Bleeding Brakes - Can't Get Any Pedal Pressure Options

[ThinAir]

Well, I've searched, but there are so many responses about bleeding brakes that it's almost impossible to sort through them... so I'll ask.

I replaced the front calipers on the '70 with a pair of those pretty ones from Eric. When I put the car up on stands for the job I had good brake pedal pressure. Now that the new calipers are installed and the lines reconnected I've bled the brakes. I blocked the reservoir vent. I use a Motive Power Bleeder.

I'm sure that I'm not getting any air out of the bleeders at the wheels, yet I have no resistance when I press the brake pedal - it just goes straight to the bottom.

It seems unlikely that the MC would go so suddenly, so I'm wondering what else it could be.

As always, this is work that is being done last minute to get my son's car ready for this weekend's Route 66 Ramble. Despite lots of trying, things never seem to get done well ahead of time!

[davesprinkle]

Well, I've searched, but there are so many responses about bleeding brakes that it's almost impossible to sort through them... so I'll ask.

I replaced the front calipers on the '70 with a pair of those pretty ones from Eric. When I put the car up on stands for the job I had good brake pedal pressure. Now that the new calipers are installed and the lines reconnected I've bled the brakes. I blocked the reservoir vent. I use a Motive Power Bleeder.

I'm sure that I'm not getting any air out of the bleeders at the wheels, yet I have no resistance when I press the brake pedal - it just goes straight to the bottom.

It seems unlikely that the MC would go so suddenly, so I'm wondering what else it could be.

As always, this is work that is being done last minute to get my son's car ready for this weekend's Route 66 Ramble. Despite lots of trying, things never seem to get done well ahead of time!

You've still got air in the master cylinder. I've used both the Motive Power Bleeder and the McMark Long Tube method. The Long Tube is better. The Motive Power Bleeder just doesn't move the fluid fast enough for good bleeding.

For either method to be effective, though, you've first got to get the air out of the MC. Start with a helper doing the pedal tango until you've got even a little action at the pedal. Then move to the Long Tube method and keep pumping fluid through the lines. It'll take a while.

[Heeltoe914]

(IMG:style_emoticons/default/agree.gif) : But also make sure you only go about 3/4 down on the pedal to prevent damage to the inside seals. Five pumps hold, open lines repeat several times on all fours.

Also before doing that you may have to crack the lines going into the pressure regulator pump and hold as well.

[type2man]

Yep, try not to push the pedal all the way down, because your original master cylinder(if it's been there for years) will have a groove where the seals are. When you bleed the brakes, you go past that point and if there is corrosion you will cut the seals up. It's difficult to bleed brakes without punching the pedal all the way down. if the pedal is spongy when you're done, time for a master too. Just did the brakes on mine(had a leaky rear aliper) and forgot to tell the guy pumping the brakes to go easy.....DOH!!! (IMG:style_emoticons/default/headbang.gif)

[Joe Bob]

Bleed, bleed, bleed....then sometimes you wait a day so that the bubbles settle out and do it again. I prefer the two man way....

[underthetire]

Believe it or not, you can actually open all the bleeders and let them gravity bleed. takes a while, but it does work.

[echocanyons]

Are the bleeders up?

[Dave_Darling]

Bleed the rear brakes first. You'd be amazed at how air pockets seem to teleport from one end of the braking system to the other...

--DD

[ThinAir]

You've still got air in the master cylinder. I've used both the Motive Power Bleeder and the McMark Long Tube method. The Long Tube is better. The Motive Power Bleeder just doesn't move the fluid fast enough for good bleeding.

For either method to be effective, though, you've first got to get the air out of the MC. Start with a helper doing the pedal tango until you've got even a little action at the pedal. Then move to the Long Tube method and keep pumping fluid through the lines. It'll take a while.

That's what I was thinking too. I'm not familiar with either of the methods you mentioned. I'll do a search for them, but if anyone can post a link to a thread describing them it would be appreciated.

I'm assuming that "pedal tango" means having my wife hold down the pedal while I bleed the rear calipers - or is there some fancy footwork way of getting air out of the MC?

[davesprinkle]

You've still got air in the master cylinder. I've used both the Motive Power Bleeder and the McMark Long Tube method. The Long Tube is better. The Motive Power Bleeder just doesn't move the fluid fast enough for good bleeding.

For either method to be effective, though, you've first got to get the air out of the MC. Start with a helper doing the pedal tango until you've got even a little action at the pedal. Then move to the Long Tube method and keep pumping fluid through the lines. It'll take a while.

That's what I was thinking too. I'm not familiar with either of the methods you mentioned. I'll do a search for them, but if anyone can post a link to a thread describing them it would be appreciated.

I'm assuming that "pedal tango" means having my wife hold down the pedal while I bleed the rear calipers - or is there some fancy footwork way of getting air out of the MC?

