Brake bleeding - constant bubbles

Mark1Stu · Jul 5th, 2015, 16:19

I'm starting to regret resurrecting my Volvo project....

Just been bleeding the brakes (as per the order in the manual). When I bled the centre inner and outer RH caliper bleed points together I got a constant stream of bubbles. Doing one at a time resulted in the inner one clear of bubbles - but not the outer. Same problem with LH caliper.

I'll check again for pedal drop during constant pressure - but seemed firm when I last checked (I've had enough sight of the car for now!). So while I suspect the master cylinder is drawing air, causing the bubbles, the impression of a firm pedal suggests otherwise? Are the outer bleeds on both front calipers on the same brake line?

Just wondering whether anyone has had similar and can offer any advice.

Paul240480 · Jul 5th, 2015, 17:33

Seeing as lots of 'looks' and no replies, I'll start in the hope of one of the more experienced chipping in

I've never had your issue, akways used Ezzibleed kit . I start furthest away from master cylinder working to the closest.

Dont suppose you have a 'weep' somewhere along the lines that is drawing in air as you bleed?

Hope its an easy fix tho'.

hennabm · Jul 5th, 2015, 20:51

How does the pedal feel? Is it spongy at all? Not so much about holding pressure but more as a feel. This is with the engine offend the servo drained. If so then clamp off each flexi at a time to find out if it is air in the system.

Then clamp off the other pipe to the caliper and try and bleed the other one through.
Probably trying to teach Granny to suck eggs but I take it there is not air coming in as the bleed pipe is not tight onto the nipple?

When I bled mine I did each nipple individually on each caliper and didn't get the same problem as you're having.
I did go round each one twice to make sure and to renew the fluid as my car had been stood 8 years before I got it.

Mark1Stu · Jul 5th, 2015, 22:01

Thanks guys. I'll take your advice and clamp off the flexis in turn and see if that helps. Hopefully I'll have more enthusiasm for it tomorrow.

Thanks again.

Stuart

CWXC70 · Jul 6th, 2015, 10:01

What method are you using to bleed?

Easibleed
Vacuum bleed
or old fashioned never fail one person in the car pressing the pedal and one on the bleed screw?

Can you guess my favourite?

Clifford Pope · Jul 6th, 2015, 11:14

Did you by any chance ignore the forum advice never to press the brake pedal further down than it goes in normal braking? If so then you may well have damaged the master cylinder piston seal by running it over an unused and therefore probably corroded section of bore. The consequence is that it won't pump properly, so the pedal will never harden up, and possibly draws in air on the upstroke.

I've never heard of bleeding two nipples at once - I don't see how that could work.
Over a lifetime of bleeding brakes I've only once departed from the standard method of a bit of clear tube and a jam jar. That was when I tried an Easibleed. The seal at the reservoir leaked, and sprayed fluid everywhere.

I've always done the job single-handed. Place an inspection by the jar to light it up, crouch by the driver's door, and pump the pedal very gently by hand while watching the bubbles. When they stop, walk round and close the nipple.

You must be drawing in air somewhere on the upstroke. If there is no fluid leak on the downstroke then this must be at the master cylinder - level too low, or damaged seal.

Mark1Stu · Jul 6th, 2015, 15:10

Well, My wife was pushing the pedal while I was on the bleed nipple with a piece of tube and one way valve.

This morning, I singlehandedly used a vacuum hand pump to suck the fluid out. At which point I could hear air being sucked through nipple thread - so that appears the problem....which I got round by tightening the nipple until I couldn't hear the sucking of air - and increasing the vacuum. Pedal feels solid and holding so fingers crossed it's done.

Thanks for the advice and support chaps.

Btw, I did make the mistake of getting my wife to push the pedal to the floor - only reading up on the pitfall afterwards. Hopefully, I was lucky.

Just noticed the drivers side engine mount needs changing. Someone tell me this is a nice easy job..... : )

cheshired5 · Jul 6th, 2015, 17:09

A while back, I invested in a Sealey VS820 Pressure Bleeder.
It eliminates all the above pitfalls and makes brake and clutch bleeding/flushing a breeze as well as pressure testing your whole hydraulic system.
Truly simple one man bleeding and the best £40 I've ever spent.

Jul 5th, 2015, 16:19	#1
Mark1Stu Senior Member Last Online: Apr 21st, 2024 06:42 Join Date: Jan 2009 Location: Bristol	Brake bleeding - constant bubbles I'm starting to regret resurrecting my Volvo project.... Just been bleeding the brakes (as per the order in the manual). When I bled the centre inner and outer RH caliper bleed points together I got a constant stream of bubbles. Doing one at a time resulted in the inner one clear of bubbles - but not the outer. Same problem with LH caliper. I'll check again for pedal drop during constant pressure - but seemed firm when I last checked (I've had enough sight of the car for now!). So while I suspect the master cylinder is drawing air, causing the bubbles, the impression of a firm pedal suggests otherwise? Are the outer bleeds on both front calipers on the same brake line? Just wondering whether anyone has had similar and can offer any advice.

