Dennis,
What I am about to tell you will probably be repeated by others....
Old brake line hoses often deteriorate from the inside out. They may look OK
but, they begin to fail on the inside. The interior passage begins to deform
and act like a check valve. When you apply the brakes you cause several
hundred pounds of hydraulic pressure to go from the master cylinder to the
brake cylinders. This much pressure can find its way through a nearly blocked
interior passage. Unfortunately, this is not true in the reverse. When you
release the peddle there is very little pressure going in the other
direction. That is, from the brake cylinders backward to the master cylinder.
In fact, you want them to bleed back to essentially "0" PSIG.
What happens is that the pressure in the brake cylinder never quite all
bleeds back to the master cylinder where it is supposed to. The brakes drag.
More pumping of the peddle just makes it worse. Finally, the pressure never
bleeds back much at all and you burn the pads and / or shoes. I had this
happen on my '73 MGB a few years ago and on my son's '76 Midget last year.
The same thing can happen with the clutch hydraulic system too. You can check
those hoses by taking them loose at each end and try to blow through them. I
bet you won't be able to do it on at least one of them. Replace ALL of those
hoses then see if the problem doesn't go away. Do it quickly, too before
major brake damage occures and check to make sure it hasn't happened already.
By the way, I recommend using at least DOT 4 brake fluid for better hydraulic
system life. It's not much more expensive than DOT 3. Silicone is even better
but, you've got to remove ALL of the old fluid and it's a lot more expensive,
at least in the short run.
R. Johnson - Dallas
'90 Maine Coon
'79 Midget
'76 Midget
''73 MGB
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