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Soft Brake Pedal - Not ABS Car - Power Brake (fixed)

R

Rlover

Member
Joined
Nov 2, 2021
91 240. Not ABS brake car. Master cylinder not original but booster is 30yo

Before I replaced the Brake Booster / Master Cylinder I wanted to see from the Folks here that would know better than anyone what the cause of my soft brake peddle is?

The rotors/ calipers are new. The soft brake lines to the calipers were replaced.

The front & drivers rear when bleeding have a tremendous amount of force but passenger rear bleed caliper is a dribble. I swapped the caliper to the other side with same dribble on passenger rear.

Does this braking system have a proportional valve? Where is it located ? Does anyone have a part number?

If no proportional valve is it the master cylinder/ brake booster? Or does the brake booster have an adjustment of 25 thousandths?

Any recommendations would be most appreciated
 
You still have air in the lines.

Yes the rear proportioning valves are above the rear axle, and probably have air in them since you totally screwed up the bleeding process.
 
Redwood Chair said:
You still have air in the lines.

Yes the rear proportioning valves are above the rear axle, and probably have air in them since you totally screwed up the bleeding process.
Click to expand...

"since you totally screwed up the bleeding process"

dude this guy is new here and you're totally being a dick for no reason, maybe work on being less anti-social or something
 
VolvoLatAm said:
"since you totally screwed up the bleeding process"

dude this guy is new here and you're totally being a dick for no reason, maybe work on being less anti-social or something
Click to expand...

There's no way for me to sugar coat it, he blew the brake bleeding process.

As far as further helping he should try poking out the reluctant caliper's bleed hole with the bleeder removed and send some more fluid to flush the blockage out.
 
Does the brake pedal pump up? Barring any issues with the brake bleeding process. When bleeding these cars it's very helpful to tap on the pressure limiting valves with a small hammer. It's even good to hit the calipers a bit as well. You want to free up any bubbles.

Another thought to understand is new rotors and pads give a soft brake pedal until they are bedded in. You should actually feel the pedal firm up as you drive the first couple hundred miles or so.
 
I don?t see a place to post pictures. I used a pressurized bladder from my compressor. It bled the the fronts and drivers rear great but the passenger rear just dribbles Tried four times to bleed. Drove it around to break in the pads.

What is the correct way to flush these brakes? Since I have done it incorrectly now what should I do? The proportional valve in the rear on the axle does it have a high side to crack and bleed ?


Because it was bled I thought it maybe the booster needed to be adjusted after I found the video from IPD

https://youtu.be/Tde6xd8ezr4




Redwood Chair said:
You still have air in the lines.

Yes the rear proportioning valves are above the rear axle, and probably have air in them since you totally screwed up the bleeding process.
Click to expand...
 
dl242gt said:
Does the brake pedal pump up? Barring any issues with the brake bleeding process. When bleeding these cars it's very helpful to tap on the pressure limiting valves with a small hammer. It's even good to hit the calipers a bit as well. You want to free up any bubbles.

Another thought to understand is new rotors and pads give a soft brake pedal until they are bedded in. You should actually feel the pedal firm up as you drive the first couple hundred miles or so.
Click to expand...

No, The pedal does not recover by itself right away but does eventually. The travel of the pedal is also excessive. I thought that maybe the master cylinder had been replaced which it was but not the booster. My thought was the travel on the booster piston was not going far enough So it?s probably the proportional valve ? Is it a mechanical valve ? The proportional valve? Or just a Tee and not really a ?valve?? Thanks for your help 👍
 
Ok. I missed this post. So the proportional valve is not a ?valve?? It is really just a Tee fitting? Nothing that should be touch with on the proportional valve? The only way to solve this is to to remove the caliper bleeder?


Redwood Chair said:
There's no way for me to sugar coat it, he blew the brake bleeding process.

As far as further helping he should try poking out the reluctant caliper's bleed hole with the bleeder removed and send some more fluid to flush the blockage out.
Click to expand...
 
Rlover said:
Ok. I missed this post. So the proportional valve is not a ?valve?? It is really just a Tee fitting? Nothing that should be touch with on the proportional valve? The only way to solve this is to to remove the caliper bleeder?
Click to expand...

No, they are proportioning valves. Look above the rear axle and slightly in front of it. They are mounted to the floor of the car. It sounds like you still have air trapped in the system. I've been working on Volvo 240s since the late 70s and I still get 240s that fight me tooth and nail getting the air out of the brake system after replacing calipers etc. My 1979 242 took 4 complete cycles of the bleeding process until it had a rock solid brake pedal again. That is how a non-ABS 240 brake system should feel. With the car started if you get more than 1" of travel to the brake pedal after you take up the clearance in the system, you have a problem. I had a rear line doing what you are describing on my 78 240. I finally opened up the brake bleeder nipple a couple of turns with a hose connected to it and the other end in a jar. I then practically stomped on the brake pedal several times quickly to keep the fluid moving through the lines. After about the fourth stomp there was a loud pop and suddenly the pedal had a lot more resistance and fluid was coming out of the bleeder in the normal fashion. I don't know if there was crud in the line or just trapped air. What I do know is the Motive Power bleeder could not get the air our of that system.
 
proportioning valve

The 1991 non-ABS version is the only 240 having a plain dual manifold located directly under the master, rather than a pressure differential warning valve in the same spot on non-ABS cars. A few folks refer to this as a proportioning valve, but it isn't. And the manifold acts like a tee that you are speaking of.

