1982 Ford F150 brake problem

I just bought this truck. It has disc brakes on the front and drum brakes on the rear. When I brought it home, the brake light was on and the right front brake was dragging. I replaced the front calipers, hoses & pads. I bled out the air, and all looked fine.

Today I was driving it around, and the brake light came on and the brake peddle went spongy. I pumped it a bit and the brake light went off and the peddle felt fine again. I’ve never experienced this before. What do you think? did I just burp a a bit of air out? is my master cylinder wacky? Perhaps I need to flush the brake system out and put in clean brake fluid.

Jim

Replace the master cylinder. Then re-bleed the brakes. I would bleed the how system to get out the old fluid. Also check the rear brakes for leaks. I don’t think you will find any. This sounds like a classic master cylinder failure.

you did ever thing i would have done. know i would check the lines running to the back of the truck and also check the wheel cynders make sure they our dry.

if every thing else checks out good i would think its time for a master cylinder

OK,

I checked the brake lines and they look fine. The rear drums are dry except where a little fluid spilled when I bled them. The fluid in the system is amber in color and a bit milky, so I think new fluid is a good idea. I think I’ll go ahead with a new master cylinder too. What do you recommend I use to flush out the system? I have a compressor, and can use it to blow out the lines. It would be nice to get everything cleaned out real well before I put new fluid in.

Thanks for all the advice. I’m real handy, I just haven’t worked much on autos.

Jim

Just put the new master cylinder on after you bench bleed it and start with rt rear and bleed it then lt rear then rt front then lt front when you get done you will have all the old fluid. Just as you bleed each bleeder make sure clean fluid is coming out.

Thanks!

I followed your instructions and my brakes are working famously!

Jim