Why won't my brakes bleed

Mike67 · May 30, 2021

I agree that all the air needs to be pumped out, but if there is not enough stroke to fully engage the rear slide it could be a long drawn out process.
You can look up how much stroke (piston movement) is required and eyeball it from underneath on your pushrod.
I usually used a vacuum pump, or I'll take a clear water bottle and fill it 1/3 off the way with fluid and take a hoses off the bleeder and submerge it in the fluid. When you are bleeding it, it will confirm that air/fluid is being moved in the form of bubbles. The fluid will turn milky, don't stop there, those are very small bubbles.

ksurfer2 · May 31, 2021

I bench bled the master cylinder this morning. I was able to get the air out by bleeding the the brake pedal. However, VERY little fluid would push out of the rear brakes, also when using the vacuum pump it still pulled mostly air. The pedal is firmer, but I think there is still something wrong. Why would so little fluid push out when the bleeder valve is open and pumping the pedal?

ksurfer2 · May 31, 2021

From looking at the master cylinder in the car, it looks like it may be the same as would be in a mid 90's Dodge Dakota. The reason I say that is the top of the cylinder is taller in the back than in the front. From looking at pics, the only ones I could find that match this are from the Dakota.

https://www.oreillyauto.com/detail/...1839/automotive-truck-1996-dodge-dakota?pos=0

pnora · May 31, 2021

I prefer to put a clear tube on the bleeder and have someone pump the pedal up and hold as I crack the bleeder watching for air in the clear line. That line lock has 3 lines. Where do all 3 run to?

ksurfer2 · May 31, 2021

pnora said:
I prefer to put a clear tube on the bleeder and have someone pump the pedal up and hold as I crack the bleeder watching for air in the clear line. That line lock has 3 lines. Where do all 3 run to?

I was using clear tubing, I was also working alone, on the driver side, I could step on the pedal and watch the fluid in the line. Fluid did xome out clear with no bubbles, just very little and with a lot of effort.

Line lock has 1 line in, and 1 out to each front wheel.

kiwigtx · May 31, 2021

A kit like this can be a time saver....used one on my A100. Saved many hours.

Garngie · May 31, 2021

Garngie said:
Remove the brake hose at the rear axle and check if fluid is coming through the lines from the front of the car. The rear hose commonly goes bad and can block your brake fluid

I highly recommend you try this. It takes no more than 10 minutes and it can eliminate a lot of mysteries as to why you are not getting fluid to the rears...it sounds like you have bench-bled your MC a couple times; I doubt it is the issue.

I have had 2 out of 3 of my Mopars have the brake hose issue. Easy fix. Buy a new hose, bleed, and BOOM you're done!!

Mike67 · May 31, 2021

Just curious have you disconnected the line to the right rear caliper and see if anything pushes out ( enough to actuate) the caliper? Just to eliminate the MC or a line issue?

ksurfer2 · May 31, 2021

Mike67 said:
Just curious have you disconnected the line to the right rear caliper and see if anything pushes out ( enough to actuate) the caliper? Just to eliminate the MC or a line issue?

I did not try that, sounds like it may be. My next step.

Mike67 · Jun 5, 2021

@ksurfer2 did you make any progress?

ksurfer2 · Jun 7, 2021

Mike67 said:
@ksurfer2 did you make any progress?

I have not had a chance to dig back into it yet.

Wietse · Jun 12, 2021

I recently rebuild my Bendix master cylinder with a repair kit, after this i also wanted to bleed the brakes and flush out all old brake fluid.
The rears do not seem to bleed easy indeed and mainly pull air through the loose nipple threads, appearing the system is full of air while it is not as i got a rock solid pedal after seeing i got new fluid coming out.
The proportional valve allows full flow in normal position, the only restriction must be in the master cylinder, yet gravity bleeding it does work as i have a small continious flow coming out.
Even when pumping the brake pedal seems to do nothing for the rear brakes, i do not really understand why/how these brakes supposed to engage as both front brake and rear brake MC pistons are spring loaded.
I would assume the rear will engage first and once more brake pressure is applied the front disc brakes start to engage.

Jeff Erwin · Jun 21, 2021

I had this exact problem on my ‘71 Superbee. I replaced the front brakes completely and simply could not get the rear brakes to bleed no matter what I tried. Turned out the issue was the rubber section of brake lines were completely blocked and one of the rear cylinders was rusted. I replaced the brake lines on all 4 corners and replaced the rusted brake cylinders and the brake bleed went smoothly. The car was in storage for a number of years and water must have invaded the system because the ultimate culprit was rust.

Why won't my brakes bleed

Mike67

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ksurfer2

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ksurfer2

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pnora

FBBO Gold Member

ksurfer2

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kiwigtx

Henchman #4 and Jack-Stand Racer #2

Garngie

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Mike67

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ksurfer2

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Mike67

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ksurfer2

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Wietse

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Jeff Erwin

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