Brake troubleshooting

[CG]

So I don't drive my 68 K20 much, but my nephew likes bombing around in it.
He brought it back a week or so ago and said he thinks he felt or heard a weird clunk and the brakes started acting funny. He told me the pedal goes almost to the floor and its hard to stop. No problem just park it next to the shop and Ill look at it one of these days.

So I drove it today. Pedal goes almost to the floor, hard to stop, and it feels like there are no front brakes at all. When you give it a hard stop the rears lock up.

The truck is a 68 but all the running gear is 72. So before I dig in to this does any of this sound familiar? With the description I gave does anything come to mind?

Mark

[Stocker]

Running gear is from a '72 so it has front discs and a proportioning valve. Check if fluid is coming out of the prop. valve as it may be bad. Or the master cylinder could be bad. open the lines in a few spots to find the problem. This is all assuming the calipers are not getting fluid. There is fluid in the MC, right? Front brakes are probably served by the rear reservoir but check the plumbing to make sure. Check the front brake hoses too. How old are they? They could be collapsed, though probably not both at the same time.

[special-K]

Check master cyl to see if one side is empty... probably is.

Look for the fluid that's been leaked out. Could be anywhere from master cyl, to prop valve, to brake line, to hose, to caliper

[CG]

I haven't checked anything yet. I was concerned when he said it sounded like it was a physical thing that happened. I couldn't think of anything that would make a loud noise or clunk that would happen like that to make the brakes mess up somehow. I believe it has braided lines. Going to be hard to get motivated to dig in to it. I have it parked here at the house, buts its where I cant easily see it anymore. And since I rarely drive it and my nephew is shipping out Tuesday (joined the Navy) its going to be even easier to just let it sit. Talk about lazy, right?

[68panelman]

Yeah, that is pretty sloth like lazy motivation,
I'm thinking it's time to sell...

[OldBlue70C10]

I had an Old Ford one time do almost the exact same thing. It ended up being the brake booster.

[don t. - 72gmc]

Originally Posted by CG

my nephew is shipping out Tuesday (joined the Navy)

Please extend my heart felt Thanks to your nephew
for his service to our country.

Like mentioned, check the master for fluid.
Drive it on a big piece of card board to check for leaks.

Good luck...don t.

[mike16]

yea check the reservoir, the portion of the reservoir closest to the booster or fire wall supports the front system the portion of the reservoir clsest to the front of the vehicle supports the rear. massive fluid loss is easy to notice