Master Cylinder Leak
Thread Starter
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Senior User
Joined: Aug 2010
Posts: 191
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From: Eastern North Carolina
Master Cylinder Leak
Hello:
I developed a leak around the cap gasket on my master cylinder, '81 F-100. First I did a quick wipe down of the contact surfaces, didn't help. Then I replaced the gasket, didn't help. Then I noticed the contacting surface on the master cylinder was rough with corrosion. I lightly sanded and emery clothed it, big improvement. It is holding up fine with the "in the garage-pedal pump" test. I haven't put any road time on it yet.
Have any of you found this type issue with the old trucks?
Thank-you for reply.
I developed a leak around the cap gasket on my master cylinder, '81 F-100. First I did a quick wipe down of the contact surfaces, didn't help. Then I replaced the gasket, didn't help. Then I noticed the contacting surface on the master cylinder was rough with corrosion. I lightly sanded and emery clothed it, big improvement. It is holding up fine with the "in the garage-pedal pump" test. I haven't put any road time on it yet.
Have any of you found this type issue with the old trucks?
Thank-you for reply.
Thread Starter
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Senior User
Joined: Aug 2010
Posts: 191
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From: Eastern North Carolina
Thank-you all.
Now, I've found fluid leaking inside the cab from around the push rod. I guess I have a little job to do.
I may be back here for some more wise advice.
Any thing I should be aware of before doing my first master cylinder replacement. I've got the instructions on the Auto Zone site-manual brakes: http://www.autozone.com/autozone/rep...04bef6#hd1-1-1
Is there any way I can bleed the system without a helper?
Thanks again.
Now, I've found fluid leaking inside the cab from around the push rod. I guess I have a little job to do.
I may be back here for some more wise advice.
Any thing I should be aware of before doing my first master cylinder replacement. I've got the instructions on the Auto Zone site-manual brakes: http://www.autozone.com/autozone/rep...04bef6#hd1-1-1
Is there any way I can bleed the system without a helper?
Thanks again.
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Senior User
Joined: Nov 2010
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From: Air Capitol, KS
I just finished replacing the power booster and master cylinder a couple weekends ago. I bled the brakes two-man, but I hear you can do it one-man if you get one of those brake bleeder pumps. Make sure your power booster is good before you swap out the master cylinder only. It's a lot cheaper to get the booster/master cylinder as a pair than buying them separately, and you'll be in there again if the power booster is not in good shape.
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Bench bleed the master cylinder first -don't run out of fluid. I've got a couple of different lengths of 1" x 2" wood that I wedge between the seat and the brake pedal to work the brakes. I also use a brake "pedal jack" that I bought from Snapon a few years ago.
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Joined: Apr 2009
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From: Illernois
You can air bleed it. Doing it this way will allow you too bleed brakes on your own.
What you do is start at the brake thats furthest from the master cylinder. Crack open the bleeder bolt on the caliper and get it so it has a steady drip and continue to let it just sit and drip for ten minutes. After ten minutes tighten the bolt back down so it doesnt drip and continue on to the next furthest brake. Do this until you get all four done.
Remember to keep checking the master cylinder for fluid level, never let it get too low.
This is a easy way for one person to do there brakes and get a nice hard pedal when done.
What you do is start at the brake thats furthest from the master cylinder. Crack open the bleeder bolt on the caliper and get it so it has a steady drip and continue to let it just sit and drip for ten minutes. After ten minutes tighten the bolt back down so it doesnt drip and continue on to the next furthest brake. Do this until you get all four done.
Remember to keep checking the master cylinder for fluid level, never let it get too low.
This is a easy way for one person to do there brakes and get a nice hard pedal when done.
Postmaster
Joined: Apr 2008
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That's actually called a gravity bleed, least that's what I know it as. Works in most cases, but not always, sometimes the proportioning valve will trap air bubbles that only vacate the premises when pressurized fluid pushes them out.
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Senior User
Joined: Aug 2010
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From: Eastern North Carolina
Thank-you all the the help.
I got my master cylinder in today. Everything seems OK, but the pedal travels a little farther before I get braking. Could the new MC simply have a little more travel than the old one? It holds and doesn't sink to the floor, just requires a little more movement before I feel firmness and braking.
I got my master cylinder in today. Everything seems OK, but the pedal travels a little farther before I get braking. Could the new MC simply have a little more travel than the old one? It holds and doesn't sink to the floor, just requires a little more movement before I feel firmness and braking.