Brakes got hard to press, heard brake booster vacum pump was bad, thumb tested it had little suction but couldn't test it to see if it was to specs.Replaced it got about another inch of play out of pedal but still no brakes, whats next? 95 f250 psd w/standard tranny

 

Trace your vacuum lines. Especially the little ones on the passenger side of the engine bay that control your HVAC. They're plastic and love to crumble into dust.

 

You might have leaks in other areas of the vacuum system causing it to not be working properly. Your brake booster could also be leaking.

Welcome to FTE!!! Glad you're here!

 

I'll check them, what all do they run? (Vacuum lines) I noticed yesterday my vent control for mu heater wasn't working but all my others were working, unrelated issue?and how can I test for leaks in the power brake booster. I did have to fill my brake resavor when it happend

 

In a gas engine, it is usually quiet enough running that you could hear the leak if there is one in the vacuum booster. As for what else it runs, everything in the climate control system in the truck except for the fan obviously. I would pull the vacuum line off the booster, plug it, and start your truck and see if that allows all the climate controls in the truck to now work. That should narrow it down for you. BTW, it's not unheard of that your new vacuum pump could be bad right out of the box.

 

Like said above, its usually that little plastic white vac line on the passenger side. The hood hinge will rub it and break it. It will run into a harness and make it almost impossible to replace. You'll just have to repair it.

 

Just so we're all on the same page -- it was the PUMP (the belt-driven one) that you replaced, and NOT the BOOSTER (on the firewall), correct? Did you do the thumb test after replacing the pump? Where did you do this test? Right on the vacuum line going into the booster?

There's also that little check valve on the booster, that the vacuum line connects to. If that's failed, you'll have no boost.

 

here is mine...


But my brakes work fine. this hose controls the recurc door. So if there is no difference between Max AC and normal AC... this is the problem.

I am betting on the one way valve on the booster...

Richard

 

^^^^ +1; HVAC uses so little of the vacuum capacity of the pump, that you could probably have a wide open HVAC vacuum line and still have at least adequate brake boost.

 

I think I want to switch to hydroboost and the electric vacuum pump that the SD's have when my pump dies. I have an eye out for parts.

Richard

 

It was the belt driven pump, no didn't check it after I replaced it I'll check all this after work how much suction should it be getting? Thanks you all appreciate it

 

The vaccume pump should pull a minimum of 17 inches, if you have a gauge.

 

Thanks I'll try and locate a gauge , look for vacuum leaks didn't find any thanks for all the help

 

Is there a way to test or check the one way valve?

 

Pull it off and blow through it.... air should only flow one way... might want to clean it a bit first...

Richard