But the proportioning valves are a pair of pressure regulators located just in front of the REAR axle. They can be a spot to retain air bubbles during bleeding, especially when a clog further downstream impedes the flow. Typically the clog is, as mentioned, right in the bleeder valve or just behind it in the caliper's drilled pathway. If you can't get it to flow by clearing it there, the next spot is a bit more difficult: the rubber covered flex lines between the regulators and the axle-attached hard lines.

Air can also be impossible to remove from incorrectly rebuilt front calipers; something most of us have run into over the years. The halves are mismatched leaving no path to one of the pots.
 
Just my 2 cents but every 240 Volvo I have owned the right rear caliper has always been the problem child with trapped air. Also the right rear caliper has always been the one to seize up.
I was at my friends shop last week and there was an 89 240GL in there with a "brake problem" as per the customer. Upon removing the right rear wheel it showed not only a seized caliper but a rotor that had been cut as to remove the disc from the hub. Had to advise the customer this car cannot be driven and will not leave until repaired correctly.
 
I am going to have it take the valve off the car and look at it I think at this point ?
I have already pushed a quart and a half already thru the caliper. I slammed it 4 times with my foot and every other pattern of pressure to free it. I removed the bleeder screw prior entirely and pumped it out and it did not help. I wish I could locate the part number for this valve. Everything I am finding for parts is for ABS brakes. I am hoping I can see where this being hung up and free it? I am sure this part is located in Sweden and not USA?.

Thank you for your time. 👍



.
2manyturbos said:
No, they are proportioning valves. Look above the rear axle and slightly in front of it. They are mounted to the floor of the car. It sounds like you still have air trapped in the system. I've been working on Volvo 240s since the late 70s and I still get 240s that fight me tooth and nail getting the air out of the brake system after replacing calipers etc. My 1979 242 took 4 complete cycles of the bleeding process until it had a rock solid brake pedal again. That is how a non-ABS 240 brake system should feel. With the car started if you get more than 1" of travel to the brake pedal after you take up the clearance in the system, you have a problem. I had a rear line doing what you are describing on my 78 240. I finally opened up the brake bleeder nipple a couple of turns with a hose connected to it and the other end in a jar. I then practically stomped on the brake pedal several times quickly to keep the fluid moving through the lines. After about the fourth stomp there was a loud pop and suddenly the pedal had a lot more resistance and fluid was coming out of the bleeder in the normal fashion. I don't know if there was crud in the line or just trapped air. What I do know is the Motive Power bleeder could not get the air our of that system.
Click to expand...
 
I think your onto something and I think it’s due to the booster and passenger rear being the farthest point vs all other calipers. 99-2004 Tahoes has had a known history of the passenger rear caliper getting hung up as well

If this valve needs volume / pressure to push out the air trapped ? I am wondering if a 32yo booster and 15/20yo master cylinder are up to the task? Maybe it’s nothing to do with the valve in that if it had OEM specifications on pressure it could pass the air stuck in the valve? Hmmmm……???? But with the pressurized vacuum it should have pulled the air though ….

I will keep you all posted. Thanks again for the feedback. It’s been helpful and I hope in the future this thread helps others. ��


nel621 said:
Just my 2 cents but every 240 Volvo I have owned the right rear caliper has always been the problem child with trapped air. Also the right rear caliper has always been the one to seize up.
I was at my friends shop last week and there was an 89 240GL in there with a "brake problem" as per the customer. Upon removing the right rear wheel it showed not only a seized caliper but a rotor that had been cut as to remove the disc from the hub. Had to advise the customer this car cannot be driven and will not leave until repaired correctly.
Click to expand...
 
Last edited:
Try fishing the hole behind the bleeder with a small hand held drill bit.

The proportioning valves [two] need to be changed out if the blockage is diagnosed to be there.

They are NLA afik [very expensive when you could get them] and different pressure ratings for the wagons and the sedans.

Probably to be found on eBay or in wanted.
 
Last edited:
Rlover said:
The front & drivers rear when bleeding have a tremendous amount of force but passenger rear bleed caliper is a dribble. I swapped the caliper to the other side with same dribble on passenger rear.
Click to expand...
So the passenger caliper shot out fluid like it should when on the driver's side, and the driver's caliper dribbled when on the passenger side? Not the calipers, then.

Besides the other suggestions:
Check for a crushed or crimped metal line between flex hoses and caliper.

Disconnect caliper from line, and see if it flows. This rules out the line/caliper connection.

Disconnect metal line from the flex line at the axle, and see how it flows.
This rules out the entire metal line to that side.

Disconnect flex hose from the valve to the axle connection.
This rules out a twisted or defective hose. Inside split can make a 1-way "flap" that restricts flow.

Basically work backwards toward the master cylinder, disconnecting fittings until fluid flows freely. There's your blockage.



Pic stolen from opelgt.com. First 240 rear axle pic I found.
Shows all the referenced pipes + hoses.

<img src="https://www.opelgt.com/attachments/volvo-240-rear-axle-jpg.97577/"width=800></a>


Pic stolen from 240turbo.com.
Nice general layout diagram.

<hr>
<img src="https://www.240turbo.com/240brakediagmed.jpg"width=600></a>
 
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If you get a motive power bleeder don’t go above 12psi otherwise it will either not seal or blow the seal between MC and fluid reservoir. You can clamp the cap LIGHTLY to the MC to help it seal
 
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