What would cause the brakes on my wife's truck to be stiff and not hold?

 

Sorry 04 f150 5.4

 

I had a similar issue years ago and it turned out to be the brake booster. I'm not sure how to diagnose it but mine actually showed a brake warning light on the dash as if the parking brake was on. Just my opinion. Hopefully others will chime in.

 

I had to pull the intake manifold off yesterday and pulled a line off but just fixed it and now hard brakes

 

Brake booster runs off vacuum, if the line you removed was a vacuum line, that will probably be your issue

 

I reattached the line

 

Should I pull vacuum line and release the vacuum?

 

pull the black hose off the brake booster and see if there is vacuum when motor running....... hard brake normally means bad booster, or lack of vacuum to booster. Since you just removed that line, I would check it for connection and pluggage.

 

Correct me if I'm but if there is a vacuum leak going to brake booster, wouldn't truck miss and idle rough?

 

I have no vacuum to the hose running into booster

 

well, you got that narrowed down....... take the hose off the motor end and see what is going on.... YES, if vacuum is completely lost, the motor should run rough... You also need vacuum to get the heater controls to blow air to the floor and dash.. no vacuum will blow only on defrost.. ........ I would pull several hoses off one at a time and check... check PCV hose to valve cover for vacuum from motor also.

 

I couldn't get ahold of any rubber vacuum hose Sunday so I used 3/8" id air hose instead, would you think that would be a problem? I'm trying to avoid pulling intake manifold for a third time

 

My opinion would be yes. The air line hose would be too soft and collapse.

 

This air hose has a plastic core in it

 

Then it may be okay. I was picturing just a rubber hose without a core. For your sake I hope it works out.