Brake bleeding with cheap HF Vacuum Pump?

[timtaylor]

Has anyone ever thought to make a brake bleeding kit using this: http://www.harborfreight.com/air-vacuum-pump-with-r134a-and-r12-connectors-96677.html

anyone see any problems with using that to vacuum the old fluid out of the lines?

 

[ATTappman]

For about $25 they sell a vacuum brake bleeder kit that works acceptably well, if you can get the rubber adapter to seal around the bleeder screw. Why build your own? Either way, you need a source of compressed air, so you might as well pay the extra $10 and get something designed (as well as anything HF sells is designed) for the specific job?

 

[timtaylor]

For about $25 they sell a vacuum brake bleeder kit that works acceptably well, if you can get the rubber adapter to seal around the bleeder screw. Why build your own? Either way, you need a source of compressed air, so you might as well pay the extra $10 and get something designed (as well as anything HF sells is designed) for the specific job?

i have a compressor. i saw the hand vac ones and have read the reviews. it seems a bit spotty.

 

[gt40mkii]

I NEVER bleed using vacuum.

Putting a vacuum on the brake fluid reverses the pressure differential across all the seals in the system (caliper/cylinder seals, and master cylinder seals, plus whatever's in the ABS pump.) These seals may not be designed for this and air can get pulled past these seals (its happened to me on more than one occasion.)

If you simply MUST use something than the traditional two-man approach (which I still use, even at the track,) get/make a pressure bleeder.

 

[chrisexv6]

Ive used a MityVac to bleed and it seems to work just fine. As far as pulling seals thru because of the vacuum, I dunno....I didnt really crank down on the vac pump, just enough to get the fluid to start flowing. One of the MityVac kits comes with a small container that the fluid will run into.....the small one is probably fine for bleeding a little air out of the caliper, etc during a pad change but for a full flush youd need something bigger.

But the easiest way is something like the Motive PowerBleeder. Its so easy I actually do complete fluid changes anytime I change a set of pads.

 

[timtaylor]

I NEVER bleed using vacuum.

Putting a vacuum on the brake fluid reverses the pressure differential across all the seals in the system (caliper/cylinder seals, and master cylinder seals, plus whatever's in the ABS pump.) These seals may not be designed for this and air can get pulled past these seals (its happened to me on more than one occasion.)

If you simply MUST use something than the traditional two-man approach (which I still use, even at the track,) get/make a pressure bleeder.

I'm not too sure about the seals. I'd imagine there would be no different if you're pushing the fluid (2 man bleed) vs vacuum (1 person bleed) because it's not like we're talking about crazy suction.

Ive used a MityVac to bleed and it seems to work just fine. As far as pulling seals thru because of the vacuum, I dunno....I didnt really crank down on the vac pump, just enough to get the fluid to start flowing. One of the MityVac kits comes with a small container that the fluid will run into.....the small one is probably fine for bleeding a little air out of the caliper, etc during a pad change but for a full flush youd need something bigger.

But the easiest way is something like the Motive PowerBleeder. Its so easy I actually do complete fluid changes anytime I change a set of pads.

i looked up the motive powerbleeder. looks like a pressurized system that can be built easily: http://faculty.ccp.edu/faculty/dreed/campingart/jettatech/bleeder/index.htm

 

[gt40mkii]

Ive used a MityVac to bleed and it seems to work just fine. As far as pulling seals thru because of the vacuum, I dunno....I didnt really crank down on the vac pump, just enough to get the fluid to start flowing...

It's a crapshoot. I know folks who swear by vacuum bleeding -- they say they've never had an issue. I've been bitten by it before. several times on street cars and twice on a race car.

The last time was on a race car. We never could get a firm pedal after a brake swap. Everything brake related on the race car was new except for the hardlines (calipers, hoses, master cylinder, etc...) The owner filled up the master cylinder's remote reservoir with Castrol CRF and I started pumping at the farthest brake caliper, working my way to the closest with him monitoring the fluid level so that it never ran dry.

