[AlanJohnson]

This is a problem I had last year on my coach. I want to record what happened here in case it will help anyone else.

My power steering started getting jerky a couple years ago. It finally got to a point where I had no power assist. And yes, it becomes a beast without power steering.

I can usually fix most things myself. I replaced the hydraulic pump, and spent quite a bit of time talking to mechanics at Newell. After replacing a few more items (including the new hydraulic pump) I finally threw in the towel decided to try to make it to Miami (from Dallas) and let the experts fix it.

It took Newell mechanics 5 man-days (1 guy for 3 days, and another for 2) to finally figure the problem out. (They removed and replaced almost everything two or three times, and even removed the steering gear). 

The problem was in the hydraulic fan motor. Unfortunately it was not documented anywhere that there is something in the fan motor that controls the power steering.  No one thought they were connected... and the fan appeared to be running properly. But in the end the fan was either restricting fluid going to the steering gear, or diverting it.  The fan motor was changed and I was back on the road. 

I was feeling rather dumb that I couldn't figure the problem out. The only redeeming thing I got out of the whole experience was the satisfaction that it took 5 days for professional mechanics to figure out the problem.   

My engine is an S60.

[Richard]

Thank you for posting Alan.

Tom and I were aware that another owner Paul Tracy experienced a similar failure. And it took new hyd pump, new control solenoids, and new steering gear box before it was identified as a faulty fan motor. To the best of my understanding the hydrualic system feeds both the steering gear box and the fan with any pressure regulating device regulating the flow to either . If the fan motor internals allow excess flow through the fan motor, all of the hyd pressure is consumed just pumping fluid through the fan and back to the reservoir.

My comments are hindsight, but for others reading this thread, here is an idea I think would be fairly easy to try if this problem is suspected. Unscrew the hyd return line from the fan motor and cap it. The return to the reservoir would have to be capped also. If the steering problem goes away then voila! the problem is the fan motor. Of course you couldn't run like this for very long, but it's far less effort and money than replacing the hyd pump or steering gear box.

[360]

Don't have a loss of power steering entirely but in low speed situations such as jockeying into parking spot it seems to be partially losing power steering. Best way to explain it is kind of like a pulsing sensation when you're turning like it's losing power steering, getting it, loosing it, etc. as you're turning. Assuming this is not a normal thing and wondering if what I'm describing is this issue with the hydraulic fan motor?

[RussWhite]

Brad,

Consider this as a possible explanation. And, yes, my coach does that too!

In a parking situation the wheels may not be rotating much, if at all, and you are trying to change their direction. There is a lot of weight on those steer tires and a lot of contact area with the pavement. I think the hydraulic pressure you are producing turning the steering wheel causes the high pressure relief valve to open and you get that pulsing sensation. I think it will go away when you are able to rotate the steer tires while turning them. Russ

[Richard]

Both Newells I have owned had the same behavior at close to zero speed.

[encantotom]

lets go 3 for 3 with me

tom

[360]

Problem solved. All I've driven that was halfway comparable were heavy trucks and there it was not an issue that I can remember, but it's also been many years.

[bestgenman]

An experience with no power steering caused me to become more familiar with the system.   The hydraulic feed to the steering box (on 567) is a #8 AII braided hose, it must have dropped down at some point and rubbed on the cooling system valve block feeding the aqua-hot and dash heat.  The supply hose to the steering box is fed from the fan control block.  A small hole rubbed into the line caused the fluid to leave the system while trying to back up to a trailer.  A considerable amount of steering input involved when in tight quarters.  When the wheels are not rotating, the 365 ground patch is about one square foot and 9,000 lbs  ground pressure, making it nearly humanly impossible to turn without assist even rolling.  
Those of you having the same supply line configuration might want to inspect for rubbing.  I shudder to think what would have happened at high speeds.

