Front Caliper Lower Pistons Not Releasing

1985 B21FT.

Replaced both front calipers with rebuilt; front drivers side not releasing all the way - after driving a bit the wheel heats up and you can feel the car won't glide like it should.

Popped out the brake pads and the lower two pistons will not retract together - if you push in on one, the other pops out, but if you hold one the other cannot be forced back in. Uppers are fine. Also the bleeders for the lowers don't bleed much.

I loosened the lower line and the pistons both retract normally, with fluid squirting out at the nut. Same if I open the bleeders. So the fluid is not flowing back to the MC.

Suspected it might be the junction block, but reading here it seems like this is not a failure mode associated with that fine part. I find it kind of hard to believe the line would stop up enough to prevent the brake from releasing, but could it be anything else?

You could crack the fitting on the inboard end of the flex line and see if the hose is swollen shut.

Internally swollen hoses are common.

Make sure the master is retracting fully. You could check that by loosening the nuts holding it onto the booster and let it float a bit away from the booster. Get the brakes binding first, then see if the pistons retract when you do that.

I don't know why this would change if you didn't work on the master, but it is not hard to check.

hiperfauto said:

Internally swollen hoses are common.

Click to expand...

Used to be a 140 thing, but I guess the 240s are that old now and needing flex hoses too.

While you're at it a spritz of Tri-flow in the ignition keyway because the factory sheet chicken fat grease is probably dried up as well ...

hiperfauto said:

Internally swollen hoses are common.

Click to expand...

Roger that, makes sense. The flex lines are all old. I was able to crack all the fittings back to the junction block; inboard of the flex line I got no juice when I gave the brake pads a squeeze, but outboard of the flex line I got fluid when I loosened the fitting and did the same.

I'll get new flex lines on order. Fittings are all pretty clean.

May be a while before I follow up, but I will do so.

FCP sell Techna-Fit braided steel hoses very reasonably.

https://www.fcpeuro.com/Volvo-parts/244/Brake-Hoses/?brand=Techna~Fit&year=1985&m=67&e=876

hiperfauto said:

FCP sell Techna-Fit braided steel hoses very reasonably.

https://www.fcpeuro.com/Volvo-parts/244/Brake-Hoses/?brand=Techna~Fit&year=1985&m=67&e=876

Click to expand...

Yessir, just ordered four of them.

Your car takes 4 front hoses and 2 rear. It's a good idea to change them all if they're the same age.

hiperfauto said:

Your car takes 4 front hoses and 2 rear. It's a good idea to change them all.

Click to expand...

Right - that thought did occur to me. I'll replace them all and will only have to bleed the whole system once that way....

Yes sir, swollen hoses. Nothing else.
Good luck with bleeding. Still not the easiest way volvo did build.
Good night, Kay