We had spongy brakes and a long pedal -- classic signs of air in the system. So we re-bled. We got bubbles and a spongy pedal. Bleed again. Bubbles and spongy. One more time -- bubbles and spongy.

By this time we'd run out of SRF (and at $75 per quart, this stuff is expensive!) so after buying more fluid, we switched to the two-man method. BINGO! We pumped out a ton of air and got a nice, firm pedal.

In all We pumped about 2 QUARTS of fluid through the system before we got all the air out. The system's capacity is about a quart, maybe a touch less.

As far as we can tell, the mightyvac was pulling air in at the master cylinder and pulled it through the entire system. Thank God the car didn't have ABS -- I don't relish the thought of bleeding an ABS system with air in it.

 

[lametec]

This type hasn't failed me yet:

$4 at Harbor Freight.

 

[gt40mkii]

I'm not too sure about the seals. I'd imagine there would be no different if you're pushing the fluid (2 man bleed) vs vacuum (1 person bleed) because it's not like we're talking about crazy suction.

Depends entirely on the design of the seal and the part. Lots of master cylinders use cup seals on the piston. These act as one-way valves. when pushing the pedal, they seal and build pressure in the system. On retraction, they allow fluid from the reservoir past to keep the pedal high and firm (if they didn't, as pads wore, the pedal would become lower and lower as the caliper pistons moved farther anf farther out.)

If air gets into the un-pressurized part of the master cylinder, the one-way seal will **** it onto the pressurized part of the system. Air can get by the seals at the master cylinder's reservoir or where the brake rod attaches. These seals are not designed to seal a vacuum and can sometimes leak (it's not common, but it happens.) Our leak appeared to be where the reservoir tubing met the master cylinder. Fluid wouldn't leak out, but air could get in, apparently.

Also, air can get pulled in past the threads of the bleeder screws themselves. This doesn't introduce much, if any, air into the actual braking system, but it can give you a false indication that there is still air in the brakes. If you are going to vacuum bleed, put some kind of sealant on the bleeder screw threads to keep this from happening.

 

[timtaylor]

I NEVER bleed using vacuum.

Putting a vacuum on the brake fluid reverses the pressure differential across all the seals in the system (caliper/cylinder seals, and master cylinder seals, plus whatever's in the ABS pump.) These seals may not be designed for this and air can get pulled past these seals (its happened to me on more than one occasion.)

If you simply MUST use something than the traditional two-man approach (which I still use, even at the track,) get/make a pressure bleeder.

This type hasn't failed me yet:

$4 at Harbor Freight.

my spoon is tooooo big!

 

[gt40mkii]

Mine:

There's no internal hose to the bottom of the container though, so it's strictly for a two-man procedure, or pressure bleeding.

 

[timtaylor]

Mine:

There's no internal hose to the bottom of the container though, so it's strictly for a two-man procedure, or pressure bleeding.

not bad. mine's pretty rudimentary. i have a clear tube plumbing in to an old brake fluid container. i tilted my container over last time and some fluid spilled out

 

[gt40mkii]

not bad. mine's pretty rudimentary. i have a clear tube plumbing in to an old brake fluid container. i tilted my container over last time and some fluid spilled out

What you can't see easily is that the neck of the container has a 8" steel wire permanently attached to it. On the other end of the steel wire is a loop used to hang the bottle from whatever is convenient (usually a wheel stud,) freeing up your hands to work the bleeder screw easily. Also makes it harder to knock the bottle over when its hanging. The bottle is also capped with a *tiny* air escape hole, so even if you do manage to knock it over , not much comes out of the cap. Some does come out of the tubing though.

These things are tough. I've used mine for well over 10 years now.

 

[timtaylor]

i'm still contemplating the idea of a vacuum pump though. i mean, a slow steady pump (like with a bike pump but a vacuum -duh) to remove the fluid sounds like a good idea..
http://www.practicalmachinist.com/vb/general/ot-home-made-break-bleeding-setup-208620/

 

[earlthegoat2]

Vacuums, I have found, to be a waste of time and money.

