Help me understand Hydroboost/brake issue
Posted: Sun Feb 09, 2020 12:13 pm
Truck is a 1989 K1500 GMT 400.
Last summer I completed a brake upgrade to a 2005ish Suburban type four wheel disc system. After system was bled properly- worked very well.
- hydroboost was an unused unit off of fleabay with a larger diameter mount so I removed the existing HB/MC and installed a MC off of a 2005 K2500HD with the proper dia mount. Things were good. Stored the truck over winter and started it a couple times, went for a short run yesterday and there is a problem.
- brake pedal has sunk, brakes lights stay on, brakes a super hard- but I am still able to stop. I am asking because I came accross a Corvette comment that the HB doesn't like storage and may unstick after some usage, and I don't understand why something works then doesn't.
- There were some changes:
- changed the pump due to excessive steering effort on new gear- steering effort is acceptable now. This was the first step in troubleshooting the steering and condemning box.
- changed return HB line, the res is a divorced unit with can above it, from an Atro I thing- old return went right to lower res, changed return to go tp upper res- for nothing other to get a little circulation of oil. I don't see a restriction here.
Last summer I completed a brake upgrade to a 2005ish Suburban type four wheel disc system. After system was bled properly- worked very well.
- hydroboost was an unused unit off of fleabay with a larger diameter mount so I removed the existing HB/MC and installed a MC off of a 2005 K2500HD with the proper dia mount. Things were good. Stored the truck over winter and started it a couple times, went for a short run yesterday and there is a problem.
- brake pedal has sunk, brakes lights stay on, brakes a super hard- but I am still able to stop. I am asking because I came accross a Corvette comment that the HB doesn't like storage and may unstick after some usage, and I don't understand why something works then doesn't.
- There were some changes:
- changed the pump due to excessive steering effort on new gear- steering effort is acceptable now. This was the first step in troubleshooting the steering and condemning box.
- changed return HB line, the res is a divorced unit with can above it, from an Atro I thing- old return went right to lower res, changed return to go tp upper res- for nothing other to get a little circulation of oil. I don't see a restriction here.