Jul 5th, 2015, 17:33	#2
Paul240480 Ovlovnut Last Online: Jun 5th, 2024 18:25 Join Date: May 2006 Location: Nivillac View Photos By: Paul240480	Seeing as lots of 'looks' and no replies, I'll start in the hope of one of the more experienced chipping in I've never had your issue, akways used Ezzibleed kit . I start furthest away from master cylinder working to the closest. Dont suppose you have a 'weep' somewhere along the lines that is drawing in air as you bleed? Hope its an easy fix tho'. __________________ 2004 V70 2.4SE Auto 'The Welshmobile’ 2002 Laika Ecovip 400i ( Motorhome on an Iveco 2.8TD) http://www.gitessouthbrittany.com/ http://moncopainmonchien.jimdo.com/

Jul 5th, 2015, 20:51	#3
hennabm Senior Member Last Online: May 25th, 2024 14:08 Join Date: Mar 2015 Location: Edinburgh	How does the pedal feel? Is it spongy at all? Not so much about holding pressure but more as a feel. This is with the engine offend the servo drained. If so then clamp off each flexi at a time to find out if it is air in the system. Then clamp off the other pipe to the caliper and try and bleed the other one through. Probably trying to teach Granny to suck eggs but I take it there is not air coming in as the bleed pipe is not tight onto the nipple? When I bled mine I did each nipple individually on each caliper and didn't get the same problem as you're having. I did go round each one twice to make sure and to renew the fluid as my car had been stood 8 years before I got it. __________________ 1989 240DL estate 1982 323i 2012 Punto Easy 1.4 2010 116d 2011 X3 3.0d

Jul 6th, 2015, 17:09	#8
cheshired5 Premier Member Last Online: Dec 26th, 2021 13:42 Join Date: Dec 2013 Location: Crewe	A while back, I invested in a Sealey VS820 Pressure Bleeder. It eliminates all the above pitfalls and makes brake and clutch bleeding/flushing a breeze as well as pressure testing your whole hydraulic system. Truly simple one man bleeding and the best £40 I've ever spent. __________________ 2002 S60 SE D5 Manual 209000 miles

Jul 5th, 2015, 22:01	#4
Mark1Stu Senior Member Last Online: Apr 21st, 2024 06:42 Join Date: Jan 2009 Location: Bristol	Thanks guys. I'll take your advice and clamp off the flexis in turn and see if that helps. Hopefully I'll have more enthusiasm for it tomorrow. Thanks again. Stuart

Jul 6th, 2015, 10:01	#5
CWXC70 Junior Member Last Online: Mar 11th, 2023 09:02 Join Date: Mar 2014 Location: Ashford	What method are you using to bleed? Easibleed Vacuum bleed or old fashioned never fail one person in the car pressing the pedal and one on the bleed screw? Can you guess my favourite?

Jul 6th, 2015, 11:14	#6
Clifford Pope Not an expert but ... Last Online: Yesterday 14:54 Join Date: Dec 2001 Location: Boncath	Did you by any chance ignore the forum advice never to press the brake pedal further down than it goes in normal braking? If so then you may well have damaged the master cylinder piston seal by running it over an unused and therefore probably corroded section of bore. The consequence is that it won't pump properly, so the pedal will never harden up, and possibly draws in air on the upstroke. I've never heard of bleeding two nipples at once - I don't see how that could work. Over a lifetime of bleeding brakes I've only once departed from the standard method of a bit of clear tube and a jam jar. That was when I tried an Easibleed. The seal at the reservoir leaked, and sprayed fluid everywhere. I've always done the job single-handed. Place an inspection by the jar to light it up, crouch by the driver's door, and pump the pedal very gently by hand while watching the bubbles. When they stop, walk round and close the nipple. You must be drawing in air somewhere on the upstroke. If there is no fluid leak on the downstroke then this must be at the master cylinder - level too low, or damaged seal.

Jul 6th, 2015, 15:10	#7
Mark1Stu Senior Member Last Online: Apr 21st, 2024 06:42 Join Date: Jan 2009 Location: Bristol	Well, My wife was pushing the pedal while I was on the bleed nipple with a piece of tube and one way valve. This morning, I singlehandedly used a vacuum hand pump to suck the fluid out. At which point I could hear air being sucked through nipple thread - so that appears the problem....which I got round by tightening the nipple until I couldn't hear the sucking of air - and increasing the vacuum. Pedal feels solid and holding so fingers crossed it's done. Thanks for the advice and support chaps. Btw, I did make the mistake of getting my wife to push the pedal to the floor - only reading up on the pitfall afterwards. Hopefully, I was lucky. Just noticed the drivers side engine mount needs changing. Someone tell me this is a nice easy job..... : )

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