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dub84
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Joined: July 12, 2012
Posts: 129
Location: Victoria
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 Posted: Mon Mar 03, 2014 6:37 pm Post subject: brake wizards... need help with a bleed. |
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Ive recently picked up an 84 tiptop from a guy who let it sit on an acreage for just over a year. When it came to me, I noticed immediately, that the brakes were hooped (pedal almost to the floor and handbrake was only thing that worked)
Anyways, inspection showed a faulty wheel cylinder... replaced it, bled all four corners using the ol' pedal pump method, a lot of air came out.... topped up the reservoir as needed.
Still spongy.
Double checked everything, bled it a second time... still spongy. Called my local brake and muffler shop and he said "Sounds like your master cylinder still has air in it... especially if it was sitting near empty in a field for a year. Crack open the lines, pump the pedal 3/4 down... close and repeat a few times. This should help."
I appreciate the free advice from a trusted shop... but I am looking at the master cylinder... and am unsure which "line to crack open" and just how long I am supposed to keep it open.
Your thoughts? I realize I will have to bleed to the system again. Should I go ahead and spend the dough on a power bleeder? Will a Power bleeder eliminate the need for me to "crack open the lines"? |
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boulderdrop
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Joined: February 06, 2008
Posts: 481
Location: Seattle, WA
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| Posted: Mon Mar 03, 2014 6:41 pm Post subject: |
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Make sure you don't have the self-adjuster in the wrong orientation. If it's backwards, it will loosen automatically. It was my problem after bleeding the shit out of the brakes and still have them act spongy.
The self adjuster is the silver-ish bar that is orientated horizontally, it has teeth on one side and "forks" on another.
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boulderdrop
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Location: Seattle, WA
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boof1306
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Joined: July 10, 2010
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Location: MELBOURNE AUSTRALIA
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| Posted: Mon Mar 03, 2014 6:46 pm Post subject: |
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| Power bleeders will only make a problem like you have worse. To bleed the m/cyl just loosen the hard line connections to the two brake circuits in the same way you bleed at the wheel. If that does not work I would start looking for a new m/cyl. If it has sat for a year (dry or not) it is probably u/s. |
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hdenter
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Joined: October 14, 2008
Posts: 2754
Location: San Luis Obispo, CA
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| Posted: Mon Mar 03, 2014 6:57 pm Post subject: |
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How are the rubber portions of the brake lines looking... Those can rot and feel spongy, too.
Hans
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dub84
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Joined: July 12, 2012
Posts: 129
Location: Victoria
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| Posted: Mon Mar 03, 2014 7:16 pm Post subject: |
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| boulderdrop wrote: |
Make sure you don't have the self-adjuster in the wrong orientation. If it's backwards, it will loosen automatically. It was my problem after bleeding the shit out of the brakes and still have them act spongy.
The self adjuster is the silver-ish bar that is orientated horizontally, it has teeth on one side and "forks" on another. |
I am almost confident those were in the correct position. I just copied the Bentley but will check again tomorrow |
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dub84
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Joined: July 12, 2012
Posts: 129
Location: Victoria
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| Posted: Mon Mar 03, 2014 7:21 pm Post subject: |
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| boof1306 wrote: |
| Power bleeders will only make a problem like you have worse. To bleed the m/cyl just loosen the hard line connections to the two brake circuits in the same way you bleed at the wheel. If that does not work I would start looking for a new m/cyl. If it has sat for a year (dry or not) it is probably u/s. |
Thanks for the suggestion... I imagine this is a lot messier than bleeding from the actual bleeders yes? I can't think of. Place to put a hose.
To confirm, crack the two hard lines connected to the MC... Place rags underneath and pump pedal 3/4 and tighten. Is there any particular order between the two?
Rubber hoses are all fine. No leAks anywhere.
I should mention I have done all of this without turning the engine on. Currently no battery. Wondering if there needs to be vacuum from engine to complete process? |
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boulderdrop
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hdenter
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Joined: October 14, 2008
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Location: San Luis Obispo, CA
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| Posted: Mon Mar 03, 2014 8:32 pm Post subject: |
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The hoses don't need to be leaking to be bad. When they get old the hoses will lose strength and bulg when you stomp on the brakes. Hence, the spongyness you feel could be the hoses stretching and bulging. How old are yours?
Hans
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hdenter
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Location: San Luis Obispo, CA
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| Posted: Mon Mar 03, 2014 8:33 pm Post subject: |
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The hoses don't need to be leaking to be bad. When they get old the hoses will lose strength and bulg when you stomp on the brakes. Hence, the spongyness you feel could be the hoses stretching and bulging. How old are yours?
