at my wit's end with brake bleeding (who else says "blake breeding" on accident?... ok just me ) anyways...

tried the old fashioned "get a buddy" method... this helped me find all my leaks... fun.. so after replacing all the lines, the master cylinder and a rear caliper, we tried again (3 weekends into this so far... ) Builds a little pressure, go to next wheel.. try again.. no change, but good flow..

after doing all 4 corners and getting good flow with no air at each one, STILL pedal almost goes all the way to the floor with little pressure...

finally got to that point where you don't mind spending money to make the process easier, so i went to FLAPS and got the MityVac thing... $40 later i get home and go back to work... got the process down and got good flow at each tire again, reservoir staying full throughout... STILL sh*tty pedal feel... so at the time of this writing.. i quit!

Hows the venting clearance of the rear brakes? If too big, most of the pedal is used bringing the pads closer to the rotors.

Is it a soft pedal or does it goes down a long way then you get pressure?

Can you pump it up and get a good pedal?

You can try the gravity method by opening one caliper at a time and let gravity bring out the fluid.

My buddy tracks his 911 and between weekends he flushes the brake system by using a different color fluid like yellow with the gravity method. Let each one stay open until the normally blue fluid turns yellow, then go to the next one.

I too tried the MityVac, and it just doesn't work that well. Pulls air from the threads on the bleeders. Pressure on top of the brake fluid works every time for me, and makes it a one man job.

Here's how I bleed a 914 brake system, from my post back in Mar 05.

Remember the "Search" function is your friend!

Get a spare cap for the brake fluid resevior.
Get a tire valve & stem.
Drill a hole in the center of the resevior cap, the same size as the hole in a wheel (or measure the narrow part of the tire valve).
Pull the valve stem through the hole.
Remove the plastic screen in the resevior.
Fill the brake resevior completely, not to the fill line, all the way full to the bottom of the tube that holds the plastic screen.
Put on your new modified pressure bleeder cap.
Drain your air tank to 10 psi, for cheaper compressors setting the regulator at 10 psi may not work. If you put too much pressure in the system, you'll blow off the blue lines that connect the supply lines to the resevior, or worse.
Take a clip on air chuck and clip it on your new pressure bleeder cap.
Bleed the brakes, starting at the furthest bleeder from the master cyl, and finish at the bleeder nearest the master cyl.
Bleeding sequence (RR-LR-RF-LF) EDITED FROM ORIGINAL POST
Pump the pedal hard about ten times and repeat the proceedure.
Do not get brake fluid on painted surfaces it will ruin them.
If the pressure bleeder cap retains pressure, bleed it down before taking it off the resevior.
This works very well, and makes it a one person job.
Replace brake fluid every two years.
Properly discard used brake fluid.

If you have speed bleeders, try the long tube method. put tubes that go from the bleeder screw all the way back to the brake fluid tank. Crack them, and just start pumping. You can do all four at once, or do them one at a time. Works w/o speed bleeders too, but is slower. Its nice because you don't have to keep filling the fluid tank, and since the tubing is clear you can see when you are no longer pumping bubbles. remember to knock around the master cylinder and prop valve on the firewall - air hides in these. I used this method to get rock hard brakes.

If you don't have speed bleeders, get one of those Motive pressure bleeders. They DO NOT work with cars that use speed bleeder valves, but work miracles for cars that use standard valves. I actually removed my speed bleeders so that the Motive would work - thats how much nicer it is. Those vaccum bleeders are garbage.

Zach

must add a me too to the vacuum not working. Just like Perry said - draws air along the bleeder threads so you think there is still air in the system.

The long tube method saved my marriage, no joke. I don't bleed the brakes any other way.

BTW, it will work even without speed bleeders. Be sure to purchase a new length of tubing every time you do this. Otherwise, the residual fluid in the tube will collect water vapor out of the air and put it back into your brake system.

dammit, i thought the MityVac one was THE one, and now I'm remembering the Motive one... ugh...

the long tube method sounds cheaper than the motive, so I might try that. should I order speed bleeders?

i wonder if the FLAPS would take a return on this thing.

i haven't touched the proportioning valve or done anything but reinstall a new master cylinder (no bench bleed). do i need to do anything special with these two or just tap them like you said?

also, i have one rear caliper that has 2 valves, and one that has 1 valve (top). i did the bottoms on the ones with 2 and the single on the one with 1.

also, dumb question and I could probably search forum for it, but will the engine bar support the car if i put 2 jack stands under it? this one wheel at a time, removing and rinstalling is getting old

how about 2 stands under the steering rack in the front (the stationary part)

would this one work on the 914: http://www.autopartsdealer.com/motive_prod...-p246065-p.html

Your problem. I just found it.
Do air bubbles move up or down? Ignore the bottom valve and do the top valve. You will never get the air out of the system if you use the bottom valves.

Zach

oh, i was following the pelican article:

"If your rear caliper has two bleed nipples (some have one, others have two), bleed the lower one first."

i haven't even touched the top ones yet. do I need to do both on each caliper??

1. Bleed nipples are always on top. Air bubbles rise. A lower nipple is used to remove old fluid when you are pushing the pistons back into their bores during a pad replacement to keep from pushing fluid back to the MC. But there may be two bleeder nipples on the inside and outside, and at the TOP of the caliper. Bleed the inside first and then the outside. If your only bleed nipple(s) are at the bottom then the calipers are on upside down... i.e. on the wrong side of the car.

Note: There is a school of thought that works, but is a bad idea and that's to pressure-bleed backward from the caliper to the MC. It would be fine on a completely new system. But crud and bad fluid would be sent back into the MC this way. A lower bleeder would work better in this method, but it's still a bad process.

2. Always bench-bleed the MC. That could well be be your problem all by itself. So much so that I'd remove it and do it even now.

