BRAKE QUESTION 78KC

Yup...sounds like the usual master cylinder seal failure. If the same thing happens with the engine off, you've eliminated the booster as the culprit.

The last time I did one the only hard part was getting the brake lines disconnected from the MC. I recommend brake wrenches to keep from rounding off the fittings.

I would also recommend opening the brake lines at the front calipers and rear wheel cylinders after replacing the MC to get as much old fluid out of the lines as possible, then pouring new fluid in at the top and pumping until it comes out the line at each corner. I've seen master cylinders that didn't last very long due to having junk in the old fluid.

78CobraII said:

The last time I did one the only hard part was getting the brake lines disconnected from the MC. I recommend brake wrenches to keep from rounding off the fittings.

Click to expand...

And don't just turn the fittings off, if their in the least bit stuck you'll wind up twisting the line.

Break the fitting loose, work it back and forth until the fitting turns freely on the tube.

Don't get in a hurry.

I would also recommend opening the brake lines at the front calipers and rear wheel cylinders after replacing the MC to get as much old fluid out of the lines as possible,

Click to expand...

I suggest opening the bleeders before removing the master.

This will drain the master and leave less in the master to drip down the inner fender.

Sure, you can put a rag under it, but you'll need lots of rags.

78CobraII said:

The last time I did one the only hard part was getting the brake lines disconnected from the MC. I recommend brake wrenches to keep from rounding off the fittings.

Click to expand...

Those are called 'Flare nut' wrenches. Sears (Craftsman) and Napa carry nice 3 pc wrench sets at a reasonable price.