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100 Brakes

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RonR

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Folks.

A friend has a 100 that he has been driving for several years after it was restored by the previous owner. My friend was driving home and lost all brakes. There was no loss of brake fluid. The car has synthetic Dot 4 fluid (not silicone).

I suspected that he had a brake lock up and over-heated the brake fluid. However, after the car sitting for days, there was still no brakes, still no loss of brake fluid, and the brake pedal still went to the floor.

He removed the master cylinder and we discovered a small tear in the plunger rubber seal. Rebuilding the master cylinder does not appear to have solved the problem. We cannot get the air out of the lines.

One thought is that air is entering the hydraulic system somewhere. All connections and bleed screws are tight. One would think that if air was entering the system, brake fluid would be leaking out somewhere, but we can not find any evidence of a leak.

It appears that the wheel cylinders were rebuilt (not replaced with new) during the restoration.

Today, we are going to try bleeding the system with a pressure bleeder.
Any thoughts?
Thanks.
 
Remove wheels and watch action of shoes, calipers. If there is a distribution block, check for blockage. Bleed M/C on bench before installing. Check push rod for correct adjustment. Rebuilt cylinders are ok, look for proper installation of cups.
 
RonR said:
Folks.

A friend has a 100 that he has been driving for several years after it was restored by the previous owner. My friend was driving home and lost all brakes. There was no loss of brake fluid. The car has synthetic Dot 4 fluid (not silicone).

I suspected that he had a brake lock up and over-heated the brake fluid. However, after the car sitting for days, there was still no brakes, still no loss of brake fluid, and the brake pedal still went to the floor.

He removed the master cylinder and we discovered a small tear in the plunger rubber seal. Rebuilding the master cylinder does not appear to have solved the problem. We cannot get the air out of the lines.

One thought is that air is entering the hydraulic system somewhere. All connections and bleed screws are tight. One would think that if air was entering the system, brake fluid would be leaking out somewhere, but we can not find any evidence of a leak.

It appears that the wheel cylinders were rebuilt (not replaced with new) during the restoration.

Today, we are going to try bleeding the sysylindertem with a pressure bleeder.
Any thoughts?
Thanks.
Click to expand...

I believe you need to bleed the master cylinder.

Disconnect the brake line from the master cylinder to the line manifold on the right side of the frame. Run a line from the disconnected line back over the engine and into the brake reservoir, keeping this line below the level of the fluid. slowly pump brake pedal until there is no air released into the reservoir.

Kent
 
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