Can't get my hydro assist to work

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Dec 19, 2007
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Harrisonburg, VA
85 pickup, I rebuilt the pump and steering gear. I used a surplus center ram, 1.5 x 6 x1. I had a 3/8" hydro line made for the high pressure from pump to box, used 1/4" lines from box to cylinder. I made a larger reservoir and used a cooler. Works great when turning left (extending the rod) but it won't turn right (pulling rod in). The pump i used had the fitting with the 2 small holes for the reducer, i knocked the end of the reducer out with a punch. It is not cavitating. When i turn right it feels like there is no power steering at all, if i give it throttle while turning the wheel, i can feel it let go and then it turns fine. Is it air in the lines, flow, pressure? Any help would be appreciated.
 

gnob

 
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Start by removing the ram entirely.
Block the outs in box.
Check for proper operation.
If correct hook ram back to the lines but not physically attached to the truck.
You should be able to just barely turn the wheel either direction and watch ram work.
 
Joined
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Messages
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Location
Harrisonburg, VA
Start by removing the ram entirely.
Block the outs in box.
Check for proper operation.
If correct hook ram back to the lines but not physically attached to the truck.
You should be able to just barely turn the wheel either direction and watch ram work.
I ran it for a while with the rebuilt gear capped ports and rebuilt pump before adding the ram and it operated fine. If i put the truck on jackstands and the ram unhooked it moves at the same speed as tie rod when turning wheel left. I have to put pressure on the knuckle to get the ram to go right or turn all the way to right stop and it will go in. If i swap the lines on the ram and turn the wheel right the ram extends fine but when i turn left it wont make the ram go in. The pump came off a doner truck 22re, i capped the vacuum ports. The pump internals looked fine but i don't know if i'd know what i was looking at if something was bad.
 

gnob

 
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If you have regular assist without the ram and truck in the floor, the issue is the ram. Sounds like its sticking or has a seal bypassing.
 
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If you have regular assist without the ram and truck in the floor, the issue is the ram. Sounds like its sticking or has a seal bypassing.
It doesn't work right off the ground either. I've also swapped rams and it did the same thing
 

gnob

 
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Alright sounds like some miscommunication here.

With no HA hooked up, you have proper power steering, correct?
 
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Alright sounds like some miscommunication here.

With no HA hooked up, you have proper power steering, correct?
yes, I ran it after i rebuilt the gear and pump, without HA and everything worked fine.

I have swapped out the HP fitting on the pump, stock size and drilled out, no difference. I turned the idle up a little, no effect. Do you think i could have air in the line to that side of the ram? I wheeled it for 3 days like this, would that have been enough to get any air out? I also swapped out the ram with another 1.5 x 6 x .75 ram, same thing, both rams brand new.
 
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gnob

 
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I think one of these is possible.
That one hose is messed up.
Your fitting to the hose or ram is restricted.
Your spool valve in the gearbox is doing something wierd.
 

gnob

 
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Basically the spool valve should open as soon as you start to move the wheels, especially while sitting on the ground.
Sounds like yours is only opening when you max the box out.
Which style box do you have?
 
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Basically the spool valve should open as soon as you start to move the wheels, especially while sitting on the ground.
Sounds like yours is only opening when you max the box out.
Which style box do you have?
i'm using a box of a 91 pickup, no bleeder on top, doesn't have the spanner nut on it where the steering shaft connects. how would i check the spool valve? If i remember correctly, this is the part of the steering gear that is not covered in the FSM. I took it apart and replaced the o-ring in it. Before i loosened the spanner nut inside, i marked the housing, spanner nut and locking nut. I loosened the locking nut, removed it, then the spanner nut. Reassembled with all the match marks lined up. What does the plunger guide do?

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gnob

 
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Centering valve is kind of a detent more than anything.

Still thinking maybe the valve is dirty or the preload on the spanner is wrong.
 
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Centering valve is kind of a detent more than anything.

Still thinking maybe the valve is dirty or the preload on the spanner is wrong.
i used needle nose plyers to get the spanner off, it didn't take much effort. When i screwed it back on i turned it as far as i could with the plyers and my match marks were aligned perfect. could i have assembled something wrong in the valve? I don't remember there being much to it

both the pump and gear came off a parts truck that i have no idea if they worked properly.
 

gnob

 
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Ok. Although ive never been into a double nutted box. The spanner should have been tighter than that.
That shaft requires a small amount of preload.
 

gnob

 
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I recently had a similarly opposite issue.
While working on my truck, i had the ram unhooked from the axle but not the hydraulics.
I zip tied it up to the tie rod so i could move the rig. Well with it just hanging with no attachments, when i first turn the wheels i get nothing, until the ram maxes out and hydro pressure could be directed at the piston. Same symptom in both directions.

Just food for thought.
 
Joined
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Messages
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Ok. Although ive never been into a double nutted box. The spanner should have been tighter than that.
That shaft requires a small amount of preload.
I'm pretty sure i got the preload right, I would not have been able to turn the spanner nut another revolution to my match marks, i couldn't turn it any farther than i did without a bit more leverage.

When i switched the lines on the ram and it worked opposite I think the ram would still extend but wouldn't go in. This should rule out the centering valve becuase that would mean turning the wheel left would extend the ram, so it was still the inward motion of the piston not working. Ill have to switch the lines again to verify. At that point it made me think it was pressure, bc of the 1" rod inside the chamber there was much less surface area for the fluid on the piston, I did't do the calcs but PieRSQ, 1.5" Cylinder with 1" ram, rod is taking a lot of space. But then i swapped it out with a brand new cylinder with smaller rod and still same results. Its really bugging the s*** out of me that i can't get this thing working especially since its my 10yr olds buggy and he can't turn at all when locked and both cases in low.
 
Joined
Dec 19, 2007
Messages
385
Location
Harrisonburg, VA
I recently had a similarly opposite issue.
While working on my truck, i had the ram unhooked from the axle but not the hydraulics.
I zip tied it up to the tie rod so i could move the rig. Well with it just hanging with no attachments, when i first turn the wheels i get nothing, until the ram maxes out and hydro pressure could be directed at the piston. Same symptom in both directions.

Just food for thought.
So you are saying your ram need resistance to work? Mine as well, I have to put pressure on the knuckle to get it moving. What would make the ram not go in until the power steering goes all the way to the stops? Shouldn't the pressure be less at that point. I thought that is what the bypass valve does in the pump once the wheels are at lock?
 

gnob

 
Joined
Aug 2, 2006
Messages
3,207
Location
southern oregon
Just hang your ram. It should move as soon as you move the wheel either way.
Mine wouldn't power the box until the ram maxed and HP was directed to the box piston.
 
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