[64speed]

Not my first rodeo but dont want to spend time chasing my tail either. I switched to hydroboost over a brake booster. Now the engine is not in the car so I cant run it but I am trying to bleed the new system because I need to be able to stop it when I roll it off the trailer etc, plus I live on a hill so....anyway, the new system bolted up and got the pedal hooked up. I filled the master up and hit the pedal and left it on the floor for a second like I always have. It took a little bit from each bowl and then no more so I started pumping it and it took no more. I am going to have a helper for a little while tomorrow so I am gonna finish it out hopefully but I dont want to spend time chasing my tail. Should it have taken more than just a little? Am I gonna have problem bleeding it out the rest of the way or is it just air in the lines? I dont want to waste the time I have with help. Anybody got any tips or tricks?

[CraigG.]

One of the easiest and completely effective ways of bleeding brakes - only way I got all the air out - been trying for 20 + years.
https://www.summitracing.com/parts/mvp-0105?rrec=true

[geeteeohguy]

Always bench bleed a master cylinder before installing it. I have used a syringe and injected brake fluid into the master through the outlet ports until the air bubbles stop and you get a stream. Works 100% of the time, have used it for 30+ years when in the industry. You fill the MC reservoir up about 1/3 of the way, and do one port at a time. It takes about 3 minutes total. If that. Bolt it on the car, leave the cap loose so air can displace the fluid, and gravity bleed the brakes starting with the pass side rear, going clockwise. Keep an eye on the reservoir and add fluid as needed. No need to pump the pedal, no need for help. Takes about 15 minutes to an hour once you get solid dripping, close the bleeder and go to the next. Easy peasy.

[Formulabruce]

One key to doing this without a pump or vacuum source is to go very very slow. Also,, you might be able to do a "bench bleed" on the car if careful. From experience I can tell you when the engine stalls on a hydroboost system the brakes are extremely poor. Worse than and other power system. Good luck!

[mgarblik]

Originally Posted by CraigG.

One of the easiest and completely effective ways of bleeding brakes - only way I got all the air out - been trying for 20 + years.
https://www.summitracing.com/parts/mvp-0105?rrec=true

That's a cute little kit, but make sure you have several bath towels under the master cylinder to catch the leaks when you pressurize the MC cover. That's always the issue with any pressure bleeder, keeping the fluid from leaking out all over your restored engine compartment. As most know, brake fluid removes paint instantly on contact. You can save the $67.50 by simply gravity bleeding at the 4 wheels after bench bleeding the master cylinder. That helps isolate the possible leaks outside the engine compartment. Pressure bleeding is really nice for newer cars with anit-lock systems. It saves time by forcing fluid through the tiny passages in the anti-lock valve blocks. Gravity bleeding will work but takes much longer.

[SRR]

Originally Posted by Formulabruce

One key to doing this without a pump or vacuum source is to go very very slow. Also,, you might be able to do a "bench bleed" on the car if careful. From experience I can tell you when the engine stalls on a hydroboost system the brakes are extremely poor. Worse than and other power system. Good luck!

I almost put my wrecker into the neighbors fence when it stalled.

[TedRamAirII]

Originally Posted by SRR

I almost put my wrecker into the neighbors fence when it stalled.

That's odd...if the pressure accumulator was working, you should have 2-3 boosted pumps left?

[Tom Vaught]

Originally Posted by TedRamAirII

That's odd...if the pressure accumulator was working, you should have 2-3 boosted pumps left?

Agree. Ford has had Hydroboost on its Mustangs since 1996 and they would never have offered the system on a performance vehicle if the brakes did not work properly on an engine stall. I drove a 760 hp 4.6L Vortech Supercharged 4.6L Mustang test vehicle for several years and never had one issue with the Hydroboost brakes.

The hydroboost was required because of the boosted engine. No Vacuum to work the brakes when under boost.

Tom V.

[CraigG.]

You guys have good ideas. I just had good luck with mine - the trick is to clamp it down with one big c- clamp - if the master is all metal.

[Sirrotica]

Originally Posted by TedRamAirII

That's odd...if the pressure accumulator was working, you should have 2-3 boosted pumps left?

Exactly, I have 2 diesel chevy trucks, and an International diesel wrecker with hydroboost on them, they all have at least 2 applications without the engine running. If your losing brake boost the minute the pump quits running your accumulator system is malfunctioning.

There is also an electric powered over hydraulic pump used as an emergency pump on some school buses I used to own, that will run to apply the brakes if the engine is shut off, and you need brake application with a hydroboost system. The manufacturers have covered themselves with emergency alternatives in any applications I have seen.

There are a lot of construction equipment that is diesel powered that I have worked on, that also use hydroboost for brake functions, they all have accumulator systems in case of emergency. Hydroboost stands out in applications that the engine has little, or no vacuum signal to assist in applying brakes. It also can be adjusted for more line pressure where needed such as heavy equipment applications, it's very versatile.

[indymanjoe]

No motor in car no reserve pressure..

