Temporary loss of rear brakes!

[julzrand]

06 Mountaineer/V6/AWD. - no warning lights of any sort ever came on. Temps in the 30's and damp outside. No fluid leaks.

After 8 hrs at work, started my vehicle & backed up about 20 ft. to load some items to take to our building next door. Noticed LOUD clunking noise & very irregular feel in braking. Thought it was odd, but parked & loaded up. Went to pull out and same thing, but now pedal was going further to floor. I could tell noise was coming from front. Drove few hundred feet to next building - problem continued. It was NOT A stopping well at all... I had some brakes, but the pedal was definitely going further to floor than ever with much less stopping power.

Called hubby (30+ yrs diesel mechanic) & our "test" was taking it over to a gravel filled area on the property. He had me pull forward quickly & hit the brakes. Did same thing in reverse. Observation: only front brakes were working. Drove back roads home in our rural town (foggy & wanted to stay away from general traffic). 12 miles to home with lots of curves & hills gave plenty of opportunities to use brakes.

ODD THING... on the way home the brakes went bacK to normal. My husband drove it since i was afraid to. He said it never repeated the brake loss after pulling out of my work driveway. I am scared to death to drive it now. I know my hubby can tackle the problem, but he has to work today so I'm hoping to get some helpful insight before he pulls it in the garage. again... NO ABS OR BRAKE LIGHT EVER ILLUMINATED ON MY DASH.

thanks!!

 

[Ornery]

If it wasn't for the "LOUD clunking noise", I would be thinking the master cylinder has a leaking seal. A LOUD clunking noise makes me think the emergency brake assembly is borked. Pulling the wheels off will reveal any obvious issues, so that would be the first thing to do. A local, reputable, brake shop could give you a free estimate, and that would give your husband a head start as well.

 

[Flag Gibby]

Just to add some additional information: There is two TSB's out there for brake issues on the 06 Mountaineers, one for the ABS system and the other for brake drag. This problem may be related to the brake drag TSB and like Ornery stated a brake shop would most likely have the correct equipment needed to troubleshoot the system and fix the defective component, unless your "mechanic" has access to all the necessary equipment.

 

[thebrakeman]

Mountaineers (and Explorers?) have a self-diagnosing system in the setup/info menus. At least run thru that. Probably won't show anything, but just check that box. I would not trust a shop to find this, unless it's repeatable. They would start with pulling of the wheels and inspecting. Your husband might as well do that before you take it in.

Check all 4 corners for any signs of abnormal wear or damage.
If any of the wheel speed sensors and/or tone wheels are visible, check for damage. Probably not...this would trip a light.
Make sure all 4 calipers are able to move smoothly on their pins. This will require pushing the pistons into the housings by pulling the housings outboard, pushing fluid back up the lines. This creates clearance between pads & rotor to check movement.

But I agree that loud front clunking is a mystery. Old ABS systems had a slower "clunk" sound when engaging. Today, it's more of a fast "buzz". But it could be the ABS valve system trying to cope with some temporary issue.

If all looks well, it could just be a fluke issue that resolved itself. Nobody likes that. If you can get a free inspection somewhere, great. But usually free inspections only involve removing the wheels and looking at the pads.