brake fluid pressure

[Mark D]

Had an issue arise over the weekend in the process of shifting the convertible from the body shop over to the storage unit in waiting for the new interior to be installed.  Had a starting problem that was turned out to be glazed points and a weak coil, and noticed the brake lights were on as it was being worked on. The car also has a very hard brake pedal and the brakes seem to be dragging.  All four corners got new brakes and cylinders last summer, although the car has not been driven more than 100 miles since.  One of my buddies thinks the fluid in the reservoir expanded and that was triggering the pressure switch for the lights.  A good triple stomp on the brake pedal offered no remedy to the condition.  I rebuilt the MC myself, but am thinking that the internal passage for the brake fluid return may be clogged.  Anyone have suggestions as to a remedy before I pull the MC and buy a replacement?

 

 

[kencombs]

First thing I'd check would be to make sure the return port is being uncovered when the pedal returns.  To little free play between linkage and piston could block that.

[Don Coatney]

Make sure the pictured hole in your master cylinder is not plugged. The fill cap for the master cylinder is vented so no pressure can build up.

 

[Jerry Roberts]

Also some of the members have had the inside of a rubber brake hose collapse and block the return of brake fluid . 

[Young Ed]

Did you mess with the pedal freeplay? Lack of pedal freeplay could cause what you described. 

[Mark D]

8 hours ago, Young Ed said:

Did you mess with the pedal freeplay? Lack of pedal freeplay could cause what you described. 

 

No never touched the free play, but all things point to this being the problem. The shop that did the brakes for me last year had the car for the non-start issue and asked me if I have done anything to the brakes as well. The car literally has been in dead storage except for one recent run to the auto body shop. I’m guessing the 10 miles I drove it was enough to create the issue. Also guessing the free play was not re-adjusted after four corners were done by my mechanic.

[Don Coatney]

Is your pedal all the way to the top after upping it a few times?

[greg g]

To reprise, for proper brake system performance.  Assure pedal travel free play, ( at least 1 1/2 inch) assure return port is not blocked, assure reservoir cap vent is open to atmosphere, assure reservoir is not overfilled, check condition of front rubber brake hoses.  Assure brakes are properly adjusted and properly bled.

[Mark D]

1 hour ago, Don Coatney said:

Is your pedal all the way to the top after upping it a few times?

 

Yes, very hard pedal after only a couple pumps. Feels as if the brakes are dragging. Think you guys are spot on with the pedal free play. My guess is my mechanic did not adjust free play after installing and resetting concentric.

[Don Coatney]

That means the small bleed back hole I posted about is not clear. Adjust the free pay and you should be cured.