeder nipples are at the top of their bodies...so the fluid displaces the air and drives it out of the system all by itself. Neat, huh?

It works just like a siphon does, I think I've already posted that though...................LOL

As long as the exit to the conduit is lower than the master cylinder reservoir, the fluid will run downhill. Halleluiah!!! it's a miracle.

Anyone that has earned their living working on cars, has probably tried all the whiz bang, latest, and greatest ways to bleed brakes, but after the dust settles, we old timers still use gravity. My father who was also a mechanic showed me gravity bleeding when I was 12-14 YO so it's been going on since they converted cars from mechanical brakes, to "juice" brakes, coming close to 80-85 years now. There's still gravity, and physics, it's really dependable, especially with only 1 person available.

[mgarblik]

Geeteeohguy, Sirrotica, and myself. Over 140 years of doing brake work between us. That's allot of brakes. We say gravity wins. Other methods may save time. Results will not be any better.

[64speed]

I wasnt trying to be obtuse. I just wondered how it climbed up the hill of the rubber hose over the axle.

[Sirrotica]

This is the best demonstration I could find:

https://www.youtube.com/watch?v=CZmP...=ScienceOnline

[Schurkey]

Originally Posted by Cardo

Vacuum bleeding is how they are all bled on the assembly line. The difference from home is vacuum is drawn at the master cylinder cap on the entire system all at once. Vacuum is drawn and held for about 70 seconds for a leak check, and then pressure filled. Fully automatic except for hooking up the fill machine and installing the cap.

Do I understand this correctly? They vacuum from the top (master cylinder) and then when the system is "empty", the fluid is filled from the top also?

That'd be great. The deeper the vacuum, the better it'd work. I'm surprised they can get drum brake wheel cylinders to hold vacuum, though.

If they vacuum from the top, and then fill from the bottom (wheel cylinders) that'd be great if the system were virgin-clean. In the field, with a previously-dirty system, I'd think that residual contaminated fluid would still get drawn backwards through the valves and ABS by the new fluid.

[Greg Reid]

Originally Posted by RocktimusPryme

I have also used a trick where you attach a hose to the end of the bleeder and submerge that in bottle with brake fluid. This allows you to bleed them by yourself without a second person.

That's the way I've done it for years. Bleed brakes by myself all the time...although I'm not sure at all why it works.

[Cardo]

Yep, you understand correctly. All vacuum and fill is done through the fill cap on the master cylinder. You are exactly right about a deep cycle vacuum. The assembly line moves fast enough and the cycle is long enough that in our case, there are 3 brake fill machines, and each one does every 3rd truck. It's about 90 -110 seconds to vacuum, hold and leak check, and fill. Actual fill time is probably 7-9 seconds. No drum brakes these trucks for the last 24 years.

[Schurkey]

Did they use that same procedure with vehicles that had drum brakes?

[geeteeohguy]

Originally Posted by Greg Reid

That's the way I've done it for years. Bleed brakes by myself all the time...although I'm not sure at all why it works.

Syphon effect is why it works.

[Cardo]

Schurkey, I honestly don't know. I think so, but the last time we ran something with drum brakes I was still in the back of the trim department shooting seat studs and putting in auxilary air conditioners.

[Greg Reid]

Originally Posted by geeteeohguy

Syphon effect is why it works.

I suppose that's right. And the submersion of the tube prevents sucking air on the release, only more fluid.
I've also used the one man bleeder that is a simple tube with a check valve in it. It always worked for me also...and for that matter, I've used gravity bleeding too. It worked but a little slow for me.

[RocktimusPryme]

The one thing I would add to the submersion method is I wouldnt use it on a car that had sat for a long time. If its spitting out rust and dirt you dont want that sucked back in.