tires and wheels Pressure bleeder

[hnichols]

Got a pressure bleeding kit from BavAuto. No instructions, which I guess means that using this thing is so obvious that only an idiot (like me) would have questions.

Anyway, after combing the archives, this is what I think is the correct procedure: fill the canister with brake fluid. Attach the hose to the cap that screws onto the reservoir. Pump the pressure bleeder (I assume that fresh brake fluid will run from the hose into the reservoir). Then release the bleeder screws, draining the fluid into a canister, through a tube submerged in fluid. Right to left, front to back. Then the clutch. Sound right?

Now my questions:

1. How much fluid should go into the canister?

2. What pressure to do you pump it to. 10-15 psi?

3. Should one disconnect the apparatus after bleeding each corner of the car, making sure there's no trapped air by pumping the brake pedal (in order to eliminate that brake if one should find air at the end)? Or should one bleed all brakes (and clutch) before disconnecting the pressure bleeder?

4. I assume the bleeder has to be pumped periodically throughout the operation. How frequently?

5. What size are the bleeder screws (I know I can check, but it would be nice to have all the tools ready before I pull the wheels). Will an ordinary open wrench do?

6. How do you depressurize the thing when you're done? I assume you don't just pop off the attachment connecting the bleeder to the reservoir.

I apologize if some of my questions sound stupid or obvious. Just want to eliminate as uncertainty as I can before I start. Thanks in advance!

Hugh

[02for2]

The Bavuato bleeder is a nice one. IMHO better than the Motive standard.

If you haven't flushed the system for some time, I would go 2 Qts. to flush all the crap out.

Into a container with the tube tip submerged in fluid.

Pressure no higher than 18 PSI.

Pump up as needed - don't let the pressure go too low.

IIRC, the bleeder valve is 7mm. Open end OK, but use closed end to initially break it loose. Proper tool is Flare Nut wrench (makes a great B'day gift!)

Start at Rht. rear and work your way forward to Lft. Front (farthest to closest to MC)

If you have a fluid reservoir that also serves the clutch, bleed the clutch too (same procedure). If not, all the contaminated fluid in the clutch lines will contaminate your new fluid.

IIRC, the Bavauto bleeder has a pressure relief button or screw on it. Be sure to clean the bleeder w/ denatured alcohol before storing it.

Cheers!

[JohnS]

Some folks (like me) don't like to fill the bleeder with fluid because it's a pain to clean up when you're done. Instead they just use it for the pressure (I stick to around 12 lbs.) and have to repeatedly depressurize and fill up the brake fluid resovour. There's a good FAQ on bleeding the brakes that you should read.

John

[steve k.]

Pull the old fluid from the reservoir if you are replacing the fluid. You should do that every 2 years. fill the reservoir to the MAX line with new fluid. To bleed the whole system you need about a quart/litter of fluid. Put that in the bleeder. Attach all things that you need. Do the bleeding. Then undo the top of bleeder to remove the pressure and undo the cap. All this will prevent fluid loss and you reservoir will be at MAX line when done. (i love physics

steve k.

[M3M3]

yes...read the faq write up. good instructions.

bleed screw size varies from 4.5mm to 9mm. they may have all been the same when the car left the factory, but after 40yrs you can count on several of them being different sizes after caliper rebuilds, replacements, breakage, etc.

does not matter which wheel you do first. they are all on different lines. the rear brakes are on the same line, but they are exactly the same distance from the MC as the fluid goes. old wives tale that you have to do the right rear first.

[hnichols]

Thanks everybody -- I think I'm ready to do this. Doesn't seem that difficult.

Steve, so you pull the old fluid from the reservoir with some kind of suction device before attaching the pressure bleeder? I was planning on pushing the old fluid our through the bleeders. But your suggestion makes sense, if I can find a way of removing the stuff from the top cleanly.

Hugh

[steve k.]

Thanks everybody -- I think I'm ready to do this. Doesn't seem that difficult.

Steve, so you pull the old fluid from the reservoir with some kind of suction device before attaching the pressure bleeder? I was planning on pushing the old fluid our through the bleeders. But your suggestion makes sense, if I can find a way of removing the stuff from the top cleanly.

Hugh

turkey baster works great

don;t forget to bleed the clutch too.

[JohnS]

Also,

If you haven't replaced the hoses from the fluid resevour to the master cylinder recently and also the grommets where the hoses connect to the master, make sure you check for leaks when you first presurrize the system. Good to try this first before filling pressure bleader with fluid (if you choose to fill it at all). If you see any leakage under pressure, you need to fix that first (ask me how I know). Also, under pressure, you might also see leakage at the grommet on top of the clutch master too (ask me how I know that too). Good luck,

John

[BillWilliams]

Also, remember brake fluid is a great paint remover.

Clean all spills with denatured alkehull

I find the nasty stuff to come from the clutch bleed

[jgerock]

I too have the BavAuto bleeder. Works great.

I pump the reservoir up with air (no fluid) and bleed each corner and the clutch cylinder.

[Kidasters]

Also, remember brake fluid is a great paint remover.

Clean all spills with denatured alkehull

I find the nasty stuff to come from the clutch bleed

Or large quantities of water. Brake fluid is hydrophilic - which means it loves water.

So - if you spill it on the paint, and you don't have any alcohol, lots of water will also work.

+1 to what everyone else has said about the pressure bleeder though. Very handy tool.

[M3M3]

Thanks everybody -- I think I'm ready to do this. Doesn't seem that difficult.

Steve, so you pull the old fluid from the reservoir with some kind of suction device before attaching the pressure bleeder? I was planning on pushing the old fluid our through the bleeders. But your suggestion makes sense, if I can find a way of removing the stuff from the top cleanly.

Hugh

turkey baster works great

don;t forget to bleed the clutch too.

yes, turkey baster is the tool for the job. get your own though...do not use the one from the kitchten. btdt..did not turn out well for me!

[02for2]

... Brake fluid is hydrophilic - which means it loves water.

Good advise!

But, FYI, the correct word is hygroscopic.

The main difference is that hydrophillic is mainly used to describe substances which mix well in or with water, while hygroscopic substances will actually pull moisture out of the air.

Similar, but distincly different.

Cheers!

[hnichols]

I don't know what I'm doing wrong: connected thew power bleeder to the reservoir, pumped it up to 12 psi, and no fluid released when I turned the bleed screws. Made no difference whether I had fluid in the canister or not. Then I did the brakes the old-fashioned way, with my wife pumping the pedal. No problems there.

Now the only thing remaining is the clutch. Gave another try with the pressure bleeder: no joy. Nothing comes out of the bleeder. Any ideas?

At this point I think I'll wait for my wife to come home and do the clutch the old-fashioned way too.

TIA.

Hugh

[steve k.]

you might have some crap in your lines. 12psi should be plenty to push the fluid through.

steve k.