Hi everyone. On my 99 durango the front breaks won't release. Mainly the driver side. With help from a friend, here's everything we've done. changed the caliper thinking it may be bad, blew the lines out, replaced master cylinder, break booster, and the portional valve. None of that worked. I don' know what to check next. 5.9 L with abs 4 wheel antilock

 

Hoses can act like a check valve when they get old.

 

could be the hoses collapsing internally as suggested above,

could also be worn caliper rails, as they wear in the pads tend to leave a ridge on the rails that they slide on (not a greased pin, the rail is part of the knuckle). You can take a grinder or a file to it and smooth this out, grease it up good and you should be good to go.

 

I did notice the rails did have grooves on them. Wasn' sure about using a grinder on them, so I used emery cloth and elbow grease, and smoothed out the grooves and added grease. I haven't checked the hose's. I'l do that next. A friend mentioned maybe a vacuum leaked. What's your thought on that. Something o forgot to mentioned earlier is after the vehical has sat for a few hrs ( no work being done on it ). You are able to spin the caliper.

 

That screams bad hose to me if it releases after a while.

 

based on that last bit, i agree with That_guy, sounds like the hoses are your most likely culprit.

 

When the caliper is locked up open the bleeder and see if it squirts flood and unlocks.
If it does then it's More than likely a bad hose.

 

I'll check the hose and let you know the out come. Thanks to all for the suggestions.

 

I went ahead and replaced the driver side hose, since I went and got the new anyway. Since everything was new, and it was cheap. Due to being late I hadn't checked to see if that work or not. Here's something I hadn' notice or heard before, while I was pumping the break ( while the vehicle was running ) I could hear air. I used my hand and stuck my down by the break peddle. I could hear air every time I pushed the peddle in.

 

the brake booster is vacuum driven, so there will be air movement when you push the brake, its not something i usually notice.