push on brakes front calipers won't back off keep getting tighter and tighter on 2001 GMC Sierra 2500 HD

they get so tight i have to stop and open the zerks to releave presure, thats normal driving, but comming to a stop i but it in nutrial and use brakes they seem to not lock up so soon

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1 answer 2 comments
possible contamination in brk fluid or hydraboost could be going bad, i had that issue on a ford f350 diesel
so maybe because of the rust in brake line issue, it's blocking some port?might have to flush brake lines out? how would you test the hydraboost?
its very diff. to do most likely the valving is going bad internally,flush the brk sysyem completely with alot of new fluid 1st and see if that helps.don't forget to flush master cyl really good