Can't Bleed the Brakes

[FY1Cuda]

Got the third master cylinder today, and this one is only marginally better.  While bench bleeding it, when I push the piston inward it SLOWLY returns to it outermost position.  It takes about four or five minutes for it to come to rest.  I didn't think it was coming out, but when I'd leave it and return sometime later, I'd see that the piston was all the way back. I'm considering taking the guts out of it and stretching the two springs out to give them a little more umph.  Any thoughts?  I'd like to get the brakes working as soon as possible.

[Falbz]

Might work but I also had issues with those leaking from the bottom bolt too 

[FY1Cuda]

I did pull it apart and stretched the forward spring out from 1 7/16 to about 1 3/4.  When I put it back again and bench bled it, the piston would slowly return taking about 15 seconds to come back to the home position.  I dismantled it again and stretched both springs out and then bench bled it.  The piston came back immediately. So it was successful; just hope its permanent.  I called Raybestos and told the guy the story about the springs apparently being too weak.  He said he would pass it on upstairs but didn't expect miracles. And, yes that 10mm bolt (made in China) on the bottom holds it all together.

[HP_Cuda]

Well Owen I just ordered a 36283 and hoping I don't have the problems you had.

But nonetheless I guess I can go down the road you had gone.

B

[wantone]

You should be pushing with a phillips screwdriver in the dead-center of the rod area.  ONLY 1/8" at a time.    Tiny Tiny Tiny little strokes with about 15 seconds between each small push.  You're looking to get a few bubbles out only.  I did this for 20 minutes and mine was super.  PS -  I got the screw-in caps for the two lines and installed them while doing the bench bleed.

[HP_Cuda]

I'm going to do this in the car like Alan does, seem simpler and less chance of getting DOT 3 everywhere.

Already have the setup to bleed in the car and should be pretty easy! 

[1 Wild R/T]

I've used a bleeding syringe on master cylinders for many years... Fool proof... Bolt a dry master cylinder on the car, leave the lines disconnected.. put a folded terry towel under the M/C to catch any dripping fluid.. Fill the reservoirs, Take the syringe, dip the tip in the rear bowl & draw the plunger back, put the tip in the rear fluid port & with steady pressure force the fluid through the port & into the reservoir.. You'll initially see bubbles rising from the return port in the bottom of the reservoir but that will change to just fluid which will cause a low geyser on the surface of the fluid in the reservoir.... Pull the syringe, install the line, repeat on the front reservoir.. Now if you were just changing the M/C & the rest of the system doesn't need bleeding you can have an assistant get in the car, I crack both lines lose 1/4 turn, have the assistant press down on the peddle, initially the fluid will sputter but that quickly changes to steady fluid flow, tighten the lines before the peddle bottoms out & check for a firm peddle....

http://www.amazon.com/Cardone-10-5000MCB-Master-Cylinder-Bleeder/dp/B002JSM7HA

[bc3j]

I've have success using a bleeder kit but epoxy the holes in the plugs. Put the plugs in the ports and slowly hand push the brake pedal while a helper watches the mc.  Fill the mc only half way and after a couple dozens slow pushes on the brake pedal no air and a solid pedal. Easy to do. Not messy.

[FY1Cuda]

The issue I was having was that the piston wouldn't return all the way back.  The guy at Raybestos recommended the bleeding procedure of capping off both ports and pushing on the piston.
Brian, I hope your MC works right out of the box. Where did you get it?  My son saw that Mancini was having a sale and forwarded the link to me.
http://www.manciniracing.com/24whdibrmacy.html?utm_source=Carlisle+2015+Mailing&utm_campaign=MRE+HappyHemi&utm_medium=email
Now I am getting a tiny bit of DOT3 where the MC bolts up to the booster, so I'm watching to see if the rear MC seal is seeping.

[HP_Cuda]

Owen

Went the same route as you so I'm crossing my fingers.

I'll let you know but worst case I'll just send it back and no core charge.

B

[Fred]

Just changed my MC and Booster 2 weeks ago.  Got if from Napa for a 71 with disc/drum.  The MC plunger does not stick out.  Bench bled per the instructions with no problem.  Needed an 11 dollar bleed kit with tube and fittings from ORielly.

Pushed in 3/4' to 1" slowly and it returned to original postion in a second or two.  15 or 20 pushes and just fluid moved in the bowls after that.

Bled the brakes with the one man suction thing.  Filled the cup with 2 inches of fluid for each wheel, like the intructions said.

The brakes work OK, but I think the pedal is too soft.  Might need to bleed more.

[HP_Cuda]

Well looks like Raybestos MC's are junk. Had to get another one, will let you know how it goes.

B

[Falbz]

Well looks like Raybestos MC's are junk. Had to get another one, will let you know how it goes.

B

Good luck - was a PITA for something so simple.  I had to go through a bunch of M/C's to get one that worked alright.  Even now I think I have to swap to another one 

[Cudakiller70]

Good luck - was a PITA for something so simple.  I had to go through a bunch of M/C's to get one that worked alright.  Even now I think I have to swap to another one 

This is no good, what about buying a rebuild kit and doing it yourself? Just checked for 70 cuda, rockauto has 3 types. Maybe worth a try? 

[HP_Cuda]

Ordered another through another source and it works like a charm.

My theory is that the guy I bought it from had it on the shelf for quite awhile and sold it to me.

Well it's going back via Amazon so he can have it. Dang thing would only bench bleed the large resevoir and not the small.