Problem:

I chose this sunny day to bleed my brakes (I bought the car used a month ago and have been getting around to checking everything--the brake fluid looked bad). I borrowed a vacuum bleeder from a friend and it worked well--or so I thought. I finished up all the bleeder valves (three on each front and then one in the back), and when I turned the car on and pushed down the brake, the brake was squishy. I never let the reservoir go completely empty--or at least not at the back grommet, though I may have let the front part of the reservoir go empty. Wondering if there is any way to isolate where there might be air, or if there is something else I did wrong. I have a 91 volvo 240 with ABS. I went in order LR, RR, RF, LF.

This may be a stupid question but if I did need to drive it tomorrow, would it be a bad idea to drive it with the brakes squishy?

Thanks for the help.

Jimmy

I would not worry too much about it but be aware that you ability to emergency brake is slightly diminished.

Personally, I have only had terrible lucky with the Mity-Vac type vacuum bleeders. I am a big fan of the modified garden sprayer pressure bleeder.

My problem with the vac bleeders is not related to the bleeder, but to the fact that a loosened bleeder and introduce air into the system under vacuum. I had extensive problems with it on motorcycles...never tried it on a Volvo.

Also, did you assist the vac bleeder by using the pedal as well? If so, did you surpass the halfway mark on the brake pedal? If so, you may have entered the corrosion zone which is bad of a MC.

No, I didn't assist it with the brake. I just pumped the vacuum, then opened the bleeder valve, and then watched the fluid flow into the container. Don't see how air could have gotten in--other than if it could've been introduced if the front part of the reservoir went empty.

Again, experience only from motorcycles but the air was introduced through the threads of the bleeder. With a pressure bleeder, not a problem because the fluid is being force out the bleeder. My '79 BMW was impossible to bleed with anything except pump, pump, open, close, rinse, repeat.

Good on not using the brake pedal.

Hmmm. That could be the problem. There were air bubbles coming out into the tube that could've been coming through the threads of the bleeder valve. Is there any quick remedy for this or do I have to bleed the entire system again?

Correct me if I'm wrong, but you said that it would be safe to drive--if even for a little while?

The weakness with the vacuum system, is as you suspected, that air gets drawn in through the bleeder threads.

You could try gravity bleeding ie. open the bleeder and let fluid drip out.

You could speed up the process by depressing the pedal with the bleeder open, and holding the pedal down with lumber while you tighten the bleeder.

You could pressure bleed using a master cylinder cap with an air valve inserted and pressurized with a cheap hand bike tire pump. Keeping the pressure low so that you don't pop the reservoir and refilling between bleeds.

Using a pressure sprayer would be overkill as you are only bleeding a few ounces. And you avoid the fluid waste/contamination, clean-up and storage of sprayer.
--
1980 245 Canadian B21A with SU carb but electronic ignition and M46 trans in Brampton, Ont.

Safe is relative. I said you would not have 100% braking effectiveness in an emergency braking situation. I would drive it, especially with the ABS as a safety blanket, but I would not let my wife drive it.

If you system was working effectively before, and you got bubbles out of the bleeders without a full replacement of the fluid (how much did you go through?) you likely introduced the bubbles.

I am not saying you did not run the MC dry, but at what point in the bleeding did you get the bubbles?

The redneck pressure bleeder is made from a spare MC cap, about $5 in plumbing parts and a $6-9 garden sprayer. The only tools you need are a drill and appropriate sized bit and an adjustable wrench. Solved all my bleeding problems...almost.