Can't bleed my brakes - help?

[vbfronkis]

Hi all-

I am beyond frustrated at this point. I've now replaced my front and rear calipers, discs, and pads. I did the fronts two weeks ago, and they bled just fine. I just did the rears this weekend.

I can't bleed the rears to save my f%&king life.

I have a hand-held vacuum pump to draw fluid through at the bleed nipple. It holds vacuum perfectly on its own (like, put my finger over the end of all the tubing). Problem is when it goes on the nipple it lets a bit of air in and I can't get it to make a tight connection. So, that's problem #1, but I don't know if it's my entire problem.

I got fed up with the hand pump and had my wife pump and hold the brake pedal while I then opened the bleed nipple, closed it, then she let off the pedal. I then come to read more closely in my Bentley that you shouldn't press the pedal to the floor on high mileage e30s (LOL isn't that all of them?!) because you may damage the master cylinder.

Turns out, she was pushing and holding the pedal at the floor. We tried again with her pumping about 15 times (this is an ABS car) and holding, open bleed nipple, close nipple, she lets off. No dice.

At this point, with the car off the pedal is hard-ish. I can still press it down as it feel like they're air in the system. If I turn the car on, pedal goes straight to the floor. Zero resistance. I've looked for fluid leaks and bulging hoses and everything looks okay there.

I'm about to (tomorrow) run up to Bavarian Auto to get their pressure bleeder (https://www.bavauto.com/mini-brake-p...e-bleeder-0100) because I feel like that will be WAY more reliable than the vacuum bleeder.

Question is, is it possible I've damaged the master cylinder? No idea if I've damaged it or anything else. Or, there's just a shit ton of air in the system that the pressure bleeder will help with.

HELP! So GD frustrated. Been trying to bleed it for hours. Thanks!

[E30SPDFRK]

Are your rear calipers on upside down? The bleeders need to be on top in order to bleed correctly.

[vbfronkis]

Are your rear calipers on upside down? The bleeders need to be on top in order to bleed correctly.

Ha I’ve done some stupid shit, but yeah they’re on the correct sides.

[FredK]

How many times did you try the two person bleeding? When you have new, dry calipers, it takes quite a few cycles to fill them up.

When you say, pumping 15 times and holding, does that mean pumping the brake pedal 15 times, holding, then cracking open the nipple? That's not really necessary, it should only take 3-4 pumps to build sufficient pressure for the bleeding operation.

Are you getting fluid out of the bleeder, and if so, does it seem to be free of air?

[vbfronkis]

Yes, 15 times (Bentley manual says you need this many on an ABS equipped car), hold, crack open the nipple, press the pedal down, close the nipple. Barely any fluid comes out. I've been lucky to get an inch of fluid in the tubing. I can't get more than that.

[FredK]

It sounds like you might have a blockage somewhere in the rear brake circuit.

You may have a collapsed brake soft line, partially clogged knee valve, or maybe a partially clogged ABS valve.

The old rear calipers were already filled with fluid, so even if the brake system was mostly clogged, you would not be able to feel it unless you hit the brakes hard enough where you'd feel a definite bias issue. Now that you've replaced the rear calipers, it may be that it's difficult to get adequate fluid filled into the caliper pistons unless you bleed 9 million times.

This is only a hypothesis, of course. It's probably best to systematically trace the rear brake circuit from rear to front until you find the source of the fluid obstruction (if it is indeed an obstruction, vs. not bleeding a sufficient number of times).

[AndrewBird]

I had a similar issue and it ended up being the bleeders. They were the spring loaded auto-bleed type and passed very little fluid. Swapped them it for normal ones and everything went fine.

I would start by just pumping the pedal with the bleeder open until you get a good amount of fluid through. Then go back to trying to bleed. There might just be a lot of air and it is taking a while to get fluid back there.

[ButtJuice]

^ that sounds like a good option before going out to spend $.

Bleeding the clutch and brakes on my e30 was the least enjoyable part of rebuilding the car. Replaced drivetrain, subframes, etc.

[merlinfe]

Build a better brake bleeder

Here's a better brake bleeder idea for you:

Get a Bell Jar from the store. They might sell them in cases of 6 but you'll find a use for them.

Get two vacuum fittings/nipples and figure out a way to get them into the lid of the Bell Jar. I made small holes with a drill bit and enlarged the holes until I could screw in the fittings. After they are installed, seal them with silicone or hot glue, whatever, just ensure they have a good seal.

Next, get vacuum tube. Run one long length to one of the fittings/nipples on the Bell Jar. This will suck from the brake caliper so size it appropriately. Run another length of tubing from the Bell Jar to a shop vacuum. I like to use electrical tape to tape the vacuum tube to a nozzle on the shop vac.

After your set up is ready get a turkey baster and suck all the old fluid from the brake reservoir if needed. Clean the reservoir and refill with your choice of brake fluid.

After the fluid is in, go to the caliper farthest from the reservoir. ALWAYS START HERE. ALWAYS. In our case it is the right rear caliper.

Turn on the shop vac. Put the wrench on the caliper and then the vacuum tubing and open the bleeder. Let a significant amount of fluid flow from the caliper. Pumping the brakes shouldn't be necessary but it sometimes helps.

Recheck the reservoir. Move to left rear. Repeat. Move to the front right. Repeat. Finish with front left.

Then do the entire thing from the right rear again. Check the reservoir every time you finish a caliper.

This is how I bleed all my cars. Porsches, BMWs, doesn't matter. Fluid pressure is fluid pressure. The Bell Jar is the key. I can email you pictures if you want or dig up a photo hosting service so we can all have the pictures.

-Steve

[ButtJuice]

Check this out too.

http://www.e30tech.com/articles/lubemaint/brakebleeding/

[estoguy]

Have you cleaned the bleeder stems themselves? I had this problem last year, and it was gunk in them. I pulled them and ran SeaFoam cleaner through them. Then they bled fine.