Hey all. I got a 1986 F250 6.9 4x4 C6 Automatic. Coming home from work today and came to the last stop light and the truck wouldn't stop too easily. Luckily I wasn't going to fast. The brake pedal is super hard like its trying to be a leg press machine. and even with forcing it down it doesn't stop the truck that well.

It also wouldn't shift up to 2nd when i started to go again. It will manually shift from 1>2>3. But not automatically. I've run into the shifting problem before after some work on the motor I forgot to reconnect the vacuum lines to the vrv and I pulled over super angry and thinking "What now?!" only to realize my mistake.

I did pull over real quick and just quickly assess for any leaks and fluid levels and just a quick once over of what vacuum lines I could see on the side of the road. it all looked ok and no brake fluid leaks I could see.

Does this sound like a vacuum issue? If so can someone help point me to a starting place? I'm no expert mechanic but I've always managed. I'm moving from Eastern North Carolina to Western New York on the 15th and ol' Big Al here was supposed to be the work horse for that.

As always all help is very appreciated.
Chris.

 

Go to autozone. Rent their vacuum pump tester. Pull the vacuum line, test it. Should be about 20psi suction. (i read anywhere form 19-25psi is good)

I did this about 4 days ago. Replaced the pump, all good now.

Full refund on the tester by the way.

You will also need to rent a pulley remover from autozone or O'Reillys. Full refund if returned within their allotted time.

My breaks got hard. Even harder on a double pump.

 

This is what my old pump was pulling:



Under 5psi. No good.

Make sure that the vacuum pump tester comes with this white piece. You will need it to adapt the clear tube to the vacuum line. Mine didn't have one so I went to autozone and purchased it for like $2.

 

X-2. I've had the same problem, First check pump vacuum. If that's ok just go down the line until you find where you don't have vacuum. I was lucky, mine was a rotted hose.

 

Thanks for the replies. Yesterday stayed busy when I got home from work. Took the S-10 to work today. I'll have to get on this after work and I'll post what I find. Cheers

 

i've had several failed vacuum pumps on mine over the years. you either have a major leak or a bad pump. they're really simple to replace once you have the right pulley tool

 

Sorry for the late response. Hurricane Matthew sure threw some wrenches in the plans of a smooth move. Tested the old pump and I was pulling a whopping 0 psi. Got a new pump and a new pulley. Definitely need the pulley tool because even with it can be a p.i.t.a.

New pump pulls 25 psi and the brakes and the transmission work great again. Thanks for all the help guys.
Chris.