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In search of...Hydroboost
- Thread starter Suprdave1
- Start date
NVW
Well-Known Member
Make and Model of truck would help.
FellowTraveler
Well-Known Member
Sounds like an early retro fit of the hydroboost II setup with an internal accumulator/piston which was discontinued back in 83/84 some parts houses may have replacement parts if not then its going with a unit from a GMT400 GM truck or newer would be an option.
smokymtn65
Well-Known Member
I would contact Pirate-Jack
Found a spring and retainer. Tried bleeding the power steering and it’s really foamy. Let it sit a day, no foam tried bleeding again and foamy! Also, my brake pedal is actually being sucked to the floor!,! I can pull it up and it sucks right back down. Checked hoses for proper routing and according to the diagram from CPP it is correct. Outlet next to the return line goes to the gearbox, outlet on the opposite side comes from the pump. Kinda frustrating
Pic of line setup? Esp of booster.
You should have a 3rd "return" line from hydroboost to tank of PS pump? Any restrictions to that true return line and it would prevent the brakes from releasing. This includes filters. (Filters go on return from box to pump.) If you plumbed the HB return to the steering box that could do it...
IMO you got it backwards. Pressure from pump to Hydro-booster then from booster pressure to gearbox. So Pump, Hydrobooster, then steering box.
You should have a 3rd "return" line from hydroboost to tank of PS pump? Any restrictions to that true return line and it would prevent the brakes from releasing. This includes filters. (Filters go on return from box to pump.) If you plumbed the HB return to the steering box that could do it...
IMO you got it backwards. Pressure from pump to Hydro-booster then from booster pressure to gearbox. So Pump, Hydrobooster, then steering box.
That’s how mine is plumbed pump to booster booster to gearbox. T in return line
FellowTraveler
Well-Known Member
A "Y" fitting is far better IMO....
Our trucks have 2 return fittings on the pump tank. Not saying it's wrong what you have. Again any restriction in the return can muck up the works where the spool valve in the hydro booster will not release. If you are satisfied with that then we:
1) Purge the air from the system some more.
2) Check the Master Cylinder is actually returning.
3) Find another hydrobooster as this one is perhaps defective.
On #2 this is engine off blead air out of brake system and check for a firm pedal. If the pushrod length between the MC and booster is too short or long ... maybe cause problems.
On some systems a failing nitrogen charged accumulator can leak into the hydraulic system and cause foaming. The pressure of this failure sometimes blows the PS cap off on Dodge Cummins for example.
- Staff
- #11
What did the hydro-boost come off of? There's several different styles of hydroboost. I know most go with the small one from an Astro van.
FellowTraveler
Well-Known Member
OK! The unit is the one used in the GMT400 and newer truck applications w/external accumulator.
Have you turned the wheels lock to lock several times or more to bleed air from the system? This is important!
Past this, the main piston maybe scratched from foreign material like sand maybe small metal fragment and allowing air to be sucked into unit. Spool valve sticking etc........
From here I suggest buying the full kit pirate jack sells however you need specialized tools for some of the seals so you don't damage them......if perhaps you need another unit justchevytrucksdotcom.
Yes I tried yesterday and going to try again later today. Why is the pedal sucked to the floor¯\_(ツ)_/¯ I can pull it up, but it goes right back down
FellowTraveler
Well-Known Member
"Dead accumulator maybe this old brian forgets exactly what causes that situation" I've always rebuilt for leaking main piston seals and changing out the main piston however; just one spec of dirt can cause nightmares jamming the smallest parts inside there.
FellowTraveler
Well-Known Member
Many people seal the weep hole/slot under the unit where it bolts to the master and put a filtered vet to keep out sand and dirt. From here an inline hydrollic filter and return filter (s) too.........
Does that site just sell rebuild kits or do they sell remanufactured hydroboost pumps.? I'm asking cuz mine is completely shot.. no power brakes at all and I have to add power steering fluid every other day.. checked all the local junk yards and none of them have one they say mine have to come off a 95 - 2000 truck. Honestly not sure if that's right or not ...just know it would be nice to have good brakes again..
Where is the leak?
Have you run the system "dry"? If you ran the system dry: Flush the cooler, replace everything else. Yes: PS Pump, Hydro-Boost unit, hoses, and steering box. Because you will never be able to flush all the metal debris out of those parts from running it dry.
@RockAutoLLC RA isn't bad prices.
Leaking out from between the hydroboost and the master cylinder.. it never ran dry. I noticed it when the brakes was started going bad and Ive been keeping an eye on the power steering fluid to make sure it doesn't go empty