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More air than fluid when bleeding (240)

studmuffed

studmuffed

Member
Joined
Nov 16, 2017
Location
Va
Hey all,

In my new brick project, I had terrible brakes. The failure light came on and the pedal would go straight to the floor when the car was on or off. I thought it must be the master cylinder so I went to advance auto and got one and threw it in. I don't have a shop or anything where I'm living right now so couldn't bench bleed.

When I went to bleed starting with the passenger rear caliper, barely any fluid came out but tons of air did. The bottle I was using had bubbles every time I pressed the pedal down. I repeated the process for probably about an hour or two and I still couldn't get a constant steam of fluid.

Could air be getting in just as fast as it was getting out?? I checked under the car and didn't see any drips and the brake junction box was dry.

(1988 245 no ABS)
 
I know funds can be an issue, but having something like this will make your life so much easier. And bleeding can be easily done without a helper and you will NEVER have to pump the pedal again.
Using the Motive: https://www.youtube.com/watch?v=04DZuyzAQDQ
Dave B
 

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I second the power bleeder. Most European cars I have found use the same size cap on the reservoir so you can use it with more vehicles than just volvos.

I found the rear brakes to be tricky. Air also likes to stick in the proportioning valves. I tap them with a small rubber mallet while bleeding and that dislodges a bubble or two.
 
You can buy the Motive adapter cap that fits the Volvo MC for something around $15 or less and a garden pump sprayer from a big box store will do fine for a pressure source. Just don't over do it with the pressure because you can pop the reservoir right out of the MC body. With a pressure bleeder bench bleeding the MC is not necessary.
 
Couple other things to consider:

How loose is the bleeder nipples for the fluid bleeding? Air can be sucked through the bleeder threads after and appear as bubbles. One thing you can do is take some grease at the end of a bladed screwdriver and form a continuous bead of it around the base of the bleeder to seal any air leaks through the threads. Make sure to wipe it off after you are done bleeding fluid.

How do the rubber hoses look coming off the proportioning valve on the drivers side of the car at the axle? If those have not been changed out they can swell and make fluid extraction difficult. Changing out these rubber lines on my 1975 242

14326936344_a5f4cb8519_c.jpg


14327624535_32cb37d943_c.jpg
 
The bleeder screw was definitely a little loose, so if power bleeding doesn't work I'll check that out. Also I didn't look at those lines so I'll give them a look too. Thanks

polaris said:
Couple other things to consider:

How loose is the bleeder nipples for the fluid bleeding? Air can be sucked through the bleeder threads after and appear as bubbles. One thing you can do is take some grease at the end of a bladed screwdriver and form a continuous bead of it around the base of the bleeder to seal any air leaks through the threads. Make sure to wipe it off after you are done bleeding fluid.

How do the rubber hoses look coming off the proportioning valve on the drivers side of the car at the axle? If those have not been changed out they can swell and make fluid extraction difficult. Changing out these rubber lines on my 1975 242

14326936344_a5f4cb8519_c.jpg


14327624535_32cb37d943_c.jpg
Click to expand...
 
Alright I think I am on the right track, but could use some input from more experienced TBers. I got the power bleeder all hooked up and working but the pedal feel was still awful and there was barely any fluid coming out of the rear bleeders. Sometimes, the fluid coming from the bleeders would stop all together with 15psi still in the pressure bleeder tank. Could this mean my replacement master cylinder is bad? I bench bled it this time but before I read about the proper way to bleed brakes I used the traditional foot method and pushed it all the way to the floor far too many times. I'm wondering if it either came defective or I messed it up by pushing the pedal too far too many times.

The only other thing I could think of is a clogged bleeder or a clog somewhere else in the brake system.
 
Khrrck said:
They tend to swell up internally and cause blockages (or shed bits of rubber into the brake fluid) - even if they're not your actual problem, 33 years probably means they're due for replacement.
Click to expand...

Alright, I ordered a set for the front & rear. Do you think this is the issue though? I figured I should buy them anyways since I'd like to autoX the car, but still trying to find the root cause.
 
I read this part:

and there was barely any fluid coming out of the rear bleeders. Sometimes, the fluid coming from the bleeders would stop all together with 15psi still in the pressure bleeder tank.
Click to expand...

... then I was going to say:

The only other thing I could think of is a clogged bleeder
Click to expand...

... but you beat me to it.

How is the flow if you take the bleeder all the way out of the caliper?
We've had a few "no flow" corners over the years. A few of them were bleeders full of crud that just needed a tiny drill bit and some shop air to clear the passages. One had a blockage just inside the hole in the caliper. Bleeder out and a sharp stomp on the pedal got that one flowing again. We've also had a couple of bad hoses, as mentioned by others.
 
Haven't tried taking the bleeder all the way out, I'll try that next time. Earlier today I threw in the new master cylinder, bench bled it, and I bled all 4 corners of the car and 5/6 bleeders in the front (one broke off). To my surprise, there wasn't that much air coming from the bleeders which was confusing considering my pedal was still very squishy and low on my test drive. I guess the last thing to do is to swap the new lines in and see if that gets these brakes feeling right.

One thing I noticed was that the amount of fluid coming out of the bleeders was constant between any of the bleeders, which just makes me think that the power bleeder flows less than the pedal method based on design and wasn't an issue in the first place
 
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