C2 Brake Bleeding Frustration.

[Ralph B.]

I recently replaced my rear cross over brake line (for cosmetic purposes only) in otherwise a perfectly operating and newer brake system.

My problem is I'm having no luck at all bleeding either one of the rear brake calibers.

I have repeatedly tried gravity bleeding, one man vac pump and the Mrs. working the pedal for the last couple of days with no luck at all ----- no fluid or even air bubbles visible!

I re-filled the rear section of the MC with fluid which emptied when I replaced the rear cross over line which I assume is normal, the front section is still full as it should be; however the fluid level in the back section has not reduced at all throughout my failed bleeding attempts described above.

At this point I'm not sure what to do ???? ----------- I'm leaning towards removing the rear brake line at the MC and at the junction of the rear cross over and blowing some compressed air through it to see if the line is clear?

Is it possible that the problem is in the MC?

Should I consider removing the MC and "bench bleeding" it? ------- I have never removed one of these before, but it seems straight
forward?

I would appreciate any ideas or recommendations.

Thank you in advance,
Ralph PS: this is a 1966 application with power brakes and DOT 5 silicone fluid.

[Edward J.]

Re: C2 Brake Bleeding Frustration.

Ralph, If the master cylinder went empty when replacing the rear line, bleeding the master cylinder would be in order first,You'll need a bleeding kit that comes with a new or rebuilt master, which is just a coupe of rubber hoses and the plastic fittings the scew into the master.maybe your local parts store maybe able to help you out with this. If your car is a power brake car its very easy to remove the master cylinder. it just the two lines and the two nuts that hold it on. if its a manuel brake car theres a pin and clip under the dash that has to be removed from push rod.

Once the master is bleed re-install and start the bleeding process, bleeding the r/rear first I bleed he out board fitting first then the inboard fitting last, then bleed the other side .

If you need help with the master cylinder bleeding let me know? I can explain.

one other thing is make sure the fitting are really tight in the rear, if there is a leak of any sorts you can draw air into sytem while pumping.

[Ray G.]

Re: C2 Brake Bleeding Frustration.

Hello Ralph;
Suggestions;
The brake pedal travel will be restricted by the fact the front brakes are not being bleed at the same time as the rear.
Silicone fluid is more viscous and flows slower than Dot 3.
Your description sounds like there may be a restriction in the line or tee before the rear crossover line. (no fluid at either rear caliper)
We like gravity bleeding because less fluid is used in the process and air bubbles are not introduced into the system.
The vacuum pump should help the fluid flow.
If you use a helper, make sure the pedal is pumped slowly.
Ray

[Terry M.]

Re: C2 Brake Bleeding Frustration.

I think "bench bleeding" of the master cylinder is needed.

I wonder if one could "bench bleed" it in the car. Disconnect the brake line to the rear system and install the fitting with the rubber hose back to the master cylinder reservoir and pump the brake pedal. I have never tried this and the functioning front brakes might prevent a complete stroke of the master cylinder. I would be inclined to try it if for no other reason than to see if it worked.

[Edward J.]

Re: C2 Brake Bleeding Frustration.

Terry the only problem would be it can make a mess if the hose pops off, sometimes those hoses leak also , I suppose a big enough towel under the master cyl. might help.

[Larry M.]

Re: C2 Brake Bleeding Frustration.

I think "bench bleeding" of the master cylinder is needed.

I wonder if one could "bench bleed" it in the car. Disconnect the brake line to the rear system and install the fitting with the rubber hose back to the master cylinder reservoir and pump the brake pedal. I have never tried this and the functioning front brakes might prevent a complete stroke of the master cylinder. I would be inclined to try it if for no other reason than to see if it worked.

I have done this without any issues. Certainly worth a try!

If this does not work, I would recommend buying a MOTIVE Brake Pressure Bleeder and use this to pressure bleed the system. Not that expensive, and highly recommended by just about everyone who has tried it. Google the name for a local distributor, or check Corvette Central (or other similar suppliers) catalogues.