Just get a friend and crack the bleeder while your friend pushes the brake pedal. Ages old and still works best.

 

[tonycastec]

If you plan to keep the car a while I recommend "Speed Bleeders". You need some 'clue' when installing them but after that they are flawless and simple.
They have their own website and are really helpful people. On EBay too.

 

[VC455]

I got the one with the Brass Body it worked a couple of times and then the plunger pulled loose from the bellows so the rod that the handle actually activates was just dangling loose,
junk

 

[Tonyuk]

We vacuum bleed all the time at the dealership, with the pressure and inlet being connected to the master cylinder reservoir.

Works every time, we dont even take the wheels off alot of the time. Don't forget the clutch slave if its hydraulic.

 

[redvalkyrie]

Motive Power Bleeder. Has never let me down. A little more money but man is it worth it.

 

[5ktq]

I've never had much luck with vacuum, I'd pull a couple ounces and have a sore hand from pumping the thing. Maybe OK for clutch, but for brakes I'd vote against.

 

[gte718p]

I NEVER bleed using vacuum.

Putting a vacuum on the brake fluid reverses the pressure differential across all the seals in the system (caliper/cylinder seals, and master cylinder seals, plus whatever's in the ABS pump.) These seals may not be designed for this and air can get pulled past these seals (its happened to me on more than one occasion.)

If you simply MUST use something than the traditional two-man approach (which I still use, even at the track,) get/make a pressure bleeder.

We vacuum bleed all the time at the dealership, with the pressure and inlet being connected to the master cylinder reservoir.

Works every time, we dont even take the wheels off alot of the time. Don't forget the clutch slave if its hydraulic.

Don't know about other brands, but Porsche service manual specifically calls for vacuum bleeding.

Of course I'm sure is a bad idea, the engineers who wrote the manual know nothing about how the system is designed, and you should never vacuum bleed brakes

 

[theoldwizard1]

Old school. Gravity bleed into a bottle. 2 man bleed to finish.

 

[techieman33]

I'm a fan of speed bleeders. You can also get a little check valve that will attach to a normal bleeder if your working on multiple vehicles.

 

[frank001]

I have a MityVac vacuum bleeder that I have had for decades. Still works fine and has never failed me on many different vehicles.

 

[6PTsocket]

I have the Motive. At one point I figured out which garden hose sprayer they had modified. The gauge is located where the garden hose sprayer had it's bleed valve. The thing that makes the Motive good and can add up in cost are the master cylinder adapters. They are well made and far better than some general purpose plate that is held with a chain or some other crude arrangement. It comes with the adapter of your choice to get you started. In the end you don't save that much modifying a garden hose sprayer. I prefer pressure bleeding because you don't have to worry about leaks at the fittings, need a separate compressor, running out of brake fluid or need any help.

I'm not too sure about the seals. I'd imagine there would be no different if you're pushing the fluid (2 man bleed) vs vacuum (1 person bleed) because it's not like we're talking about crazy suction.


i looked up the motive powerbleeder. looks like a pressurized system that can be built easily: http://faculty.ccp.edu/faculty/dreed/campingart/jettatech/bleeder/index.htm

Sent from my SM-G900V using Tapatalk

 

[Tonyuk]

Don't know about other brands, but Porsche service manual specifically calls for vacuum bleeding.

Of course I'm sure is a bad idea, the engineers who wrote the manual know nothing about how the system is designed, and you should never vacuum bleed brakes

VAG specifically calls for pressure bleeding in all of their vehicles. They have done since i started working there years ago.

 

[kelpaso1]

I find on a lot of ATV's and motorcycles I can not get fluid to come out of the bleeder by pumping the MC if the system is dry (ran out of fluid). I have to use the vacuum bleeder to get the fluid to mostly fill the lines and calipers first. Then I can manually pressure bleed to get the rest of the air out.