olds 307 and 403

I thought it was the heavy rain, the brakes went nearly to the floor, has gone a hence my fixing the emergency brake. I kind of have the same issue as Copper had. I redid all the brake shoes, replaced both front wheel cylinders and one brake hose and bled the brakes with my daughter. Could it just need rebled or a dying master cylinder? Just weird that is only soft at times.

coppercutlass

I will say my bleeding issues where bad parts one after the other., My weak brakes are a vacuum issue. Not enough and i get only one solid pump under really light loads and a few pumps under heavy deceleration when vacuum is the highest . I did add a vacuum canister and it helped. I will be going to manual soon.

Do some stress testing in a parking lot and see what makes you loose them like many pumps of the pedal / slow mph braking etc etc.

olds 307 and 403

Vacuum should not be my issue and the brakes should be set right. Under the heavy rain, that was probably water. The pedal just goes soft on occasion and can be pumped back up.

oldcutlass

If it can be pumped back up there is air in the lines.

joe_padavano

Or, it's an internal leak in the M/C. I've had this happen where the M/C intermediate seal went bad and fluid from the front reservoir would flow into the rear reservoir instead of to the wheels.

oldcutlass

I have also, but it would do it all the time and not pump up.

olds 307 and 403

Thanks, I have had a master cylinder go bad before on a Dodge van, stayed funky. It can be good 20 times in row, then bang a soft pedal. Yes, I did try pumping it up and the pedal was normal in a couple of pumps.