hey guys on my 72 f100 work truck i have to pump the brakes about 4 or 5 times to get pressure up to stop.i drove it today and it scared the crap out of me.i was wondering what this may be.the master cylinder looks kinda wet along with the fittings on the side everything else is dry and it is loosing brake fluid but never drips that ive noticed all the calipers ary dry as well could the master cylinder be letting air in the lines?before i started working for this company the truck was neglected.im thinking the master cylinder what do you guys think?

 

If you are replacing fluid it is leaking somewhere, or it got low and you got air in the line.

Did you check the inside of your tires to see if there was any wet looking places on them?

Reman master cylinders aren't very expensive neither are wheel cylinders. Have you upgraded to power discs? Might be a good time to put that in the hopper.

Keep check on the fluid level and don't be afraid to do a check pump until you get the issue resolved.


John

 

Check the inside of firewall and see if it's damp. Alot of times it will seep inside the truck(where rod comes thru). Sounds like it's got alot of air in the lines, plus the fact the master cylinder may be bad.

I would definitely start looking hard for the problem, as driving around like that is NOT safe.

 

It seems to me I heard something about how a master cylinder can leak into the power brake booster, assuming you have one. You might not. In any event, has anyone ever heard of such a thing?
Hartski

 

Read the post before yours.


John

 

I did. There's no mention of a power brake booster in any of the threads. But that doesn't mean there isn't one.
Hartski

 

If this 1972 F100 has calipers, then disc brakes have been swapped in.

 

If you are loosing fluid with no apparent leak, it is probably leaking out the back of the master into the booster. Remove the master and see if there is fluid in the booster. If not, some times it takes a while for a wheel cylinder leak to show itself on the outside of the drum. Take off the drums and inspect the cylinders. Have fun,
Mike

 

hold steady pressure on the brake pedal, if it slowly sinks to the floor you have a bad plunger in the master or a leak somewhere. did you bleed them good?