[awbazar]

I am experiencing a slow caliper release on the right rear disk brake of a 1993 Taurus GL. The other brakes work fine with the exception of a very slow release on the right rear caliper which ultimately overheats the rotor and brake pads if many frequent stops are made.

When bleeding the brakes, the left rear had good flow while bleeding but the right rear bleeds very slowly as if there is something restricting flow to that caliper.

I have checked the brake tubing for sharp bends and dents with no obvious restrictions noted and have ruled out the proportioning valve by cleaning it on two separate occasions and switching the right and left valve spools with no change in the right rear brake.

The slide pins on the calipers were cleaned and lubed and both rear calipers were recently replaced due to a set of burned up pads on the right rear caliper which apparently resulted from the same problem still remaining present on the car.

Something is restricting flow to the right rear caliper. I am beginning to suspect something in the ABS hydraulic unit. I don't know the internal construction of the unit but since all other parts of the brake system seem satisfactory including the left rear wheel. The only remaining individual element which would seem to affect just the right rear caliper would seem to be the ABS hydraulic unit. I do not have any engine codes showing an ABS issue but there may be none to detect.

Any hints or comments would be appreciated.

[Ricky Rocket]

I would check the flexible rubber hose to the caliper. Sometimes these will collapse on the inner layer of rubber and act just like a check valve, this will slow down the fluid flow to the caliper (the bleeding problem) and hold the pressure there because it cannot flow back (holding problem).

Good luck,
Rick

[randywrench]

I agree with the brake hose being bad, pretty common problem,
try loosening the line that goes into the hose you should have good pressure.

[awbazar]

Thank you for the tip about the flexible hose. I'll try checking the flow at the inlet to the hose and see if it looks reasonable. Since it is easy to remove, I may as well take it off and blow air through it and see if there are any restrictions or clues relative to internal damage.

Since some work was done on the car with the caliper suspended by wire from the spring, the hose may have become damaged from being twisted to an unusual position. Although the flex hose was treated with reasonable caution, I can speculate that it may have taken a hit or two in the process.

[BadA$$37]

I think everyone has already hit the nail on the head, just to confirm. A buddy of mine had the same problem on an 80s Camaro, changed the flexible line and took care of it.

[awbazar]

Thanks to the tips regarding the probable bad flex hose to the caliper, I removed the old hose and could not run a wire through it. It stopped right at the midpoint where there was a steel clamp for attaching it to the side of the strut to keep it from rubbing with suspension motion.

I installed a new flex line and the caliper bled out in a couple pedal pumps. That was definitely the clinker!

I grabbed the clamp in a vise on the old flex hose and opened it up and removed it from the old hose. There was obvious compression of the hose to an alarming degree. With the clamp off, the wire went down the full length of hose and came out the other end. The hose is basically still useful if the clamp is put back on with less grip.

Part of the problem was due to salt water running down the side of the hose and under the clamp where it contacted the hose. I scraped off a couple large rust scabs from inside the clamp which added further compression onto the hose on top of what looked like an overkill death grip to begin with.

Thanks again for the tips about the hoses. I'll hang onto the salvage job hose as a last-ditch back-up spare.