Brake Issue
 

Hello again, 1965 GMC Panel 305E

The truck unfortunately sat for a while (my fault.) When to start it today and when I stepped on the brake, the petal sank to the floor with zero pressure. Pumped it 20x, still nothing. Checked master cylinder, empty. Checked for leaks around wheeles, did not see any. Filled the master cylinder with new brake fluid. Pumped the petal 10-15x. I got some resistance but not quite normal. Waited few minutes, the petal sank to the floor again with no resistance.

If I repeat the process I get some resistance but it goes away after few seconds. When I pump it and the resistance builds, if I hold the petal , it keeps the resistance. It's only when I release the petal that the resistance goes away.

I checked for leaks again around the wheeles and did not see any. I checked the master cylinder again and it was full, no fluid loss.

Any ideas?

Thanks in advance.

Re: Brake Issue
 

You have air in the system, it will have to be bled to remove air. Get a friend to pump the brakes up and start with the wheel furthest from Master, rt rear. Do them in order at least twice.
Since you checked wheel cylinders for leakage, check master to see if it's not leaking, I've had extremely slow weeping on them before.

Re: Brake Issue
 

Thanks, is there any web inks you can point me to? Possibly a video? Thank you

Re: Brake Issue
 

In google, type in: how to bleed brakes

You may also have a worn out master cylinder.

Re: Brake Issue
 

If I wanted to get another master cylinder, is there a part number? Is it still made?

Re: Brake Issue
 

Which style do you have?

https://www.rockauto.com/en/catalog/...+cylinder,1836

Re: Brake Issue
 

My local NAPA store listed the master (dual with clutch and brake) as well as rebuild kits.

Re: Brake Issue
 

He should have the mechanical clutch and use a single reservoir master.
CLICK

Re: Brake Issue
 

Would something like this work to bleed the brakes:


ARES 70923-1-Liter Vacuum Brake Fluid Bleeder - Hanging Hook and Locking Trigger Allows for Hands Free Operation https://www.amazon.com/dp/B07CP1YLDF..._89L7EbSKG5HGP

Re: Brake Issue
 

You really don't need a gadget to bleed the brakes. Just open the valve and have a buddy mash the pedal repeatedly. It only takes a few times until there's no air coming out, then you're good to go. Catch the fluid in a can as it squirts out and re-add it to the system so you don't waste any. Or let it blow out on the ground if you have a lot and don't want grass there for the rest of the season :lol: