Mid 80s 240 here, maybe 220,000 miles, with brand new brakes & rotors & semi frequent service. Brake fluid level seems good.

The brake pedal ocassionally has to be pushed all the way to the floor to stop the car. It seems intermittent. The first time was a bit unnerving, so now I am driving more cautiously. Because it is intermittent, I'm guessing its not a simple pedal adjustment. I've read 2 possibilities.

1. Is bleeding brake lines to remove air simple, or costly?
2. Is a new Master Cylinder & the actual replacement (labor) costly?

Any other likely possibilities?

Thank you in advance!

 

does the brake pedal firm up after a few quick pumps? You can try bleeding the brakes but given its a sealed system, you have something wrong that needs attending to. here's what I'd do: 1) Take a look at all the lines (hard and soft) and calipers to look for any signs of fluid. You need to pop off the tires to inspect the calipers and put the car up and go under to get a good look to check all the lines. It is possible the leak can be internal to the master so you'd get a soft pedal from that.

There's a few ways to bleed a line 1) have a buddy where one operates the brake pedal and the second to open close the bleeder valve (open when pressing on the brake/close before its released up). start in the rear, go to the diagonal front then to the other rear and its diagonal front. Keep an eye on the reservoir. 2) rent/buy a power bleeder. What these do is apply air pressure through the reservoir and that pushing the fluid out when you open the valves. you need a clear hose to check for bubbles - easy enough to find at Autozone or online.

As to replacing the master - On the older cars its not a terribly hard job. Assuming no stuck fasteners etc, I'd say the parts will run $75 to $100 (assuming aftermarket) and 2 hours shop labor - so that's about $350-400 total.

 

also on a non-ABS 240, check the brake distribution block, thats somewhere down near the steering gear, both lines from the master cylinder go down to it, and it has 6 lines coming from it, 2 to each front, and 1 to each rear. one hydraulic circuit goes to half of each front brake and one of the rear brakes, the other hydraulic circuit goes to the other half of each front brake and the other rear wheel, this way when a circuit fails you still have substantial braking. only pre-ABS cars have this setup. with all those connections, there's that much more opportunity for leaks.

this junction block looks like this,
https://www.fcpeuro.com/products/vol...-volvo-1273052

it has a sensor switch on the side that lights the brake warning light if the pressure on teh two circuits is unequal. that switch can be a source of leaks.

its real important to bleed the brakes in a specific order. each front brake caliber has TWO circuits that have to be separately bled.

 

Not a mechanic here, just trying to get an idea what to expect or watch out for, or if there were a simple test.

If the brake pedal firms up after a few pumps, what does that suggest?

Thank you.

 

You can do all or you can change the master cylinder which is 99% likely to be what is the problem. The brakes have to be bled after the swap...

 

if the pedal firms after a few pumps it suggests air in the system. If there are no signs of leaks then as Lev noted, its probably the master cylinder.