72 gmc k15 4x4...HELP lost brakes

[bubs72gmc]

Hello all,

I was driving home from Virginia beach last weekend and lost all brakes, had to pump them to get stopped, wife did not like that ride home at all!

I do have power brakes with brand new pads on the front and decent drums on the rear.

My dad and I bleed all the brakes and still nothing. If I pump the brakes a few times then I get some brakes, but I'm lost now.

Anyone have any suggestion as to where to look next, how to check the master cylinder and/or the brake booster?
Posted via Mobile Device

[Wrenchbender Ret]

It is most likely the master cyl. I would pull the rear drums first & make sure something hasn't come loose like a wheel cyl. rod not in the brake shoe. If the rear brakes are OK & adjusted up replace the master cyl. Remans are not expensive. Bench bleed it before you put it on. Pull the vacuum check valve out of the booster & make sure there is no brake fluid in it.

[Ol Blue K20]

most likely the master cyl if none of the wheels are wet
Posted via Mobile Device

[ole dollor]

i agree with everyone else, you have a bad master cly.

[GASoline71]

Is it a stock engine? Or do you have a snotty cam in it with a lot of overlap?

Gary

[bubs72gmc]

Thanks for all the replies,

I took the check valve out to check the vacuum (was good) then I did have a little bit of brake fluid come out of the hole on the booster. Wiped it off and it never showed again.

I have a basic 350 with bolt ons no internals. So no cam issues.

I will try the master cylinder, as nothing is wet.

I will post my results later this week, thanks guys!
Posted via Mobile Device