Hydroboost

G

grr456

Club Member
Hydroboost - Update

Anyone know anything about hydroboost systems? I have on on my Chevelle and the pedal is rock hard and I can't seem to get them to work correctly...

Yes:
The connections are correct
Brand new power steering pump - Original GM Style pump
2 separate return lines Not Teed - (1) from Rack & (1) from hydroboost
Hydroboost is brand new - Not remanufactured
Went thru bleeding instructions multiple times

Anyone want to come over and help me figure this out? Free beer, or whatever....

Thanks........Gary
 
Last edited:
What brand/part number is the hydroboost unit?

Does the pedal effort change at all when you turn the steering wheel? Does the steering wheel have smooth assist through the full range of motion?

Im thinking maybe the PS pump pressure relief valve isnt allowing enough pressure to get to the booster for proper assist. Do you have a pressure gauge?
 
mustangmike6996 said:
What brand/part number is the hydroboost unit?

Does the pedal effort change at all when you turn the steering wheel? Does the steering wheel have smooth assist through the full range of motion?

Im thinking maybe the PS pump pressure relief valve isnt allowing enough pressure to get to the booster for proper assist. Do you have a pressure gauge?
Click to expand...

http://www.hydratechbraking.com/GM_A_Body.html

Rock hard all of the time. Nope, no pressure gage.......
 
Some other things to look at:

Plugged return hose/cooler
Belt slipping
Binding linkage
Engine idle speed too low

Ill see what PSI my transmission gauge goes to or if it will work for troubleshooting.
 
mustangmike6996 said:
Some other things to look at:

Plugged return hose/cooler - Brand New - Clean
Belt slipping - Nope
Binding linkage - Nope
Engine idle speed too low - Kicked it up...

Ill see what PSI my transmission gauge goes to or if it will work for troubleshooting.
Click to expand...

Added Response
 
Hmm, Im working through a generic troubleshooting tree. Most of the results are pointing to a defective hydroboost unit, assuming the pump is fine. Since you have steering assist the pump should be ok.

Have you driven the car or are these results stationary? Im wondering if the brakes are locked up, which could be incorrect pushrod length.

Does your brake system have a residual pressure valve(s) to keep pressure on the rear drums?
 
do you have the feed line for the hydroboost pre or post the power steering pressure sensor?
 
Beigg said:
do you have the feed line for the hydroboost pre or post the power steering pressure sensor?
Click to expand...

Don't know where a sensor is, but the hydroboost is fed high pressure first, then to the rack then one return from the rack and one return from the hydroboost.

Gary
 
Air is likely trapped in the system or it lacks a check valve. If you identify the sensor and you're able to remove the pressure sensor easily, unscrew it and observe it noting how the fluid escapes. Should be steady stream no air bubbles.
 
Beigg said:
Air is likely trapped in the system or it lacks a check valve. If you identify the sensor and you're able to remove the pressure sensor easily, unscrew it and observe it noting how the fluid escapes. Should be steady stream no air bubbles.
Click to expand...

Don't know where the check valve would be, because I don't have one inline and the instructions don't call for one.

grr
 
If bleeding the system to rid of any trapped air doesn't yield positive results then I'd be inclined to suspect a faulty component. Power steering pump , hydroboost, or gearbox
 
I've noticed 1600-2100 psi for H-boost systems being the norm for high/feed and 500-800 for low/return.

It's almost impossible to cross the lines during install, but double check to make sure the high and low lines are correctly plumbed for the system.
 
Changed the pressure valve, now the rears are totally locked up - Removed the pushrod completely from the rear master so that isn't it...Time for a little more investigation......
 
Update - I got the entire brake thing working now. I dicked around with the bypass valves internal to the powersteering pump and that was the initial no brake problem I had. After increasing the pressure, the rears were locking up and I couldn't get them released without bleeding the system. Seems I had a defective line lock I am going to use for my emergency brake. I removed it and now everything seems to be working...Never ending tale of woe...

Gary
 
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