| Author |
Message |
tommylg
Samba Member
Joined: August 12, 2013
Posts: 94
Location: murfresboro tn
|
 Posted: Mon Mar 30, 2015 12:38 pm Post subject: brake bleeding and air |
 |
|
I adjusted the brakes and took it to a shop for a bleed.
They bleed one rear wheel and go to the other to bleed. when they come back to tbe first wheel, there is a lot of air - like it was never bled. No fluid leaks.
Where might the air be coming from.?
Thanks, Tommy
_________________
1971 Standard |
|
| Back to top |
|
 |
Eric&Barb
Samba Member
Joined: September 19, 2004
Posts: 24765
Location: Olympia Wash Rinse & Repeat
|
| Posted: Mon Mar 30, 2015 12:56 pm Post subject: |
|
|
Did you take the brake system apart?
_________________
In Stereo, Where Available! |
|
| Back to top |
|
|
Eric&Barb
Samba Member
Joined: September 19, 2004
Posts: 24765
Location: Olympia Wash Rinse & Repeat
|
| Posted: Mon Mar 30, 2015 1:00 pm Post subject: |
|
|
If you have stock master cylinder, you have a dual circuit one. Front circuit wheel brake cylinders are sealed off from the rear circuit, or at least should be in a properly functioning brake system.
To bleed dual circuit one need to lock up all the brake shoes against the drums by adjusting the brake star adjusters. Then bleed from circuit first and rear last. Once you have good solid pedal you readjust the brake star adjuster for slight drag at each wheel.
_________________
In Stereo, Where Available! |
|
| Back to top |
|
|
dan macmillan
Samba Member
Joined: October 19, 2003
Posts: 3110
Location: Northern Ontario, Canada
|
| Posted: Mon Mar 30, 2015 1:21 pm Post subject: |
|
|
It is not uncommon for wheel cylinders to allow air into the system when the pedal is released. Seen it many times with new ones.
_________________
Licensed Automotive Service Technician
Licensed Truck and Coach Technician
Licensed Heavy Duty Equipment Technician
CFC/HCFC/HFC A/C handling and installation license
Alignment specialist
66 Modified Manx,68 Kyote,74 Thing,74 Beetle, 76 Transporter,75 self made Double Cab,65 Meyers Manx,78Westy,68 Ghia, 79 Bradley GT2
Current projects:
Built for others:69 Manx Clone |
|
| Back to top |
|
|
vernonc
Samba Member
Joined: April 23, 2012
Posts: 681
Location: Parkersburg, WV..yes, I sold the boat
|
| Posted: Mon Mar 30, 2015 5:43 pm Post subject: |
|
|
Well, I lost track, a long time ago, of how many brake systems I've rebuilt over the last fifty years or so but I've never seen a case where air was 'allowed' into the system via the wheel cylinders; even if the cylinders were leaking fluid.
This is just my experience. 
mort
_________________
"Those who don't read newspapers are un-informed. Those who do read newspapers are mis-informed." Will Rogers
'69 sedan, low mileage, all original.....currently being 'freshened-up' for road trips and daily driving...just not every day
Freshening-up link http://www.thesamba.com/vw/forum/viewtopic.php?t=617386 |
|
| Back to top |
|
|
Mangofish
Samba Member
Joined: March 06, 2015
Posts: 27
Location: Vista, California USA planet Earth
|
| Posted: Mon Mar 30, 2015 5:54 pm Post subject: |
|
|
I had the same thing happen to me on my GMC Yukon. No matter how much (a Gallon!) fluid I put through the system I kept getting air bubbles!
I tore the Master Cylinder apart and found that one of the piston rubber cups had a tiny fold in one spot which was allowing air to get sucked past the piston cup.
I replaced the Master Cylinder and after a quick system bleed everything was good. |
|
| Back to top |
|
|
kamesama980
Samba Member
Joined: June 22, 2014
Posts: 323
Location: Columbus, IN
|
| Posted: Tue Mar 31, 2015 6:01 am Post subject: |
|
|
bad piston in the master, bad wheel cylinder, improper bleed method, allowing the reservoir to go dry.
_________________
-Russell
"You don't get to blame me for how I fix what you break"
1970 VW Beetle
1994 Pontiac Firebird
2001 BMW R1200C
2003 Subaru Baja |
|
| Back to top |
|
|
|
