1997 gmc 5500 topkick

[deshooter]

Hello and please help. I have this old Asplundh truck will it has only 63000 miles on it. The brakes are hydraulic....blah. The growling sound it makes when u press the pedal and the brakes arent fully charged will not stop. U sually we hold the pedal while starting and release when growling stops this charges the brakes. Other day growling never stopped all lights and buzzers came on. Let off brake and it stopped but all lights stayed on. Then whenever you touch the brake pedal it growls again. I put a new master cylinder on it and all I got was a stiffer pedal with same symptoms. I really need some help on this one Ive had a string of bad luck with equipment recently and really need to fix this one myself $$$$$$$$ Thanks in advance for all insight you have to offer. :msp_biggrin:

 

[ROPECLIMBER]

Ck the powersteering fluid sounds like a hydrobooster sucking air how is the powersteering while braking, if it is a hydrobooster they are around 500 but could just be low on fluid or have air in it make sure the power stering is topped of and then purge by turning both ways to lock severel times while hitting brakes intermittantly, thats if it is a hydroboost system good luck,
Paul