master cylinder leaks
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Tuned
Joined: May 2015
Posts: 318
Likes: 13
From: Baltimore
master cylinder leaks
Have an 86 F150 with a new master cylinder that leaks at the cover gasket. Put on new gasket but still the same. Should I try bending the hold down spring for more tension ?
New User
Joined: Mar 2017
Posts: 5
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[QUOTE=jackietreehorn;17015929]If you're feeling bold, a modern plastic reservior mc from 87-96 Fords can be bolted on. Took me about 2 hours and hasn't leaked since.
I have an 86 F150 with the OEM metal master brake cylinder. I had planned to do just like you and replace it with the plastic ones used on later years. I pulled one from an 87 F150 and is there anything that I would need to adjust in order to make the swap? So far I'm thinking I may need to adjust the push rod from the booster, was that necessary for your swap or was it just a bolt on swap?
I have an 86 F150 with the OEM metal master brake cylinder. I had planned to do just like you and replace it with the plastic ones used on later years. I pulled one from an 87 F150 and is there anything that I would need to adjust in order to make the swap? So far I'm thinking I may need to adjust the push rod from the booster, was that necessary for your swap or was it just a bolt on swap?
pedant
Joined: Jan 2008
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From: EXTREME southwest CT
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Cargo Master
Joined: Oct 2016
Posts: 2,738
Likes: 217
From: Northern VA
Ford calls it a rear metering valve or something. It's really just a m18x1.5 to 7/16 bushing after its innards are removed.
You could go without it if you were able re-fit the line with a m18 flare nut.
You could go without it if you were able re-fit the line with a m18 flare nut.
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FTE Legend
Joined: Nov 2015
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From: Angier, NC
Lets try Residual Check Valve.
Residual Check Valve Function: Drum Brake System
quote: Many master cylinder's designed for drum brakes incorporate a residual check valve to keep a slight amount of pressure on the system after the brake pedal has been released.
Dave ----
Residual Check Valve Function: Drum Brake System
quote: Many master cylinder's designed for drum brakes incorporate a residual check valve to keep a slight amount of pressure on the system after the brake pedal has been released.
Dave ----
Cargo Master
Joined: Oct 2016
Posts: 2,738
Likes: 217
From: Northern VA
Looks about right except it isn't integral to the MC, more like this one
Ford Master Cylinder Brake Proportioning Pressure Regulator Control Valve OEM | eBay
They seem to serve a different purpose; the PV reduces rear brake pressure whereas the CV prevents air from entering brakes?
Ford Master Cylinder Brake Proportioning Pressure Regulator Control Valve OEM | eBay
They seem to serve a different purpose; the PV reduces rear brake pressure whereas the CV prevents air from entering brakes?
Cargo Master
Joined: Oct 2016
Posts: 2,738
Likes: 217
From: Northern VA
[QUOTE=Squatch90;17017672]
I didn't have to adjust the pushrod but you might. Be sure to get a MC with the same pushrod/ bore diameter and carefully connect the old lines--install them in opposite ports relative to your old MC, front to back--> back to front.
Also, you might need to press the bleeder button on your stock proportioning valve while bleeding to get all the air out.
If you're feeling bold, a modern plastic reservior mc from 87-96 Fords can be bolted on. Took me about 2 hours and hasn't leaked since.
I have an 86 F150 with the OEM metal master brake cylinder. I had planned to do just like you and replace it with the plastic ones used on later years. I pulled one from an 87 F150 and is there anything that I would need to adjust in order to make the swap? So far I'm thinking I may need to adjust the push rod from the booster, was that necessary for your swap or was it just a bolt on swap?
I have an 86 F150 with the OEM metal master brake cylinder. I had planned to do just like you and replace it with the plastic ones used on later years. I pulled one from an 87 F150 and is there anything that I would need to adjust in order to make the swap? So far I'm thinking I may need to adjust the push rod from the booster, was that necessary for your swap or was it just a bolt on swap?
Also, you might need to press the bleeder button on your stock proportioning valve while bleeding to get all the air out.
Cargo Master
Joined: Oct 2016
Posts: 2,738
Likes: 217
From: Northern VA
Originally I bought a new cast iron MC and it began leaking from the piston into the new brake booster about 1 month after installing it. The lid eventually began leaking too. I happened upon a NOS 1990 Ford master cylinder for 25 bucks and went with it. Plus the aluminum and plastic construction makes for a lighter machine! 
Lead Driver
Joined: Nov 2013
Posts: 7,174
Likes: 1,174
Use a file to clean up the top edge of the master cylinder housing. First use an old turkey baster (or similar) to remove as much brake fluid as possible. Stuff some paper towels (damp with brake fluid) in there to catch any debris. Hold the file flat against the casting and work lightly in a crosshatch pattern. You don't need to remove much material, just get rid of any high spots. Remove the paper towels, making sure you get all the debris. Refill the reservoirs.
Inspect the mating surface of the cap, too. If corroded, it may be easier to get a new cap.