3. Pressure bleeding is the bomb. Anything else is more work. Vacuum bleeding often doesn't move enough fluid at a rate fast enough to sweep the air out of nooks and crannies. The buddy method scrapes the MC cylinder bore far beyond it's normal range and possibly into corroded bore. Doesn't matter with a new MC but can kill rubber seals on an old one.



Good luck

think i'm gonna order the Motive, but not sure which one I need. A quick search showed a lot of different ones. anyone have a link?

Don't even touch the bottom bleeder valve. The air will rise.

Spend the money and get the Motive Power Bleeder.... well worth the money and you'll be able to bleed your brakes as often as you need to. Right tool for the job.

Don't know on the link that you posted, but George sells them through AA with the 914 cap included. Might be a buck or two more, but consider it supporting a vendor who supports the community.

AutoAtlanta - Motive Powerbleeder

Mike

ordered! got an email about a 10% discount the other day so it worked out!

Best price is at Racer Wholesale Parts.


http://www.racerpartswholesale.com/categor..._Brake_Bleeders

Call 'em for your car. They'll know the part number for your Porsche cap. I'm not near mine so I can't get the part number for you.

Note: If you get the universal kit with all of the adapters, you can do all of the cars and trucks you own. This is the only way to do an ABS system BTW. If the fluid level goes down to low on those systems you have to fiddle with the computer as well as the mechanical stuff.

This is what I did with mine. I use it on all of my cars, be they Jeep, Porsche, Toyota or Subaru.

Zach

adapters can be purchased separate as needed right? i got the kit from AA just now which has the proper one for the 914, which should get me started

I've done brakes several times with the mighty vac, works every time for me. I never use it for final bleed though, just to get the major bleeding done. Final bleed for me is usually the next day after all the little air bubbles settle out and use the glass jar trick.

Don't forget to bleed the proportioning valve. No bleeder here, you just have someone hold the pedal down while you crack the fittings open. Do the input side then the output. This made a HUGE difference in pedal feel.

venting clearance is imperative!!!!!!!!!!!!!!!!!!!!!!!!!

Here is my two cents .... Yes these are all good methods of dealing with brake bleeding. I have had really good luck bleeding all kinds of motorcycle braking systems with my "Vacula" It's made by the swiss. and man It has always kicked ass. Now i have not bled a 914 but will be tomorrow, when i reinstall my pedal assembly.

I'll let you know how the power bleeder (vacula) works

Question I have is about setting the brake pedal down with a wedge (2x4 to seat ). I read this How-to

http://www.pelicanparts.com/techarticles/9...leed_brakes.htm

didn't mention the step where you hold the pedal down (as if braking) and bleed the system in the usual way with the pedal down. What's the difference if you bled them with the pedal up?

All Brake GuRus, I have read all of the articles and there was not ONE mention of using a normal garage compressor with a MotiveProduct bleeder adapter.

https://www.motiveproducts.com/collections/...uropean-adapter

I can regulate at 15lbs, is there a -dumbass- thought I am missing on why everyone buys the pump bottle AND the adapter?

Many thanks in advance!
CTC911CTC

This right here!

I just crack the fittings at the mc instead of removing it from the car

No but there was an article on how to install a Schroeder valve in a reservoir cap so you could use the compressor. IIRC, the OP recommended setting the reg at 5psi.

I just did mine after 25 years of all being apart. Rebuild MC new brakes front and rear. Had my buddy do all the pumping, nothing was happening. Put a little compressed air into the brake reservoir with a tight rag sealing the edges, bingo we have peddle pressure, no leaks, all good.

I've had good luck in the past using a MightyVac to draw vacuum on the bleed screw and then having an assistant push the pedal to build pressure. Then rapidly open the bleed screw.

The combination of pressure in the system + vacuum on the bleeder results in more fluid velocity that will draw air along with it when the bleed screw is opened. As previously stated bleed from the top bleeder.

Tapping on the caliper with rubber mallet will also help move stubborn bubbles to the top.

Note: yes the MightyVac will pull bubbles past bleeder threads but these will not go backwards into the caliper - they are drawn to the vacuum source. Agree completely that with these bubbles flowing you cannot gauge the "success" of the bleed by whether there is air in fluid. In the end pedal feel is what determines success.

”wrong side of the car” Great Point! Pcar916

I have used the MityVac in the past with some success, but not much with our 914. Entire system was dry, I will try to pressurize the system from our shop compressor with 10psi.

DON'T ignore bleeding those lower valves! If not done for a long time, you will not believe how much crud and garbage comes out of them. Bleed the lowers first then the uppers. I use the Motive bleeder WITHOUT putting brake fluid in it; just use it to apply pressure to the system. I add fluid to the reservoir between each wheel. No mess to clean up afterwards.

Ansbacher

Adapting a larger container that could attach to the fluid reservoir might speed things up a bit. The in an out checking the level trying not to go dry is a pain. The level goes down fast when doing the rears. I think I have an extra cap (someplace) and will look for a fitting that fits the hose and put it in the cap.

I think it has been mentioned here before but I remove the bleeder screw and insert a tapered plastic fitting ( usually included with the vacuum device) that way the air sucking around the threads does not bubble.

Our 1975 project was missing a rear caliper, both front caliper's were loose and there wasn't a drop of brake fluid in the system. I had a Mityvac but have not used in several years. It appeared to be working, but didn't have enough vacuum. I installed a fitting to the brake fluid reservoir and pressurized the system to about 5 or 10 psi. Just had time to work on the rears today and the pedal is getting firm without doing the fronts. It is looking like the pressure method is working better than the vacuum system.

When vacuum bleeding, I put grease around the thread of the bleeder valve where it enters the caliper. Stops the bubbling. Clean when finished.
Andys