[johnkosir]

I lost power steering for a few seconds and then it came back 5 miles later I noticed a line of oil on the grass when I pulled in to my campsite, looked like it was coming from the distribution block, while cleaning up the distribution block with a rag so I could see where the oil was coming from I noticed the solenoid for high fan moving, when I tightened the solenoid the oil leak stopped. I replaced the O ring it is a standard ORB 10 O ring. Added 3 gallons of synthetic transmission fluid too top the tank up. 4 trips and 600 miles later I lost power steering again while driving my motorhome back home from being in Florida for the winter, pulled in to a rest area in Ocala at 9:00 at night went to the back and checked the oil , the tank was full, I figured I would look at it in the morning. When I went back in the morning I found 2 gallons of ATF on the ground leaking from the OHLA. I remembered a post where Richard had bypassed the oil going to the OHLA and filled it with grease. I planned to plug the pipe coming out of the motor, put a grease zerk  fitting in the OHLA fill it with grease and try to drive 1400 miles home with no power steering. I called Richard to see what he thought of my idea and he explained to me that I could not plug the drain on the motor it had to go to the reservoir, when I told Richard I was in Ocala he said I was not that far away from him and he would like to come up and see me ( I think he meant he would like to increase the odds of my repair being a success, one definition of happiness is being broke down in your Newell and having Richard show up) The hose for the return line broke when I was bending it and I had to go and have a new one made. We installed the  3/8 JIC male flare to 1/4"pipe in the pipe to the OHLA put the 1/4"  zerk in the fitting, put the 3/8 to 1/2 JIC adapter on the fitting on the motor hooked the hose up filled the OHLA with high temp grease, started the motor and filled the OHLA with grease again, Richard went home for dinner, and I cleaned up hooked up the trailer and started the trip back home, made it about 1000 miles with no oil leak, then started leaking bad lost 1 1/2 gallons in 50 miles, filled the OHLA with grease again, slowed down to 50 mph from 61 mph (shifts into 6th at 61 so that is where I try to drive) to try and reduce the amount of time the high fan is on I tow a loaded 30' stacker my motor works hard, first time I was happy to hit hard rain which reduced the amount of time fan was on, oil leak really slowed down probably 1/2 gallon in last 400 miles home, if I had too do it again I would stop every 200 miles and fill the OHLA with grease,
When I got home I called Newell to ask how to troubleshoot it, I was told to put a pressure gauge in the small line that goes to the steering gear box and there should be 2400 psi I had 0 psi called Newell again and was told to call George at Hydraquip in Tulsa he could help me troubleshoot it. George suggested that I replace the 2 pressure regulators on the distribution block they were not that expensive and that would eliminate them from being the problem, when I went to a local hydraulic supplier was told 10 week for 1 and 20 for the other one, So I made a fitting so I could check the release pressure on the relief valves one was 2000 psi and the other was 2400 psi what they were suppose to be. I put the relief valves back in and checked the pressure again and got 0 psi  I capped the line to the steering box and got 2000 psi, I called George back and told him that I had 0 psi in line and 2000 psi when I caped the line he said he knew nothing about steering boxes but it look like I had a problem in my steering box. I looked at ZF steering box manual that Jeff posted on the site (thank you Jeff) and noticed that it had a relief valve in it. I called Newell to see if it was possible to remove to relief valve with the steering box in the coach so I could make a plug for it to see if that was the problem. Spent quite a bit of time talking to Gerry and realized that I was checking pressure wrong Newell has a ball valve in series with there gauge and you only get pressure when you close the valve . Gerry said they have seen fan motors cause the power steering not to work, so I capped the lines to fan motor and checked pressure same thing. Gerry called me back and said he went and looked at a coach and talked to other mechanics and you can get the relief valve out but it is evil. ( you have to love Newell service)  I though about what Gerry said and went back and capped the lines to the fan motor again and tried the steering wheel I had power steering you only have pressure in the line when you turn the steering wheel. George said the distribution block  was fan priority so it turns the power steering off to keep the fan running. Do not understand why I did not have power steering when the fan was off. Took the motor apart there is damage on the valve body I am trying to find parts

[Richard]

I owe John a huge apology. Old age and failing memory are coming at an inconvenient time. I had completely forgotten about this post when John called with his problem.

This is why I pound on the use of the search engine.

Thanks John for taking the time to post your ordeal.

I want to add one thing to John’s commentary that I learned second hand from Jeff King. On the ZF steerable tag coaches there is a hydraulic circuit independent of the hyd pump that provides considerable force to center the rear tags, and inadvertently the front steer tires. That centering force is easily overcome if the hyd pump system is working, but the coach would be extremely difficult to drive in John’s case. John commented to me in off line conversations that the coach was a beast to turn even when rolling. I am commenting just to capture this situation in the thread.