The Long Tube Method: Get about 15ft of clear 1/8"ID vinyl tubing from the hardware store. Insert one end into the open brake fluid reservoir. (I like to tape the tube onto the fender so it stays in place.) Put the other end of the tube on the bleeder nipple. Open the bleeder about 1/4 turn. Sit in the driver's seat and pump the brakes. Over and over. Until your leg gets tired. Then switch legs. You can watch the bubbles chasing themselves through the line. Do all 8 bleeders. This approach will leak a little fluid past the bleeder threads, but I've never had it pull air back into the caliper.

The pedal tango is just the std method of having a helper stand on the pedal while you work the bleeder: Pedal down, bleeder open, bleeder closed, pedal up, repeat.

You might try the helper method to get some fluid into the MC, but when you feel it working, I suggest switching to the Long Tube method. The advantage of the Long Tube method is: A-- it works really well and B-- it'll save your marriage.

[ThinAir]

B-- it'll save your marriage.

Gee... that's what I thought the Power Bleeder was for! It's a good thing my wife is a good sport - she's kept me for 37 years through several VWs & 914s and more brake bleedings than I can count!

[Sleepin]

Looks like that might be what I have to try.

I just replaced all four calipers with new ones from Mr. Shea, I got most of the air out, but can't seem to get them all the way. I have good pedal, but not much in the rears. I went for a drive, and can actually lock up the fronts (never could before)...but the E-brake doesn't work, (yes, I double checked the venting clearance) and when I re-bleed the brakes in the rear...more air shows up.

I need to make it to Flagstaff for Route 66 as well, I was supposed to leave early this morning (6 hour drive for me)....now it looks like I will have to wait til the Hardware store opens to buy some tubing to try the long tube method.

...gotta love last minute s#itstorms! (IMG:style_emoticons/default/biggrin.gif)

[roadster fan]

I have used the Motive power bleeder with good success. Yeah it may have saved my marriage (IMG:style_emoticons/default/biggrin.gif)

This is one of those jobs that there are alot of variables and differences from one car to the next. Be patient and follow the guidelines. Start at the caliper farthest away and work your way back to the MC. I would definitely bleed the MC before starting the calipers though. I have heard that the Proportioning valve can hold alot of air, thats is why I have a brass T, but I am sure Shea will chime in and tell us why that is not the best idea (IMG:style_emoticons/default/smile.gif)

Jim

[ThinAir]

I would definitely bleed the MC before starting the calipers though.

I got the impression that the long tube method was designed to bleed the MC as part of bleeding the calipers. Are you suggesting something else?

[SLITS]

Ernie .... crack the fittings at the MC and let it drip for a moment or gently press the pedal 1/2 way down. This fills the MC if somehow you ran it out of fluid.

If you changed the MC or moved it for some reason, make sure the pushrod from the pedal is seated in the bore. With the rubber boot, you can't see if it is outside the bore.

[davesprinkle]

I would definitely bleed the MC before starting the calipers though.

I got the impression that the long tube method was designed to bleed the MC as part of bleeding the calipers. Are you suggesting something else?

Once you start working fluid through the system, you'll purge air from the MC, so yes, the Long Tube method works on the MC. However, sometimes getting fluid into a dry MC can be challenging and I've had success using the helper method to get it started, then switch to the Long Tube to get the rest of the air out.

[6freak]

[ This fills the MC if somehow you ran it out of fluid. (IMG:style_emoticons/default/idea.gif) (IMG:style_emoticons/default/idea.gif) THIS MAY BE MY PROBLEM

[ThinAir]

Well, things have not gone well. Here's what I've done or had happen to me:

1. Bled all 4 wheels using long tube. I'm sure I had no air coming through the tube, but at the end I had no better pedal. While bleeding I could feel resistance when doing each rear caliper, but hardly any resistance from either front caliper.

2. Took it out for a drive on a very bumpy road in hopes of getting bubbles out of MC.

3. Bled right rear again using long tube. Could feel much better resistance building.

4. Bled left rear and felt really good pedal pressure starting to build, then suddenly NOTHING. I discovered that I must not have closed the right rear very well because I had fluid on the ground, but after closing it I still had nothing. The MC is not pushing any fluid through the hose that is currently on the right front caliper.

So at this point I'm thinking that the MC has had a seal fail suddenly. Is there any reason to think otherwise?

[Heeltoe914]

Just replace it and consider it a upgrade? But don’t go to the floor when bleeding!!!!!!!!!!!!!!!!


Just stand up and be a man. Sorry couldn’t resist. BAD JOKE.

[McMark]

I've definitely had MC seals suddenly fail. I've had some luck with closing all the bleeders, manically stomping the brake pedal in order to try and 'shock the system' and get stuck bubbles moving.

Bleeding brakes is my hell. (IMG:style_emoticons/default/devil.gif)