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Rt rear break line not getting fluid

This van does not pull stongly to rt or left.



brake line is clear (passes fluid) from engine compartment (box w 2 input lines from master cylinder and 4 output lines to wheels) to rear wheel when disconnected from system.



I presume that the box w 2 inputs from the master cylinder and 4 outputs to the wheels is the anti-lock system.



Could the lack of pulling be caused by the anti-lock breaking system? Could it compensate sufficiently?



Because car does not pull, I assume that only part of one circuit (presumably left front, rt rear) is blocked, thus the problem would be in the anti-lock system.



If the anti-lock system can compensate so that the van does not pull when brakes are applied, then perhaps the problem is in the master cylinder.



My next test will be to disconnect the output lines of the master cylinder from the anti-lock system (one at a time) to see if master cylinder pushes fluid to the anti-lock system.



Comments?

Thoughts?

Have you experienced this problem?



thanks

I haven’t had this happen, but doubt that the ABS has much to do with it. The rear brakes don’t do a whole lot, so maybe if one is not working it won’t pull. If there is no oil on one then maybe the proportioning valve has a problem or the line is kinked somewhere.

Thanks. I will try to find out what and where that valve is. Between the master cylinder and the breaks there is a metal box (about 4" wide, 6" long, 4" deep) with 2 inputs and 4 outputs (to calipers and wheel cylinders). I was assuming that was anti-lock system; would that be the proportioning valve?

When was the last time the brake fluid was changed?  How cold is it where you are? I doubt if it is Anti-lock related.

Perhaps I’m suffering from a stupidity attack. Fluid passes through the line when it’s disconnected? Vehicle doesn’t pull? Why do you think the brake isn’t working?

Have you tried putting the vehicle in park, jacking up the offending wheel, and setting the parking brake? Does the parking brake work? If not, shouldn’t the next step be to look at the brake mechanism? If the parking brake does work, how have you established that the problem is not a frozen caliper if it’s a disk brake or frozen brake cylinder if it’s a drum brake?

Yes, in principle, the ABS could hold a brake off, I think, but that doesn’t seem to happen often, maybe never. And probably it’d light an alarm on the panel.

It’s just barely possible that the brake hose inner lining has come loose and allows fluid to pass when not under pressure, but blocks the line when pressure is applied. That usually happens the other way round, holding brakes on after they are applied, but just maybe it could work backwards also … maybe … I guess.

I believe fluid was changed when mechanic (reliable, used for years) changed calipers roughly 2 years ago. Probably I was the one to do brakes brakes before that; I would have changed fluid then.

Miami, FL. no chance of ice in lines.

the line transmits fluid when I use an oil can to pump brake fluid from top (disconnected line from box under hood and from rt rear cylinder).

why do I think rt rear break is not working: rt rear pads were not worn but left rear pads were completely used. could not get fluid from cylinder (new cylinder, because left side cylinder had begun to leak)). disconnected line from cylinder; when brake pedal pushed no fluid was received at rt rear cylinder (fluid was received at ;eft rear cylinder).

will keep suggestion about rubber break line in mind. Will check whether parking brake works, but really that is another issue; the problem is not getting fluid.