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1989 560 SEL ... and way too many Lincolns
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530 Posts
Discussion Starter #1
So i finally had time to do the rear calipers on my 560 as they froze up.

After install, I bled the rear brakes before starting up the car and eventually the line ran with straight fluid and the pedal was firm.

Once I started the car to take it for a test drive the brake pedal turned into smush and the brake warning light went on. The fluid was at max level.

So a few basic questions I guess ....

Do I need to bleed all 4 brake lines even though only the rear calipers were done?

Should the reservoir cap be on or off while I do it ? I had it on but have read read conflicting things on this.

Thanks in advance!
 

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Premium Member
300GD 5 dr 1987, W126 420SE, W126 560SE
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1,676 Posts
Yes whenever you work on the brake system always bleed all as air get drawn into other areas of the line.
I have a few ways I do it depending on vehicles
Good old fashioned manual foot down/up method
BUT on the 126 tell the pedal operator to NOT push pedal into floor, as his can cause master cylinder problems;
Start at the furthest point from the reservoir open valve push pedal smoothly down 3/4 of travel, hold while valve is locked up and lift pedal.
I also use a not return valve in the piece of hose off the valve...do this until clean and no air on each all 4 valves.
I also use a pump up pressure system but again use at low pressure as you can push a seal out of MC if too high
Lastly I use an oil syphon (type that pulls oil up dipstick hole) to draw fluid through system.
Care must be taken with all processes
 

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W124 400E, W126 500SE
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971 Posts
I always pushed to the floor and never had a problem - isn't that just a sign that the master cylinder was shot before? There are situations when it should work even when floored (when you loose fluid in one for example, when one circuit fails...).

I had to bleed ABS once though, it still felt soft until I've done that - but I'm not sure it can be done without a top-pressure feeding the fluid...
 

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1989 560 SEL ... and way too many Lincolns
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530 Posts
Discussion Starter #4
Thanks for the info. Tomorrow I will have a chance to do some more bleeding. This time it will have to be with a hand vacuum pump ... we'll se how it goes!
 
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