Larry

[Domenic T.]

Re: C2 Brake Bleeding Frustration.

This is why I built a preasure bleeder.
You have to have a wife that will put up with the grump that this makes out of us.
My tank bleeds from bottom up pushings the bubbles up to and thru the master cylinder at no more than 15 PSI so the bubbles don't compress.
It's a one man job and you just have to cover the top of the MC (not air tight) and make sure it doesn't over fill.
It sounds like a lot of work but your all smiles with no mess if your lucky.
The tanks are usually thrown away by exterminators or air condition people and the guage and hardmare are cheap along with the clear neoprene tubing that lets you moniter for any bubbles coming out of the tank.
What makes it handy is that you can do your fluid flush that is required and rarely done to protect the system from moisture.
In a long run it saves time, parts, and money.

DOM

[Terry M.]

Re: C2 Brake Bleeding Frustration.

Yes, a mess is a risk, but at least he has DOT5 -- no paint removal, only paint issues ar if repainting in the future.

[Ralph B.]

Re: C2 Brake Bleeding Frustration.

Thank you all for the great information -------- I will let you know know how I make out.
Ralph

[Bill M.]

Re: C2 Brake Bleeding Frustration.

Do you have the rear jacked up? Gravity bleeding should work if the car is level...

[John L.]

Re: C2 Brake Bleeding Frustration.

Ralph:
You did remember that each rear caliper has two bleeder valves right? Recently, I forgot about this, even though I had been doing this for years (after an hour or so, I woke up).
If not, then I would bleed the master cylinder as discribed, before bleeding the rear calipers.

[Ralph B.]

Re: C2 Brake Bleeding Frustration.

The car is up on jacks and perfectly level and I did notice there are bleeders on the inner and outer side of the calibers.

I have repeatedly worked both RH and LH calibers and all the bleeders (inner and outers) using all three bleeding proceedures with effectively no
fluid or air bubbles at all.

I also added new bleeders which, as expected, did not help.

I plan on removing the rear feeding brake line from the MC and also at the RH rear junction block then carefully funnel some fluid into the line at the MC end to see if I get a flow of fluid exiting out. If this checks out OK (and I expect it will) I will then suspect the MC as the problem (as appreciatively recommended) and attempt to remove and perform the bench bleeding process; however, I may be tempted to re-attach the rear line and blow some low PSI compressed air through from the MC end to see if I can pick up any air leaks, but not sure that's a good idea.

As I pointed out, I have never removed a MC and or performed a bench bleed before but I think I can figure it out and hopefully this will then fix the problem ??????

Thank you all for your ongoing help,
Ralph

[Mark P.]

Re: C2 Brake Bleeding Frustration.

I replaced the MC on my 65 and the Motive bleeder worked really well. It was recommended on this discussion board and I now use it for all my cars, new and old.

[John C.]

Re: C2 Brake Bleeding Frustration.

I have done this without any issues. Certainly worth a try!

If this does not work, I would recommend buying a MOTIVE Brake Pressure Bleeder and use this to pressure bleed the system. Not that expensive, and highly recommended by just about everyone who has tried it. Google the name for a local distributor, or check Corvette Central (or other similar suppliers) catalogues.

Larry

Hey Larry, I looked on line at the "Motive" bleeders. There were several different models listed. Which one is going to have the necessary fittings to work with a P/B '65??
JC

[Larry M.]

Re: C2 Brake Bleeding Frustration.

Hey Larry, I looked on line at the "Motive" bleeders. There were several different models listed. Which one is going to have the necessary fittings to work with a P/B '65??
JC

John:

Motive has an Application Guide on their website. Try this:
http://store.motiveproducts.com/adapters-c3.aspx Then select APPLICATION GUIDE.

Appears either the # 1119 or #1105 is what you need.

Larry