Still no brake pressure - stumped - 86 240 GL
#21
10-04-2016, 02:59 AM
#22
10-04-2016, 10:21 AM
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Volvodok yes I followed the proper bleeding sequence as stated from this website below. Regardless though, I've done hundreds of brake jobs and never once seen an air bubble so massive that the pedal sinks to the floor with complete ease as this one is doing. Yes there is air in the system still, but I personally do not believe that is my biggest issue, this is a vacuum or MC issue.
https://www.volvoclub.org.uk/faq/Bra...edingSequences
The front left caliper arrives tonight, and the NEW master arrives tomorrow, so by tomorrow evening we should have some more clear answers.
https://www.volvoclub.org.uk/faq/Bra...edingSequences
The front left caliper arrives tonight, and the NEW master arrives tomorrow, so by tomorrow evening we should have some more clear answers.
#25
10-12-2016, 11:58 AM
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Little update, the car has brakes now, the brake booster was indeed the issue. As I mentioned earlier it was a vacuum issue and not a real brake issue. With the car off I could build brake pressure, with the car running it would fall to the floor with almost zero resistance.
New brake booster installed, bleeding brakes with zero bubbles, the car stops now. However the pedal still travels too far for my liking and I think we still have a vacuum leak somewhere. (Firm as a rock with car off, travels further with car on = vacuum leak) I'm suspecting the check valve on top of the motor perhaps, or one of the lines going to the canister. The car stumbles a tiny bit when you hit the brakes, pesky leak still somewhere.
Going to dig some more tonight, but as of now the car FINALLY has brakes, and stops, but should have better vacuum. So moral of the story, trust your instincts and don't always assume brake failure is master cylinder. I can't believe how many threads I read on the net about this issue and literally only found one person who mentioned the brake booster. SIGH
New brake booster installed, bleeding brakes with zero bubbles, the car stops now. However the pedal still travels too far for my liking and I think we still have a vacuum leak somewhere. (Firm as a rock with car off, travels further with car on = vacuum leak) I'm suspecting the check valve on top of the motor perhaps, or one of the lines going to the canister. The car stumbles a tiny bit when you hit the brakes, pesky leak still somewhere.
Going to dig some more tonight, but as of now the car FINALLY has brakes, and stops, but should have better vacuum. So moral of the story, trust your instincts and don't always assume brake failure is master cylinder. I can't believe how many threads I read on the net about this issue and literally only found one person who mentioned the brake booster. SIGH
#26
10-12-2016, 03:50 PM
Really? because I believe I asked that and you said "I can pump the brakes 20 times (car off) and it makes no pressure still." Which makes me think that although at this point you have brake pressure, since you already tested this with fail, its likely a compound issue.
Perhaps a bad booster and Master cylinder. The odd thing is that with a bad brake booster, or lack of vacuum...your brakes are overly firm, not overly soft. If the pedal fell to the floor with the car off as well as on that seems like there is a huge amount of vacuum that is stuck within the brake booster somehow. But even as such, at some point they should firm up (within < less than 20 pumps)
I wouldn't call this a success just yet...
Check to make sure the valve on the booster is good, and see if you have an overall vacuum on your intake manifold.
Perhaps a bad booster and Master cylinder. The odd thing is that with a bad brake booster, or lack of vacuum...your brakes are overly firm, not overly soft. If the pedal fell to the floor with the car off as well as on that seems like there is a huge amount of vacuum that is stuck within the brake booster somehow. But even as such, at some point they should firm up (within < less than 20 pumps)
I wouldn't call this a success just yet...
Check to make sure the valve on the booster is good, and see if you have an overall vacuum on your intake manifold.
#27
10-12-2016, 04:32 PM
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Really? because I believe I asked that and you said "I can pump the brakes 20 times (car off) and it makes no pressure still." Which makes me think that although at this point you have brake pressure, since you already tested this with fail, its likely a compound issue.
On the first/old MC I could not create hardly any resistance, with the new one I could create a little bit (car off both samples) with the car ON, car never made ANY pressure, pedal soft as a feather, not falling to the floor by itself, but with very little effort. The difference from the car running to ignition OFF, is and always was a massive difference. The new booster has been the only thing that gave this car ANY brakes.
Perhaps a bad booster and Master cylinder. The odd thing is that with a bad brake booster, or lack of vacuum...your brakes are overly firm, not overly soft. If the pedal fell to the floor with the car off as well as on that seems like there is a huge amount of vacuum that is stuck within the brake booster somehow. But even as such, at some point they should firm up (within < less than 20 pumps)
To clarify, the brakes aren't firm in a bad way, the pedal feels fantastic with the car off NOW, with the car running, pedal sinks a bit too far and too easily; before the brakes grab. Again this is not air in the lines, I bled every caliper in order until there were zero air bubbles. And again, pedal never went to the floor by itself, that might have been worded badly, but it only went to the floor with zero resistance, but NEVER by itself.
I wouldn't call this a success just yet...
Not yet, but the old brake booster was certainly bad. When I compared it to the new one, the rod in the old one was floppy and after about 2 inches just flopped all over. Car had zero brakes before, now it has good brakes that aren't perfect yet.
Check to make sure the valve on the booster is good, and see if you have an overall vacuum on your intake manifold.
The check valve came brand new on the booster, so I doubt it's that but I have 2 of them now. But we're on the same page, this is definitely a vacuum issue, not air in the lines, not a MC issue either.
On the first/old MC I could not create hardly any resistance, with the new one I could create a little bit (car off both samples) with the car ON, car never made ANY pressure, pedal soft as a feather, not falling to the floor by itself, but with very little effort. The difference from the car running to ignition OFF, is and always was a massive difference. The new booster has been the only thing that gave this car ANY brakes.
Perhaps a bad booster and Master cylinder. The odd thing is that with a bad brake booster, or lack of vacuum...your brakes are overly firm, not overly soft. If the pedal fell to the floor with the car off as well as on that seems like there is a huge amount of vacuum that is stuck within the brake booster somehow. But even as such, at some point they should firm up (within < less than 20 pumps)
To clarify, the brakes aren't firm in a bad way, the pedal feels fantastic with the car off NOW, with the car running, pedal sinks a bit too far and too easily; before the brakes grab. Again this is not air in the lines, I bled every caliper in order until there were zero air bubbles. And again, pedal never went to the floor by itself, that might have been worded badly, but it only went to the floor with zero resistance, but NEVER by itself.
I wouldn't call this a success just yet...
Not yet, but the old brake booster was certainly bad. When I compared it to the new one, the rod in the old one was floppy and after about 2 inches just flopped all over. Car had zero brakes before, now it has good brakes that aren't perfect yet.
Check to make sure the valve on the booster is good, and see if you have an overall vacuum on your intake manifold.
The check valve came brand new on the booster, so I doubt it's that but I have 2 of them now. But we're on the same page, this is definitely a vacuum issue, not air in the lines, not a MC issue either.
#28
10-15-2016, 07:38 AM
Yep I guess I'd be laughing but unfortunately the assumptions of checking simple things like vacuum wasn't fully discussed. With a bad booster the engine wouldn't run to well but there was no mention of that nor was there any discussion of the MC leaking into the booster. So I guess a simple vacuum test was not done . I was also under the assumption that a leaking vacuum booster would make the peddle hard and sometimes lock up the brake system. So another lesson learned before you start throwing parts at any problem do a little diagnostic work.
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