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'94 Taurus Gen2 rear noise - caliper?

2K views 12 replies 5 participants last post by  norite 
#1 · (Edited)
While stuck in stop-and-go traffic for a while, my right rear brake makes a musical "who, who, who" noise for a few seconds after releasing the brake, with the first three revolutions of the wheel. It doesn't make the noise when braking, or releasing when the car is cold, and the car brakes fine at all times.

It is a '94 Taurus with only 55k miles, there are no red lights on the dash. There is no rust underneath the car, but I do see a bit of corrosion on the brake line connectors leading to each rear wheel. I recall the rear brakes were serviced many years ago (10 yrs.?). The car spends most of the time parked in a cool, damp garage.

I don't know much about brakes. My guess is the caliper. What would TCCA recommend -- simple cleaning or entire replacement?
 
#2 ·
You don't have a caliper in the rear. They are drums. First thing to do is to take the drum off and inspect what's going on there. If you are not familiar(and uncomfortable with diagnosing) brake issues, your best bet would be to take it to a qualified mechanic.
 
#3 ·
Follow-up: Today I brought the car to a mechanic and had the rear brakes checked. They are disc, not drum (saw with my own eyes).

No one in the shop could find anything wrong in particular. The calipers, pads, springs and hoses all looked good. In fact, they seemed to think it had been serviced recently (no, but it has had low miles since a rear brake job years ago). The most the manager could say was to replace the rear calipers, hoses, pads and master cylinder . . . for $550!

I did nothing. I instead came home and researched the matter on the Internet. I found a link discussing the master brake cylinder that explained how moister in the brake fluid can cause uneven pressure differentials between the primary and secondary cylinders of the MBC. This condition can cause a "dragging" brake in one or more wheels.

Indeed, my brake fluid has not been changed in many years. I am going to replace the brake fluid in the master cylinder reservoir as much as possible with a turkey baster. I will circulate clean fluid by pumping the brake and replacing more fluid. I have read that most of the brake system's fluid resides in the master cylinder, and that many dealerships consider removing the reservoir fluid a "flush."

I'll keep the forum posted.
 
#6 ·
For anyone still interested, the problem was indeed the brake master cylinder.

I exchanged the brake fluid out of the reservoir as much as possible. It didn't help at all, but seemed to make the other wheels squeal occasionally in the same manner. I noticed some very fine sediment in the old brake fluid, which I know is a sign of master cylinder wear. So, I had master cylinder replaced (and nothing else). I've now waited a few weeks and haven't heard the noises ever again!

I've read that some car buffs recommend changing the the brake fluid -- at least in the reservoir -- every three years to prolong the life of the master cylinder.
 
#7 · (Edited)
For anyone still interested, the problem was indeed the brake master cylinder.

I exchanged the brake fluid out of the reservoir as much as possible. It didn't help at all, but seemed to make the other wheels squeal occasionally in the same manner. I noticed some very fine sediment in the old brake fluid, which I know is a sign of master cylinder wear. So, I had master cylinder replaced (and nothing else). I've now waited a few weeks and haven't heard the noises ever again!

I've read that some car buffs recommend changing the the brake fluid -- at least in the reservoir -- every three years to prolong the life of the master cylinder.
I flush mine every 2-3 years. Saves a lot to pull the master cylinder resivor out and refill to begin. Start with 2 quarts of un-opened fluid. See pic, this after 4 years.

And yes, G-2's some had discs. Most not. As I remember.:D

-chart-
 
#11 ·
That looks like a very handy device. Did you make it yourself or purchase it somewhere? Is that 3/8" silicone tubing with some sort of plumbing valve, mason jar, etc.?

You have devised a smart technique for flushing the brake system, with some very valuable information. Draining the reservoir first makes a lot of sense, especially since I saw how much fine metal sediment accumulates in the reservoir. I'm not able to flush my system right now, however, because it sounds like I'll have to pull off each wheel.

One last thing. Do you think the clean fluid in the reservoir ever works its way down to the calipers? I know it's hydraulic fluid and not designed to circulate, but over the course of months is there any sort of exchange of fluid throughout the system?
 
#12 ·
That looks like a very handy device. Did you make it yourself or purchase it somewhere? Is that 3/8" silicone tubing with some sort of plumbing valve, mason jar, etc.?

You have devised a smart technique for flushing the brake system, with some very valuable information. Draining the reservoir first makes a lot of sense, especially since I saw how much fine metal sediment accumulates in the reservoir. I'm not able to flush my system right now, however, because it sounds like I'll have to pull off each wheel.

One last thing. Do you think the clean fluid in the reservoir ever works its way down to the calipers? I know it's hydraulic fluid and not designed to circulate, but over the course of months is there any sort of exchange of fluid throughout the system?
Fresh fluid in the MC will only help the MC piston. Fluid flow is a one way street. My jar/hoses are some kind of plastic, scrap from work. (retired 17 years ago). Clear plastic likely better as easier to see through. Hose barbs and my valve just stuff out of my pile of used parts.

-chart-
 
#13 ·
I use a hand held vacuum pump to bleed my brakes/flush out the fluid. Very handy tool to have, and I can do it all myself.
 
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