hi,
Does anyone have ideas about this.
1992 volvo 240 wagon.
Suddenly when exiting on a highway ramp, my brakes went flat almost to the floor..but not quite. The still stopped the car..but was very scarey.

Had someone replace rear rotors and pads. And master cylinder, and did partial bleed of brakes... No one there to pump pedal.

Seemed fine around town..stop and go...later drove for about an hour..and again after a highway drive, brakes went 75% to floor and lots of smoke from left rear.

Mechanic then replaced left caliper, and bled brakes again..but still no one around to pump pedal.

Car again fine around town, but after 30 mins highway driving..pedal went flat again to 75%. Car still stops..but brake has to be very low.

Mechanic tried 3rd time to adjust the brakes, and did a full bleed this time with me pumping the pedal.

Car again fine around town, but after driving about 30 minutes, brakes went flat.

Consistently now.. The brakes go flat after about 30 mins of highway driving, and seem ok with stop and go driving.

Any ideas?

 

Also.. This last time, the mechanic said the bearings were bad in left rear and that there was a lot of play in the thing that holds the wheel on. Sorry.. I am not technical.. He made a few adjustments to the brakes, and the car better for a short time..but after 30 mins..they brakes again went flat.

The stopping distance when they go flat seems ok.. But something isn't right..

Also replaced front pads.

 

If your mechanic works alone and doesn't have anyone there to pump the brakes when bleeding the fluid then he should get one of those power bleeders so he can do it proprely by himself.
It sounds like the caliper is seized, I had a similar situation and replaced the rear calipers with refurbished parts. One had a complete lock up and caused a whole bunch of smoke and then the brake fluid boiled and my brake pedal went all the way to the floor.

 

I agree with Cdubbs assessment. A very likely scenario. Of course you could try dropping a Viagra in the brake fluid reservoir, but get help if the pedal stays hard for more than 4 hours

 

LOL; funniest response I think I've seen; snaps to you pal!

BTW: also agree with earlier responses..

 

check the brake distributer block under the car behind the driverside front tire. Its bolted to the frame