[redneckhotrods]

I have a 74 jeep, I'm on the third master cylinder (the other two leaked ) I have bled gallons of fluid through it with a vacuum bleeder and still have air bubbles. I can't find any leaks, what could be causing this ??

[pepi]

If you are seeing air bubbles in the catch container, these vacuum pumps tend to do this, they suck air around the treads at the bleeder if too loose and will also suck air around the tube connected to the bleeder.

A pain for sure and a very common problem, a tube that fits snugger and pushed on, up over the flat spots you wrench on and just crack open the bleeder enough to allow fluid to exit. Will help but it is an art to use the tool even knowing that, the picture on the box and directions do not tell the whole story.

Another way is to gravity bleed the system, you say this is a jeep so I will guess the master cylinder is higher then the wheel cylinders. Just fill the MC leave the fill cap off; open the wheel cylinder bleeder and make sure the reservoir stays filled, do not let it run out of fluid. As to the bleeder give that a couple of turns out so you get a good flow of fluid.

Notice that I say a couple of turns out; that is different from the above statement where I mentioned just cracking the bleeder open.

[redneckhotrods]

Will give the gravity thing a try. thanks

[pepi]

It is very easy and will work great.

[redneckhotrods]

I gave it a try and nothing comes out.... will trade for a Yugo

[cobalt327]

Something you need to do if you want to use the pedal to bleed the air from the lines, is to wrap the bleeder fitting threads w/teflon tape. Then seat the bleeder lightly, then crack it back open. Put a tight fitting hose over the nipple running down to a jar w/the end of the hose submerged in fluid, and let gravity fill the line and wheel cylinder/caliper. Then gently press the brake pedal, watching for fluid/air coming through the line into the jar.

I kneel down next to the car so I can see the jar, and work the pedal w/my right arm. I just finished the rear brakes in my Malibu today, they work GREAT.

EDIT- Don't press so hard that the combo valve goes off center- you only need to gently push the pedal, and do not push it hard to the end of its travel.

If the combo valve DID go off center, close the bleeders and start the Jeep and press the brakes until the dash "BRAKE" light goes out. Then start over.

[adantessr]

Originally Posted by cobalt327

Something you need to do if you want to use the pedal to bleed the air from the lines, is to wrap the bleeder fitting threads w/teflon tape. Then seat the bleeder lightly, then crack it back open. Put a tight fitting hose over the nipple running down to a jar w/the end of the hose submerged in fluid, and let gravity fill the line and wheel cylinder/caliper. Then gently press the brake pedal, watching for fluid/air coming through the line into the jar.

I kneel down next to the car so I can see the jar, and work the pedal w/my right arm. I just finished the rear brakes in my Malibu today, they work GREAT.

EDIT- Don't press so hard that the combo valve goes off center- you only need to gently push the pedal, and do not push it hard to the end of its travel.

If the combo valve DID go off center, close the bleeders and start the Jeep and press the brakes until the dash "BRAKE" light goes out. Then start over.

Glad you finally got those brakes bled . Youv'e been having trouble with it for a couple of weeks if I recall correctly ...Allan

[cobalt327]

Originally Posted by adantessr

Glad you finally got those brakes bled . Youv'e been having trouble with it for a couple of weeks if I recall correctly ...Allan

There were two other threads where guys were having some real issues getting a pedal and/or bleeding their brakes, thankfully that wasn't me.

In my case, the pressure bleeding went fine, but I still didn't get back a satisfactory pedal until I did the rears. The "problem" was the rear brakes being far more worn than they should have been- as a result of them having to pull almost double duty, due to the fronts being bad.

On the rears, I just used the old fashioned way of bleeding instead of doing the pressure bleeding deal. Worked fine.

[pepi]

I overlooked the fact that you installed a new MC, so to give you better information to get the brakes successfully bled, have a read.

The simplest way to bleed the MC is to have it installed, plug the ports on the MC that the brake lines are attached to.

Fill the reservoir with fluid, now slowly pump the MC; full strokes in and out; watch the MC for bubbles; continue to slowly cycle the MC and you will notice that the length of the stroke will become less as the bubbles/air is bled out of the MC. no bubbles MC bled.

replenish the MC, put the cap on

remove the plugs and install the brake lines

Then do the gravity bleed on the wheel cylinders.

additional information plugs for the MC http://www.mpbrakes.com/products/pro...product_id=669

you could make plugs using a faired brake line about 1 or 2 inches long ,crimp and seal the end. You do not want to use a flat solid type of plug because you could damage the MCs port that the flair seals against.

[shine]

remove the bleeder and use the cone shaped attachment. it fits snug and does not leak. i also found a brass hose fitting that will fit. it works even better.