[mgarblik]

Originally Posted by TedRamAirII

That's odd...if the pressure accumulator was working, you should have 2-3 boosted pumps left?

Absolutely true. First stop should feel the same as if the car was running, second, may be a little stiff. Third, push HARD!

[Cliff R]

When I went to school decades ago they taught us that gravity and time was the best and most effective method to bleed brakes. However time is not always an option.

I use a mighty vac pump to speed thing up some, but have also used the pressurizing the master cylinder method and it works excellent provided you get a good seal and don't leak out fluid as mentioned.......

[mgarblik]

Originally Posted by Cliff R

When I went to school decades ago they taught us that gravity and time was the best and most effective method to bleed brakes. However time is not always an option.

I use a mighty vac pump to speed thing up some, but have also used the pressurizing the master cylinder method and it works excellent provided you get a good seal and don't leak out fluid as mentioned.......

That's an excellent point. I often use the combination of gravity and vacuum bleeding to speed things up. Get the bulk of the air out with vacuum and establish the fluid flow, then finish with gravity. One man operation, start to finish usually around 1/2 hour.

[Old Goat 67]

Have done pressure bleeding for 30 plus years. Never do it any other way.

Just recently complete system overhaul on my Tahoe. Changed over to DOT5, so cleaned all lines with denatured alcohol, new master, rebuilt all calipers.

No bench bleeding necessary, pressure bled all four wheels, done in 15 minutes. Pedal rock hard. No wasted fluid, no mess.

[Formulas]

I have a flat plate with sheet silicone on it that I connect a vacuum source and put on top of the master and it sucks air out of anywhere in the system

A day or so later I bleed at the wheels for a warm fuzzy

I do however have to watch how much vacuum I put to it as its possible to draw air past the cup seals on drum brakes and that serves to airiate the fluid

[Schurkey]

I gravity-bleed for minor work at the wheel cylinders or brake hoses. Gravity bleeding has almost no set-up or take-down time. No equipment to locate in the shop beyond a wrench for the bleeder screw(s) and whatever it takes to pop the master cylinder cover off.

I pressure bleed for major work, or work at the master cylinder. I have to dig the bleeder out, make sure the adapters are clean, connect everything...and then reverse that procedure to put it all away. But the bleeding itself goes really quick. I just hate seeing people wasting money on "garden sprayer" "pressure bleeders" like the Motive. Proper pressure bleeders have a rubber diaphragm to separate the fluid from the air used to pressurize the bleeder. That way, humidity in the air can't contaminate the fluid before you even put it in the master cylinder. A proper pressure bleeder also has quality master cylinder adapters that don't leak all over creation. And don't get me started on folks using clamp-on style adapters on plastic master cylinder reservoirs. The plastic isn't designed to be compressed by the reservoir adapter.

Pulling a vacuum on the system at either end (wheel cylinder or master cylinder) is not something I recommend. Vacuum bleeding--especially at the wheel cylinders--is popular, though. As said, drum brakes have a tendency to pull air past the wheel cylinders, and you'll have to seal the bleeder screws for the same reason. Vacuuming the master cylinder--just like "Reverse Injection" bleeding, can pull the most-contaminated fluid (usually the stuff in the wheel cylinders) through the ABS or proportioning/metering valves, which doesn't do them any good. Ideally, you'd flush the system before allowing fluid to travel backwards through the system--and by the time you've flushed it in the normal direction, you're essentially done. At that point, reverse bleeding is redundant. And reverse bleeding MUST be followed by a quick bleed in the regular direction, because the wheel cylinder fluid connection is always lower than the bleeder screw--so the distance between the fluid connection and the bleeder tends to hold air.

I never seem to have a helper to pump the pedal. Which is fine, because I get more done by myself than when I need to entertain my "helpers". Or supply them with libation, which quickly destroys momentum and ambition.

[Sirrotica]

Agree with Shurkey, especially the pressure bleeding with no diaphragm between the moisture laden compressed air from a compressor. Moisture is forced into a hygroscopic fluid under pressure. That's a sure recipe for extra unwanted H2O in the already vulnerable brake fluid, even worse than leaving brake fluid unsealed to the atmosphere, and then pouring it into the brake system. However some people think it's perfectly acceptable.

It's not like bleeding pipelines in a refinery, because oil doesn't attract water from the air, like brake fluid does.

Speaking from experience, anyone that has worked as a flat rate mechanic, making their living on how expediently they can produce a finished, acceptable quality job, uses gravity to bleed brake systems. There are a few exceptions that it isn't the fastest, such as what Mike G has expressed, but 95% of the time you'll finish faster, with less hassle using gravity. A siphon is governed by the laws of nature, and works 100% of the time.

[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?

[Lemans64]

Not sure if gravity bleed will work if you don't bench bleed the master cylinder. If you did, just crack the bleeders loose and wait for fluid to flow.
Once fluid is flowing out the bleeder, tighten it and go to next one. Once you have done all 4 corners, step on the pedal a few time then crack the bleeder again, foot off pedal.
You will probably get a few air bubbles out. repeat till clear.