I've got a 2000 V70 283K miles and have had intermittent problems with the front brakes/caliper(s) coming on while driving. First it was the drivers side front, then the passenger side front. Got so bad the front was shaking and MPG down to 15 mpg at 60mph. Let it rest and drive again, either comes back in a few minutes or goes away. Had it on the lift and couldn't turn right wheel by hand. Went back out next day and could turn fine. I first thought it was a stuck caliper, but it's sounding more like something up the system. Ideas??

 

Did someone fill the brake fluid reservoir with oil? I have seen that done on some other cars and it causes the symptoms you mention. The lines swell and act as a one way valve when heated. Open the master cyl reservoir and look at the fluid. If you see some separation in there, or something floating you know you need to change, all 4 calipers, all 4 hoses, master cylinder and any other rubber in the system.

If the above is not the case then check just the hoses. They can come apart on the inside and act as a one way valve. if all wheels lock up this is probably not the case. if only one or maybe two lock up try this. when the wheel is locked up crack the fitting above the hose. If you don't see fluid squirt out then you know the pressure is trapped by the hose. Then crack the fitting below the hose or the bleeder. If fluid squirts out you know it is trapped by the hose. replace hose or hoses.

 

Hello, Inspect for and do what jasle says buy first take out the caliper pins and check for lube. A 7mm allen socket is required. Clean them with solvent and a Scothbrite pad. Lube with silicone grease. I'll bet that's your problem. Kira

 

Thanks for the information. It's been below freezing here, so it took me awhile. I checked both out after I had both wheels basically "locked-up". No problems with fluid or lube. However both calipers had the pistons fully extended past the rubber boots. The calipers are shot. I'm going to replace both calipers and hoses and then monitor them closely. Unless it was a fluke that both went at the same time, I'm suspecting the ABS pump assembly. Thoughts?

 

Replaced both calipers, front hoses, rotors and pads.....all seemed okay until a couple of days ago. I felt a little shaking, then yesterday it was real bad again at about 60 MPH on my way to work. After work I drove home and the shaking was gone. I can't think of anything but the ABS pump assembly. Anyone had similar symptoms and replaced this part?