Hans
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dub84
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Joined: July 12, 2012
Posts: 129
Location: Victoria
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| Posted: Tue Mar 04, 2014 12:17 am Post subject: |
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| hdenter wrote: |
The hoses don't need to be leaking to be bad. When they get old the hoses will lose strength and bulg when you stomp on the brakes. Hence, the spongyness you feel could be the hoses stretching and bulging. How old are yours?
Hans |
I do not know how old the hoses are however, they do not appear to have any cracking or look terribly old. I did not notice any bulging when the brake was being pumped. I won't rule it out though.
Can someone confirm... that in order to bleed the MC as the brake shop suggested, I just need to crack the two hard lines that protrude from the MC? Is it as simple as having towels ready....crack one nut open, press pedal 3/4, tighten nut... repeat? |
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Wildthings
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| Posted: Tue Mar 04, 2014 2:00 am Post subject: |
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If you were getting pressure/good flow at the wheel cylinders then the master has been bled, unless you ran out of fluid and filled it with air again.
Have you checked and rechecked that your shoes are adjusted properly? If loose you wont have a good pedal. |
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vanagonjr
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Joined: October 07, 2010
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Location: Dartmouth, Mass.
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| Posted: Tue Mar 04, 2014 4:30 am Post subject: |
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| Wildthings wrote: |
| Have you checked and rechecked that your shoes are adjusted properly? If loose you wont have a good pedal. |
Wildthings, would setting the hand brake and then checking the pedal make sense - i.e. - take the rear brakes "out of the system" to check if it is air (or other) vs. rear brake adjustment?
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snowsyncro
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Joined: January 11, 2009
Posts: 1557
Location: East Preston, Nova Scotia, Canada
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| Posted: Tue Mar 04, 2014 5:55 am Post subject: |
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| dub84 wrote: |
Can someone confirm... that in order to bleed the MC as the brake shop suggested, I just need to crack the two hard lines that protrude from the MC? Is it as simple as having towels ready....crack one nut open, press pedal 3/4, tighten nut... repeat? |
Yes.
The 3/4 is so you are not forcing the seals beyond the range of travel they would have seen before. Tighten nut so as not to draw air in when you retract the pedal. If there has been air in the m/c for a while there could also be rust inside. ''Spongy" can be hard to quantify. If spongy means springy, i.e. it travels a bit then eventually gets firm in one travel stroke, and this can be repeated ad nauseum, then there is air. If, on the other hand it is 'soft', meaning the pedal never reaches a hard stop until the end of travel, then there is a leak somewhere. If you are losing fluid then it is in the lines, wheel cylinders, or calipers. If you are not losing fluid it is bypassing in the m/c.
EDIT: I should add, that in over four decades of bleeding brakes on old VWs, I have never had to bleed the master cylinder as you have described, to get the air out. My girlfriend>wife is my power bleeder; she has been there through all of my VW life poor girl. Even less likely this is a problem on the T3, I think, because the m/c is tilted up and any air will naturally want to escape out the lines when you bleed. As a friend would always say: "Clever; them Germans."
RonC |
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Wildthings
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Joined: March 13, 2005
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| Posted: Tue Mar 04, 2014 9:09 am Post subject: |
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| vanagonjr wrote: |
| Wildthings wrote: |
| Have you checked and rechecked that your shoes are adjusted properly? If loose you wont have a good pedal. |
Wildthings, would setting the hand brake and then checking the pedal make sense - i.e. - take the rear brakes "out of the system" to check if it is air (or other) vs. rear brake adjustment? |
Yes, setting the hand brake would have the effect of taking the rear adjustment out of the system. |
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dub84
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Joined: July 12, 2012
Posts: 129
Location: Victoria
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| Posted: Tue Mar 04, 2014 4:44 pm Post subject: |
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| snowsyncro wrote: |
| dub84 wrote: |
Can someone confirm... that in order to bleed the MC as the brake shop suggested, I just need to crack the two hard lines that protrude from the MC? Is it as simple as having towels ready....crack one nut open, press pedal 3/4, tighten nut... repeat? |
Yes.
The 3/4 is so you are not forcing the seals beyond the range of travel they would have seen before. Tighten nut so as not to draw air in when you retract the pedal. If there has been air in the m/c for a while there could also be rust inside. ''Spongy" can be hard to quantify. If spongy means springy, i.e. it travels a bit then eventually gets firm in one travel stroke, and this can be repeated ad nauseum, then there is air. If, on the other hand it is 'soft', meaning the pedal never reaches a hard stop until the end of travel, then there is a leak somewhere. If you are losing fluid then it is in the lines, wheel cylinders, or calipers. If you are not losing fluid it is bypassing in the m/c.
