Hello All that See This,

This is my second master cylinder out of the box and I bled them both numerous times on the bench thinking I didn't get all the air out. Well today I pulled the M/C again and was using the bleed tubes into res method. Had to go slow and wait in between pumps because the rear circuit (front plug) would keep pulling the fluid back in (bubbles too) even after you felt the front circuit stop pulling the fluid in (when the check valve kicks in on plunger return) . It felt as though the front circuit bypassed correctly at plunger return and the rear circuit's check valve was bad if it has a check valve. Does this make sense?
I was thinking of going and getting a third one but wanted to hear something positive from someone that knows more than me on this issue.

Thanks,
Russell

 

Same thing happens to me with the bubbles flowing back and forth. What I do is to run the tubes as straight up as I can before bending them over into the reservoir. Then when pressing to bleed, I hold the plunger in until the bubbles rise up high enough in the tube so as to not get sucked back down and into the MC. (Tapping the tubes helps the bubble rise a bit faster.) Also, make sure your tube to MC adapters are in tight enough so that air isn't getting drawn back through the threads as you're releasing the plunger.

You can also pinch the tube closed before releasing the plunger. This will force fresh fluid to be drawn from the reservoir on the next pump.

 

Yes, the bubbles back in forth on the rear circuit but the front circuit only came back so far (bubbles) and stopped cause of the check valve while the rear kept going. Is this normal? Shouldn't the rear circuit stop as well cause of the check valve? I get my help to pump the pedal as I listen up front. I can hear fluid squirting in the rear circuit inside res. I do the same in my jeep and hear no fluid moving in my res. I'm thinking my m/c is bad. Do you?

 

It sounds like it's working normal to me. Once installed, the fluid is going to go out and come back just like it's doing during the bleeding process. This check valve that you keep pondering over is for the sole purpose of holding fluid in the front lines to give you those one or two chances to stop the vehicle should the reservoir fluid get too low.

 

Thanks for the reply's. I've managed to get my front brakes working better than before. Problem though when I went down a dirt road to test the brakes. I was able to get the front to lock up easy but could not get the rear to lock up. I did the back up, brake. Pull forward, brake plenty of times to adjust the rear correctly. But weird thing is my emergency brake still lacks the power I use to have. It goes down further than before I did all the brake work. I'm about to take it to someone else even though I dislike the thought of it...

 

Your rear brakes are not adjusted tight enough.