This question is for a friend...

He has a 95 f-250 (6.9L front discs, rear drums). His brake pedal is very mushy and when pumped up, the pedal bottoms out after about 8 or ten seconds of constantly applied pressure. They pump back up just fine but then fade again.

Our first thought was a leaking wheel cylinder- but all four are bone dry. Second thought was air in a line- but we bled all the lines and no change. None of the lines or hoses are bad or leaking. We have checked the system over and haven't found anything to cause this. I'm sure its probably something simple that we are overlooking, so I seek the wisdom of the board. Any ideas?

Thanks,
Nate

1964 F-100 Custom Cab 292 V-8 3 spd
1964 F-100 292 V-8 3 spd
1990 F-150 5.8L
http://www.geocities.com/revnate64/Revnate.html

 

Bad Master cylinder?

 

Oh YEAH!!! Definately MASTER CYLINDER.

When you replace it, make sure you clean the fluid reservoir out. There's bound to be dirt and crud in the bottom. Use brake cleaner, spray inside liberally and shake. Flush remnants out and set aside to dry.

Make sure hands and tools are squeaky clean. USE NEW (BREAK THE SEAL JUST BEFORE POURING!) brake fluid. Bleed and fill.

 

Thanks! I'll pass your advice on to him.

Nate

1964 F-100 Custom Cab 292 V-8 3 spd
1964 F-100 292 V-8 3 spd
1990 F-150 5.8L
http://www.geocities.com/revnate64/Revnate.html

 

I've changed a FEW of these and offer this advice. Change the power booster too if he can afford it. My experience is that the booster is going to go out within a couple months of changing the master. You can buy it as an entire unit, it's easier to install, and you will only be under the hood once instead of twice. This is of course assuming he has power brakes.

 

Definately Master Cylinder