Leaky master cylinder. Is this right?

[stomper]

I installed a power brake setup a buddy had removed from his 67. I believe it's from a 71-72 but not sure. When I got it, the booster bracket was mounted 'upside down' so I flipped that over. Now the master cylinder is pointed down slightly. Could this be the reason for my new master cylinder leaking out the front of the cover?

[sick472]

They do point down, at least on my 72. It helps to leave about 1/2" or more between the cover and the fluid level.

Here's an older thread on the topic...

https://67-72chevytrucks.com/vboard/...d.php?t=801452

[samkost]

The Booster and Master do look like what I have on my 72'.
Far from an expert, I have seen other brackets that do tilt forward.
Someone may know that the early year trucks, 1/2 ton or 3/4 ton brackets do tilt down slightly?
sick472 maybe right, overfilled?
If the Master is leaking at the cap, than a new rubber diaphram might be needed?

Good luck.

[stomper]

Originally Posted by samkost

The Booster and Master do look like what I have on my 72'.
Far from an expert, I have seen other brackets that do tilt forward.
Someone may know that the early year trucks, 1/2 ton or 3/4 ton brackets do tilt down slightly?
sick472 maybe right, overfilled?
If the Master is leaking at the cap, than a new rubber diaphram might be needed?

Good luck.

Forgot to mention, it's a new master. Already rusty from leaking a few days.

[toolboxchev]

I always touch the cast surface of the master with a near new file to see how flat the surface really is. Put some paper towels in there first.

You have to seat the rubber gasket every time you open it. After putting the clip over the top I move the upper part of the master around to get this done. If there is any rust showing on the rubber scrub it with a Scotchbrite and Dawn to get it removed. This helps the rubber create a seal.

Farm tricks rule sometimes.

[my67c20]

Chased the same leaking cover issue on mine for days. Tried dressing the surface, shaping the cover to actually seal, bending the retainers and nothing worked. Finally wandered around an old area with junkers sitting there and snagged a cover from a Cadillac and boom no more leaks. I think the retainers are to flexible and same with the cover as they flex too much and prevent an all around seal.

[stomper]

Originally Posted by my67c20

Chased the same leaking cover issue on mine for days. Tried dressing the surface, shaping the cover to actually seal, bending the retainers and nothing worked. Finally wandered around an old area with junkers sitting there and snagged a cover from a Cadillac and boom no more leaks. I think the retainers are to flexible and same with the cover as they flex too much and prevent an all around seal.

Hmmmm. Maybe I should try the cover off the old one after I swap in the new seal. Good put.

[toolboxchev]

Some will weep a bit. I took a good look at my Napa brand new unit and the top has a small indentation to let excess fluid directly out the top.

Go figure.

[stomper]

I put the old lid on the new MC with the new gasket and that stopped it. The old wire bail clamp things were noticeably tighter on the old MC. I tried swapping those out but it was apparently the distance from the top of the MC to the wire bail clamp pivot location is shorter on the new unit body. Probably from machining the top surface on the rebuilt unit?