Power assist steering.

[MadMC63]

Dear Sirs,
I have browsed through the help section and not found what I'm looking for.
I have a 1971 D100 with power assist steering that will not function. All hoses are new and in the correct location. Control valve has been rebuilt twice and the ram once. The power steering pump is new. It is at least as hard to turn in either direction as manual if not harder. I am now into this setup for about $1200.00 and are truly bewildered and disenchanted to say the least. I feel that I have overlooked something simple and obvious but are blind to it. Any feed back will be appreciated. I really do need some advise here.

[powerwagon54]

double check hose locations

[MadMC63]

I installed the hoses one at a time. When things didn't work I purposely switched the right and left turn hose connections which resulted in no turn possible. I have been using illustration page 19-5 as a guide. Now, not to seem naïve, what exactly happens if I swap the pressure and return hoses if they are already in the correct location? Fearfully I'm picturing hydraulic fluid dripping off the ceiling, truck and me.

[MadMC63]

O.K. I swapped the pressure and return line connections on the control valve. With the truck in the air I noticed a slight resistance ( this was new) while turning the steering wheel from lock to lock. With the truck on the ground there is no discernible difference. No hoses exploded or blew off and no leaks. I'm truly at a loss. When I originally purchased the system I received the entire system as one piece minus the power steering pump. The gentleman removed all of it without breaking any other connection. That is how I initially installed it. In my mind I keep coming back to the control valve. Its as if it isn't being actuated. When it originally didn't work I had to control valve professionally rebuilt. When that didn't work I had the hydraulic ram rebuilt. When that didn't work I went back to the control valve, disassembled it and inspected all that had been done. With nothing obviously discernible I took it to a different company and had them go thru it a second time. When this didn't work I removed all of the hydraulic hoses and had them replaced which I hate because they butchered most of the attaching straps.

[PwrWgnDrvr]

Just because the pump is new does not mean it is functioning. Have u put a gauge on it to verify u actually have the specified pressure?

[MadMC63]

Don't have a pressure gauge. I'm not saying it's impossible but highly unlikely that three pumps in a row would be bad. What no one understands is that I have been working off and on for about a year now trying to make this work. I really am bumfuzzled.

[Hobcobble]

Don't have a pressure gauge. I'm not saying it's impossible but highly unlikely that three pumps in a row would be bad. What no one understands is that I have been working off and on for about a year now trying to make this work. I really am bumfuzzled.

Terry mentioned "specified" pressure. Perhaps the pumps you've been working with don't have
the required/specified amount of pressure?
John
viewtopic.php?f=20&t=39670&start=20

[pismopowerwagon]

Is it possible to install control valve center part backwards? Just trying to understand your issue that must be frustrating.

[MadMC63]

I did notice when I had the control valve apart it would go in either way. That's been in the back of my mind this whole time. The hydraulic shop was the first to disassemble the unit. If they installed it backward holy cow would I be upset.
Any idea what symptoms that particular error would cause?

[PwrWgnDrvr]

....Any idea what symptoms that particular error would cause?

Ya, it might not operate correctly...

[PwrWgnDrvr]

If the valve piston is not machined symmetrically, then it matters which way it is assembled. Lots of stuff goes together 2 ways, but only one is correct, ie: engine pistons in a cylinder, piston rings, engine bearing caps, brake shoes, the list is endless. As in all things, one needs to know WTF they're doing. Just ask the guys that built the space shuttles. They blew up 2 out of 4.

[Rawbert]

Maybe try testing each part individually and narrow down your problem. Or if your sure it's the control valve, maybe you can find a unmolested original. I feel your pain. I just removed my complete assist system due to leaking and not working correctly. In my opinion the power assist doesn't help enough for all the headaches. Good luck.

[MadMC63]

Just reading through the service manual again and noticed on the 100 and 200 models the spool can go either way. Based on what I'm seeing and reading the spool is unidirectional. The larger D models have a different style of spool/ valve body that only installs one way. So that's out. Looks like this is a fire and money just became water. I'm sure I can find that pressure gauge setup at Advance for fifteen to twenty dollars.

[pismopowerwagon]

The two inner fittings are more spread out than the outer's ones, so in other words the two tight together fittings are towards the wheel.

One other thought is they put an o-ring in wrong groove on piston

[PwrWgnDrvr]

This system is a really simple hydraulic circuit. U need to verify pressures at all points in the system in order to isolate where the defect is. IE, u either have pressure at the ram (when turning), or u don't. If there is pressure, and it doesn't assist the turn, then the ram seals are bad and fluid is passing thru it. There should be NO fluid THRU the ram.
Can u post a pic of the control valve and indicate which hoses are connected to what?

[MadMC63]

Front to back, Hoses closest to you are the front. Left to right, left is the front of the vehicle and right the rear, looking at the control valve from the drivers side hose connections are as follows:
Right turn line: Left front.
Left turn line: Right front.
Return line from valve to pump: Left rear.
Pressure line from pump to control valve: Right rear.
On the ram the left turn hose is attached closest to the axle and the right turn farthest.

[PwrWgnDrvr]

What is "illustration page 19-5"? I'm studying the FSM and don't see a hose diagram in section 19. Page 19-5 is the manual gear box.
Based on the control valve diagram in section 19 page 22, it appears your left and right hoses are reversed. But its hard to tell for sure.

U could try disconnecting the ram from the axle and see if it goes in and out when u turn the wheel back and forth. (wheels off the ground, engine running). Before testing it with engine on, hold steering wheel full left or right and try to pull it in and out by hand. If u can move it, the ram piston seal is bad.

U simply need to check the system one step at a time to see where the anomaly is.

[soopernaut]

What is "illustration page 19-5"? I'm studying the FSM and don't see a hose diagram in section 19. Page 19-5 is the manual gear box.

63-68 Parts book

[zkemp82]

Not trying to be sarcastic or anything, and if you decide to ditch your system I'd be interested in your hoses, but did you make sure you bled all of the air out of the system?

[MadMC63]

Oh, most definitely. I've been in this system so many times not only is there no air in the system but the fluid is so clear you can see through it without any difficulty. I'm going to have to get a pressure gauge and get the pressure readings. I know the system should have a neutral pressure of between 24 and 85 PSI from the pump to the valve. The valve amplifies the pressure to the ram so... what should the pressure from the valve to the cylinder be?