No brake hydraulics

Randy Gulli

Randy Gulli

Red X
Hi,
It's been a few years since I've been active on the forum. I have a 75 X 1/9 and it has been garaged since 2015. Prior to storing it, I had the brake system completely redone. New master cylinder, new discs, pads and calipers. The braking system was perfect.
Now after 4 years in storage, I started the car and it runs perfectly but when I went to back out, the brake pedal went to the floor. No hydraulics at all. The brake fluid is full. The pedal springs back.
Where should I begin to look? Mind you, I am not a mechanic but I have done some simpler tasks on the car in 41 years..
Thanks in advance for any advice

Randy
 
Have you tried pumping the pedal with your hand to try and build up pressure. Try it slowly like giving CPR to sick friend. If nothing is wrong it should come back but also check for puddles.

Does the clutch feel normal?
 
Sitting unused even for relatively short periods seems to lead to similar hydraulic failures. Unfortunately it very well may be possible the master cylinder has failed again despite being new when parked. However it is certainly worth a try to flush and bleed the fluid before tackling the (somewhat laborsome) task of removing the master cylinder.
 
Cratecruncher said:
Have you tried pumping the pedal with your hand to try and build up pressure. Try it slowly like giving CPR to sick friend. If nothing is wrong it should come back but also check for puddles.

Does the clutch feel normal?
Click to expand...

Yes, the clutch is fine...
I pumped for a while but I'll give it another try..
 
Or there was an air bubble left behind that has migrated to the MC?

I would start by trying to bleed the front brakes, this is simple to do and doesn’t require being a mechanic.

If you can get fluid out of the front brakes then it is possible the MC is still fine.
 
I suspect the master cylinder has failed or more accurately the seal. My 1300 had the master cylinder replaced 5 years ago before I had the car but the car had stood for some time and when in use the pedal progressively went soft then failed when I attempted to bleed it. I have a suspicion the current master cylinders available are poor and don’t tolerate being left standing. I would also pressure bleed not pump the pedal as this will almost guarantee a seal failure.
 
NEG, I guess I should have explained why I suggested pumping the master brake cylinder. Sometimes the cup seals will stop making good contact with the bore. A few pumps can exercise and expand the seals to start functioning as a seal again and restore pressure. It works best on cars that have been sitting for long periods which were parked with good brakes. Before predicting mechanical doom and gloom I like to suggest easy fixes first. Since Randy, our thread starter, told us the brakes were just rebuilt and operating fine four years ago it seemed a great candidate for a pump up. Also, if any air is in the line it will gradually compress the air pockets allowing pressure to restore gradually, albeit temporarily. That feedback would indicate the system just needs a bleed. It might also suggest a kinked reservoir hose as you discovered digging into yours. I also asked Randy to check for any leaks because if that master is dry the fluid had to go somewhere. I suppose it could have slowly dripped out and soaked into the carpet or something. I let a car sit for a while and had the pedal shoot to the floor. It turned out a hard line had rusted though and the brakes were peeing on the garage floor. In forty years of bolt twisting I have never heard of pumping a pedal leading to a "guaranteed seal failure" as you put it. But if a wonky master is going to fail I'd rather it happen in my garage than a congested intersection 40 miles from home. I try to be brief when posting on forums but this warranted a bit more than usual. Sorry for the wall of text xweb.
 
I appreciate the input by everyone. I did try pumping the brakes to see if pressure would build up and that was before my post. The floor is dry inside and under the car. The reservoir is full as the day I parked the car.
If bleeding the front brakes isn't too difficult, I'm going to try that first. Sounds like there is either air in the line or the MC is bad.

The day after the brake work was done, I had no brake pedal. Posters from this forum had me crack a screw at a joint ( I forget what it is called) in the back behind the slave cylinder behind the rear tire. There was air trapped there and after that the brakes were fine. I should also mention that I started the car and drove it once a week for several years and the brakes were fine so time appears to be the enemy....
 
Randy Gulli said:
crack a screw at a joint ( I forget what it is called) in the back behind the slave cylinder behind the rear tire. There was air trapped there
Click to expand...
That is basically what "bleeding the brakes" is. It is easier with two people; one to pump the pedal and the other to open and close that bleeder screw. Maybe look for some YouTube videos on how it is done for a better idea. Definitely worth a try before going further.
 
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