1948 - 1956 F1, F100 & Larger F-Series Trucks Discuss the Fat Fendered and Classic Ford Trucks

Bleeding the master cylinder

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Old 08-05-2010, 09:48 AM
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Bleeding the master cylinder

My brake pedal goes all the way to the floor. The master cylinder is empty. I'm not sure if some brake component is leaking. I was going to try and bleed the brakes possibly over the weekend.

I checked the repair manual and couldn't find anything on bleeding the master cylinder. However, I'd like to know if the master cylinder needs to be bled as well???

Thanks.
 
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Old 08-05-2010, 09:56 AM
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If its new you need to bleed it; I just filled mine with fluid, insert a rod in the endand pumped until there weren't any bubbles inside the two chambers; you cam also install lines that are bent so the fluid goes back into the M/C as you apply pressure with a rod. To ensure I had all the air out I pumped mine until I had almost emptied both chambers, then refilled and capped the ends until install.
 
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Old 08-05-2010, 10:01 AM
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It's not new. It's been in the truck for years. Still needs to be bled or should I just fill up the master cylinder, release all the wheel cylinders and pump until fluid comes out from all of the wheels, then recap and bleed each wheel separately?
 
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Old 08-05-2010, 10:08 AM
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Unless it went dry I don't think the MC would need to be bled, I would just do as you mentioned fill it up and bleed all cylinders one at a time; which will also flush your entire system if you fill up a few times.
 
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Old 08-05-2010, 10:09 AM
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If master is empty the fluid has gone some where.
 
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Old 08-05-2010, 10:11 AM
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Originally Posted by reg1952
If master is empty the fluid has gone some where.
That's what I'm afraid of.
 
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Old 08-05-2010, 11:58 AM
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I'm sure you'll find the leak as soon as you start pumping. Too much pumping will cause air bubbles. Fill the M/C and push all the way to the floor in one motion. Release pedal, fill again and to the floor again until the M/C is full. Hope I didn't tell you something you already know. Just trying to help. The intake looks great by the way.
 
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Old 08-05-2010, 10:42 PM
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Originally Posted by reg1952
If master is empty the fluid has gone some where.
x2 couldn't just evaporat into thin air. How long has it been sitting,couple days,weeks or years?
 
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Old 08-05-2010, 11:12 PM
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It's been sitting for a few years, plus or minus another few. Last registration sticker was 2004.
 
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Old 08-05-2010, 11:15 PM
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I've done a few brake jobs on the F1s and have never bench bled the master cylinder. Installed it dry, made new lines and starting bleeding from the right rear wheel. A couple pumps of the pedal and the line is filled.
 
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Old 08-06-2010, 02:52 AM
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Bench bleeding the master cylinder on these old trucks is somewhat more complicated than the modern dual circuit masters because of the way that the distribution block is attached. It would be necessary to either make 3 separate short lines that go from each port back to the reservoir for bleeding or to find some inverted flare plugs and plug two ports and just have one return line to the reservoir. Single circuit master cylinders are much easier to bleed than dual circuit cylinders are, though. Gearhead1952 is probably on the right track and it would bleed itself quickly along with everything else during the bleeding process. But with all that said, don't be surprised if you find out that the master and all four wheel cylinders leak or are seized. An empty hydraulic brake system is a breeding ground for rust. If it were me, I'd tear them all down for at least a close inspection and rebuild before I ever poured any fluid in the system.
 
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Old 08-06-2010, 08:39 AM
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Gearhead1952 is probably on the right track and it would bleed itself quickly along with everything else during the bleeding process. But with all that said, don't be surprised if you find out that the master and all four wheel cylinders leak or are seized. An empty hydraulic brake system is a breeding ground for rust. If it were me, I'd tear them all down for at least a close inspection and rebuild before I ever poured any fluid in the system.
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Old 08-06-2010, 09:16 AM
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Every year when I take my trucks out of storage I have to fill and bleed the brake system. I don't know where the fluid goes during storage but once I fill and bleed the system is good for the summer driving season. Never have to add fluid until the following year. I've had this happen on a few othe '48-52 trucks I know of.
 
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Old 08-06-2010, 09:42 AM
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Ilya, just for safety sake I would replace the fluid in the whole system . Brake fluid is corrosive and will eat at the inside of the brake lines and wheeel cylinders . A little work for alot of piece of mind .If you do this process put a clear tube over the bleeder as you release it and run the old fluid into a container as to check the color of said fluid .We have done this with the super late model we ran to check the condition of the fluid in the sytem from break down due to heat , inside line wear , and moisture content .Later , Denny
 
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Old 08-06-2010, 05:50 PM
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Ditto with gearhead1952... If you have the stock master cylinder, then it is just a single chamber design. Just fill it up all the way and start bleeding one cylinder at a time from passenger rear. Make sure to keep an eye on the level as you are bleeding. Then move to driver rear, passenger front, and then finally to the driver front.

FYI, if the fluid is not there, then you have a leak somewhere. Make sure to find where it is leaking. I just did my entire brake system including the lines with exception to the master cylinder. You can get wheel cylinders for about $15/pop. Better than trying to rebuild...
 


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