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1989 Volvo 240 Brake problem

I just changed the front calipers, rotors and the flexible hoses. I used the Haynes manual sequence to [wo]manually bleed the brakes (meaning my wife depressed the petal).

When the engine is OFF the petal is firm and feels normal. As soon as I start the engine, the petal drops half way to the floor. The car brakes, although I have not pressed the petal hard. It doesn’t seem to lose pressure.

I’ve read on the internet that the problem could be 1) air in the lines, 2) bad master cylinder, 3) the master cylinder needs to be bleed because I lost all the fluid when I changed the calipers (I don’t know how to do that), 4) perhaps the rear calipers are stuck, 5) something else?

I know this must be a common problem. It’s just not common to me. Can anyone help?


First, try bleeding the master cylinder while still in the vehicle. To do this, loosen both brake lines coming off the master cylinder then retighten them. Now have someone operate the brake pedal three or four times and then hold the brake pedal down. Crack open the two brake lines from the master cylinder to bleed any air out. Tighten the brake lines before releasing the brake pedal. Repeat this a few times, and then move on to bleeding the rest of the brake system.


Thanks “Tester”,

I will give it a try and report back. It seems like air.


Well, I ended up having to replace the master cylinder. That fixed it!