[RESOLVED] Bleeding brake system... Not fun!

[dang]

I actually drove the E3 on the road the other day, for two blocks, since I didn't want to stray too far from home. The engine still needs attention to get it running smoother but the brakes are the bigger issue now. New master cylinder, front lines were all off the car for paint and the rear lines were cleaned out nicely with brake cleaner. Proportioning valve taken apart and cleaned although wasn't very bad to begin with.

I start bleeding the brakes and I'm having a hell of a time getting the air out. At first I could only get fluid to the first set of lines going to the front, then I tried a pressure bleeder to push the fluid. I got it to come out of the front lines on the master so I tightened them up, then got fluid out of all the wheel cylinders. The pedal goes down to about an inch from the floor. You can pump them up after about five pumps so I know it's just air in the lines, but I can't get anymore out. I bought a Harbor Freight brake bleeder that uses compressed air to create a vacuum and you connect at the caliper and suck the fluid out. I like it and it works great, but all I got our was fluid. I pulled out a lot of fluid but no air.

Ideas?

BTW, the valve on the brake booster seems fine since it doesn't affect the engine running with it connected to the vacuum port or plugged.

 

[zinz]

Motive pressure bleeder has been my go-to tool for years. With all the components having been exposed, you have a LOT of air in the system to remove. It gets trapped in all sorts of places. Some tips I can recall over the years of listening to folks on FAQ and here, is don't use too much pressure on the bleeder, no more than 15 psi (Motive has a gauge). Stomp the brake pedal several times to work the pistons and get the fluid moving in the calipers and wheel cylinders. You can also tap on the calipers and cylinders with a small hammer to entice the air bubbles to release from wherever they are hiding (surface tension is a real thing)

Many times it takes several rounds to get everything bled. I found it's easiest to get the car in the air and wheels off to allow easy access to bleeders. Go to each corner and just keep at it till the pedal firms up. If using a Motive, or other pressure bleeder, make sure the reservoir doesn't run out of fluid...then you are back to square one, because you just forced air into the system

Hope this helps. It's a PITA sometimes, and there's no way to keep from spilling brake fluid somewhere... grrrrr.

Good luck,

Ed

 

[dang]

I started with a pressure bleeder. It's the simple kind that has a valve stem attachment but I hook it up to my compressor at around 10-15psi. That got the fluid flowing through the whole system but I thought I'd try the vacuum version too. That worked well but still no change in the pedal. I guess I'll just keep going until something changes...

 

[zinz]

Stomping on the pedal will make a difference. I believe you need to jolt the system for those last few bubbles to break free from the surface tension. Tapping on the major components helps too. I like the pressure bleeder because it keeps my hands free to do all that while the bleeder is open and flowing.

I got lucky with the CS after rebuilding it. It bled out after two cycles. I'm certain you will get it.

Ed

 

[Bert Poliakoff]

Are you doing the proper bleeding rotation? Right rear Left rear Right front Left front ?

 

[JFENG]

How many pints of fluid have you run through the system? When I’m doing something major like an MC, I will have at least 2 liters of fluid on hand. Once I used over 3 liters, but in that car 3/4 of the lines were full of air. It’s enough to make me consider switching to silicon fluid.

 

[dang]

Are you doing the proper bleeding rotation? Right rear Left rear Right front Left front ?

Yes.

 

[dang]

How many pints of fluid have you run through the system? When I’m doing something major like an MC, I will have at least 2 liters of fluid on hand. Once I used over 3 liters, but in that car 3/4 of the lines were full of air. It’s enough to make me consider switching to silicon fluid.

So far about one liter. So one liter of brake fluid and about 1.2 liters of Stella Artois.

 

[Gazz]

You would love the RHD dual booster twin line set up with the nipple sequence on each wheel. Apart from that bit of useless information I presume you have checked for leaks at connections where air may be getting in.

 

[dang]

I presume you have checked for leaks at connections where air may be getting in.

Yes, you presume correctly.

 

[bluecoupe30!]

In my youth, so this is difficult to recall correctly and with sufficient clarity, I do have a recollection of struggling to bleed fluid from callipers that I eventually discovered were installed, well, upside down. Even though I intended to note the correct orientation of what came off, so it could be re-installed the same way, something was lost in translation, and after many attempts to bleed the brakes correctly, I came to the realization that the callipers were indeed backward and a simple re-orientation solved the previously futile attempts at purging air from the system. Another example of user error. Trust you have confirmed callipers are in the right place, but it is amazing that they can also be bolted up the wrong way around!

 

[dang]

Success! My son pumped the brakes up before each time I opened the valve and when we got to the right front caliper the pedal finally changed for the better. I'm pretty sure it was when I opened one of the valves that's in the middle of the caliper but not sure. The pedal is firm down only about two inches.

Back to figuring out why the motor isn't running smooth yet...

 

[Gary Waggoner]

I assume you bled the master cylinder before starting on the brakes?

 

[daddywad]

This may help for RHD cars.....

 

[Gazz]

This may help for RHD cars.....

Thanks for that Daddywad. John Castle was a tremendous resource for us RHDers. I printed out the entire back catalogue of the CS newsletter to put in a binder.