79vetter

Has anyone else had trouble getting it to seal on the MC? It very slowly loses pressure after I pump it up. I have the newest one with the metal plate on top. I have a C-Clamp and have tried it with and without a 2x4 on top. I have tried lower pressure and higher pressure w/ the C-Clamp on the M/C.
Any other suggestions?

rafalc

I did the same thing as you, 2x4 on top and C clamp in the center. At first I was losing pressure until I tightened the C clamp more

doorgunner

Just wondering......did the adapter have any kind of sealing gasket?

carriljc

from on old inner tube on my home-made bleeder, with a metal plate, and a c-clamp. I can pressurize that thing as high as I want and it won't leak as long as I set it up properly.

Indiancreek

You can put a flat sealing surface on the master cylinder with a hand file by keeping it flat on both sides of the cylinder while filing. Make sure you get ALL the shavings out before you fill with fluid. I resurface all new cylinders on my head resurfacer while they are still dry and pressure clean them afterward. PITA but takes less time than fighting with one that has a poor seal. Also helps for a better seal with the cover.

pltmgr

All my adapters have a rubber sealing surface on them.. I always use clamp/clamps. Had a non Vette new master cylinder one time that wouldn't seal (leaked fluid from top as well).
Placed in upside down on a piece of sandpaper on a solid level surface and moved it in a circular motion. No more leaking.

Gordonm

I did similar. Just a hunk of 1/4 inch flat plate steel. Drilled and tapped with a fitting and a rubber seal. C clamp and I can pressurize it with whatever psi I want. Never failed me yet.

4SPDL81

I had to fit 3 Bessey woodworker clamps on the plate in order to get a good seal...however, too much clamping force and it would not seal...not enough clamping pressure and it would leak...somewhere in between was just right....Once I had a good seal, bleeding the calipers was easy and I now have a firm brake pedal....The Motive Power bleeder is a good unit but the aggravation factor for getting it to work properly is certainly way up there....

CA-Legal-Vette

Just to add to what the others have already said, I've never had much luck with a single c-clamp, even with the 2X4 added. Two clamps just work better even with the new aluminum plate adapter. The Motive is a great tool but certainly not without limitations.

79vetter

I went and bought a 2nd C-Clamp to have 2 on there at once and it still has that slow leak.

Can I still bleed the brakes even if there is a slow leak?

jnealg

There is a hose/wire clamp on the firewall right above and behind the mc. Mine wouldn't seal until I bent it enough to push the adapter back about 1/4 inch. Once I did that it sealed great even with the old chain and bolts. I haven't tried it with the c clamp yet but I think it might work better with one clamp over each reservoir.

CA-Legal-Vette

Yes. Just won't be quite as fast and you'll have to get up and pump it more often.

C6DuffMan

I've had good luck with mine. Here is my setup.

But, this pic was taken while trying their chain and wingnut setup. I later bought a second screw clamp and never had a seal problem.

I always made sure each clamp is centered over each MC reservoir.

CA-Legal-Vette

DuffMan's pic reminded me of a qualifier for my above "yes."

If you put brake fluid in your Motive, then the answer is no. The air will leak out and the fluid will overflow. I use my Motive without fluid and just keep topping off the fluid in the M/C. You have to make sure that you never run the reservoir dry but at least leaks become an annoyance rather than a disaster.

TWINRAY

The C Clamp has to be TIGHT. I pump the unit to 7-8 pounds. Yet there have been instances where I thought it was sealed up good and it leaked down on the frame and onto the floor before I caught it. Now I fabracated a "catch box" made up of cardboard and paper towels under the MC and view it frequently during the bleeding process.