Another ($3%6&^!!) brake bleeding post

[eholster]

I have slowly working my way through the brake system on a '79 SC. I've had it almost two years and began R&R on hydraulics about a year ago. When purchased it was apparent it needed a few things - front brake hose were shot, right front caliper was sticking, etc. It quickly became chasing... I replaced front brake flex lines and freed up the caliper then experienced MC failure so replaced that (yes, I bench bled it). I have repaired / replaced and bled out quite a number of brake systems so this was not foreign territory... but was never able to get a firm pedal, in fact it was so bad I was hitting the stop / floor when doing a panic stop.
Waiting for a rainy day (which doesn't take long here in Seattle), last weekend I installed the PMB front calipers I had sitting on the shelf for many months, and figured after these and another bleed all would be well. 1 quart, 2 quarts, and finally 3 quarts later and I still had no pedal...
After purchasing another gallon of fluid I pressurized from the reservoir... I built a Phoenix Systems type bleeder to pressurize from the caliper (pressure sprayer, Schrader valve and a few fittings from the hardware store - seeing about 20 PSI)... results are about the same as before.

- I did bench bleed the MC when installing.
- When car is off I can pump up the brakes and get resistance / pressure, but after I tun the car on the pedal sinks to the stop and brakes will not pump up.
- No fluid leaks have been found - reservoir stays full
- On rear when using my homemade device to reverse bleed from the calipers I'm not seeing air, but when vacuum bleeding at the caliper I do see a fair amount, but am figuring this to be pulling in form the hose end or through threads.
- Tomorrow morning I am going to see if PMB can overnight the rear calipers and I will replace those along with rear flex lines.

Does anyone have additional input on getting a good, solid pedal and braking performance?

Thanks in advance!

[mreid]

Sounds like a bad master cylinder. Don't assume it's good just because you replaced it. If you pressure bleed from the reservoir there's no need to bench bleed.

[eholster]

That's what I was afraid of... What a pisser, on both the time and the money!

Now I know what I'm doing over the holiday break!

[pete3799]

Just to be sure........bleeders are facing up?

[eholster]

Oh yeah, they are indeed.

[drl911]

After I recently rebuilt my calipers I had similar situation. Try loosening the caliper bolts (not remove, just loosen) and then while bleeding smack the calipers rather hard with a big rubber mallet. It worked in my case by dislodging pockets of air trapped/sticking inside the calipers.

Good luck!

[eholster]

One other thought I had - to get the pads installed I pushed the pistons back. I recall reading somewhere the bleeding can benefit from pulling the pads, blocking with thinner strips of wood, and having another go at it.
Regardless, it does sound like I will need another MC.

Thanks.

[midnight911]

do two-man bleeding, not pressure bleed. I'm a big fan of pressure bleeder but believe me, two-man bleeding is better and sure.

[Tidybuoy]

I bought a brand new ATE master cylinder after replacing all 4 calipers with PMB rebuilts. I could not get any pressure after about 15 bleeds and then I took to a shop for additional bleeding. It was determined that my brand new master cylinder was bad.

When the new master cylinder came, I bench bled but I did a little differently. I put the whole master cylinder in a jar of brake fluid and pushed the plunger until all air was removed. I wiped it down, installed and cleaned with lots of soapy water.

My brakes are now firm and working perfectly!


p.s. the shop recommended that I both power bleed and manual bleed and told me to do the manual bleed slowly (i.e., when pumping up, pump slowly).

[CountD]

I also replaced the MC ('75 S) and have had no luck in getting any pressure whatsoever. I have moved on to other parts of the project in hopes some miracle happens, as I tried to bleed the system for a day using every means possible...

[eholster]

I picked up a new MC yesterday - thank you John Walker! - but unfortunately missed the FedEx guy at work today so will get the calipers Thursday.
I'll start with replacing the master tomorrow then get the rear calipers installed and work it from both ends on bleeding. Err, something like that...

[boissymeis]

I recall reading somewhere the bleeding can benefit from pulling the pads

[eholster]

I think found the root of my brake issues -

A split plastic fitting going into the master cylinder.

Discovered about 5 minutes before the local shops closed... of course.

[James Brown]

hummm, how are they now? or have you removed the M/C already. I always push as hard as i can on the peddle after bleeding. real hard and hold it. if something fails i want it to fail in the garage.

[mreid]

That fitting is not on the pressure side. I doubt it is the real problem, but hope it works correctly when you put it back together.