EDIT: I should add, that in over four decades of bleeding brakes on old VWs, I have never had to bleed the master cylinder as you have described, to get the air out. My girlfriend>wife is my power bleeder; she has been there through all of my VW life poor girl. Even less likely this is a problem on the T3, I think, because the m/c is tilted up and any air will naturally want to escape out the lines when you bleed. As a friend would always say: "Clever; them Germans."
RonC |
Ok everyone... by the way, this place rocks... exactly why I will always drive veedubs..
In any case, had the car up on the hoist... Checked all four corners... no leaking... no bulging of hoses... even checked adjusters which seemed fine. No fluid loss... nothing dripping on my feet.
I cracked the two hard lines of the MC and bunch of black stuff came out and then clear.... I did this by pumping a few times.... pressure on pedal as suggested, crack line... pedal goes down 3/4... close the line... remove pressure of foot rinse, lather, repeat.
Now, it is stiff and the pedal travel ends a lot higher which is good.... BUT
I pump it a few times, and its stiff... I leave it for maybe 15 seconds... I pump it again, its soft-ish first pump, than stiffens. I still need to bleed the brakes again now that I have bled the master cylinder but... is that the only reason it would react this way. |
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Howesight
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Joined: July 02, 2008
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Location: Vancouver, B.C.
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| Posted: Tue Mar 04, 2014 5:43 pm Post subject: |
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Regarding:
"I pump it a few times, and its stiff... I leave it for maybe 15 seconds... I pump it again, its soft-ish first pump, than stiffens."
Aside from the double entendre, what is happening is the return springs in your rear brakes are returning the shoes to the out-of-adjustment position. I bet this symptom you describe does not happen with the parking/handbrake fully engaged.
The last place to get air out of your system is the brake proportioning valve (BPV)which is, unfortunately, at a rather high location in the brake line circuit. Vigorous pumping when bleeding will usually push any air bubbles out of the BPV without the need to bleed it separately.
Finally, front calipers have a large displacement for a small amount of travel. The springiness could be partly due to rust on the face of the caliper pistons (where they contact the back of the brake shoe), dust or dirt between the shoes and the rotor, and/or rust on the rotors. The dirt, rust and dust can result in some springiness.
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dub84
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Joined: July 12, 2012
Posts: 129
Location: Victoria
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| Posted: Tue Mar 04, 2014 7:54 pm Post subject: |
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| Howesight wrote: |
Regarding:
"I pump it a few times, and its stiff... I leave it for maybe 15 seconds... I pump it again, its soft-ish first pump, than stiffens."
Aside from the double entendre, what is happening is the return springs in your rear brakes are returning the shoes to the out-of-adjustment position. I bet this symptom you describe does not happen with the parking/handbrake fully engaged.
The last place to get air out of your system is the brake proportioning valve (BPV)which is, unfortunately, at a rather high location in the brake line circuit. Vigorous pumping when bleeding will usually push any air bubbles out of the BPV without the need to bleed it separately.
Finally, front calipers have a large displacement for a small amount of travel. The springiness could be partly due to rust on the face of the caliper pistons (where they contact the back of the brake shoe), dust or dirt between the shoes and the rotor, and/or rust on the rotors. The dirt, rust and dust can result in some springiness. |
hahahaha damn...
a few things... the van currently has the emergency brake engaged. I am not sure if this affects things. Should I be doing this with the ebrake down? Define vigorous: short spurts, or lengthy 5 or 6 times?
Finally, the callipers and rotors were serviced once I got everything up. Took the pads out, cleaned up the callipers, greased everything up...
Thanks for your help so far! |
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jwallis
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Location: Austin
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| Posted: Fri May 08, 2015 8:09 am Post subject: |
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so dub, did you ever get a stiff pedal? What was the solution? I'm basically in the same situation now. Replaced basically everything that can be replaced in the brake system incl the master cylinder and rear bearings, quite certain I got a thorough bleed, adjusted the rear adjusters so that there's significant drag, and still the pedal could be harder. Been so long since I've driven (this job took weeks) it that I don't remember exactly what the pedal's supposed to feel like...
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Kombi///M3
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Location: Vancouver, BC
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| Posted: Fri May 08, 2015 12:45 pm Post subject: |
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| jwallis wrote: |
| so dub, did you ever get a stiff pedal? What was the solution? I'm basically in the same situation now. Replaced basically everything that can be replaced in the brake system incl the master cylinder and rear bearings, quite certain I got a thorough bleed, adjusted the rear adjusters so that there's significant drag, and still the pedal could be harder. Been so long since I've driven (this job took weeks) it that I don't remember exactly what the pedal's supposed to feel like... |
Have you taken it for a drive around rhe block? Did my brakes recently and at first it was a little soft.. Bled it again and noticed more air needs to get out. Took it for a drive.. And she's good. Pretty sure you bled the farthest
wheel first. I used a bleeder pump.. Cheap and great investment.
Good luck. |
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