My 1999 XK8 power steering has a problem. When I turn the steering wheel, it is initially hard to turn then gets easier, for a bit, then becomes harder, then easier.

Here is some history
- After changing the octopus hose last fall, I had a P0171 lean bank A fault. It was time to park the car for the winter so I didn't try to find the vacuum leak.
-There were NO problems with the steering when I parked the car.
- During the winter, the battery went completely dead several times. (I would recharge the battery to start the car now and again, but didn't try driving it.)
- A couple months ago when I started the car to move it so I could resolve the P0171 problem, I noticed that the steering was heavy and cycled between hard and easy to turn.
- Because of the steering issue I let the car sit another 2 months.
- This past weekend I found/fixed the vacuum leak and then started trying to figure out the steering problem.

I searched the forum trying to find others with my exact problem.
Based on what I read on the forum I have done the following.
- There are no groaning noises or any noises out of the ordinary when the steering is turned and there are no leaks in the system.
Jacked up the front wheels so they could move freely and turned the steering rack back and forth - Symptoms did not change.
- Removed fuse #12. Turned steering wheel back and forth. Symptoms did not change.
- Put the fuse back in and tested again. Symptoms did not change.
- Checked the electrical connector on the top of the rack. Connector appears to be good.
- Decided to flush the power steering fluid, (Swapped out a full quart of fluid.) Symptoms changed slightly - Same problem, but steering input is a little lighter, but Steering still cycles between harder and easier.
- Drove the car at various speeds - Symptoms remain, across all range of speeds.

Ideas concerning what to look at next would be appreciated.
- Could the control module cause this?

 

On jacks and with the engine not running, does the steering exhibit the same behavior? You need to rule out mechanical issues.

 

Had a similar problem. Defective lower ball joint replacement cleared the problem. There was movement in the bad ball joint, check yours?

John

 

Steering exhibits the same behavior without running engine and both wheels in the air.

Refined symptom: The steering wheel is heavy to turn, heaviest at about 45 degrees each direction, then becomes easy to turn at about 90 degrees each direction,

With wheels in the air and centered straight forward, cannot feel any play in the steering rod ends or clunking/play where the steering rod arms go into the rack.

 

+1 on checking mechanical causes first.

A few thoughts on fault finding.
1. Check PS pump. Might be simple as the Belt might be loose on the pulley
2. Check for leaks as the metal/rubber lines are known to leak at the crimp junctions
3. Look closely at the rack for leaks including the gators. As this is a new problem, are they filling with PS fluid? If so, then you have leaks in the internal seals. O ring Kits are available to refresh PS racks. Not really DIY able so you’ll need a specialist garage.

 

A few thoughts on fault finding.
Belt is fine, checked that : 1. Check PS pump. Might be simple as the Belt might be loose on the pulley
As stated in the original post, No leaks. All lines appear to be in good condition 2. Check for leaks as the metal/rubber lines are known to leak at the crimp junctions
No fluid as far as I could tell in the gators/Boots. Rack and lines are amazingly clean. 3. Look closely at the rack for leaks including the gators. As this is a new problem, are they filling with PS fluid? If so, then you have leaks in the internal seals. O ring Kits are available to refresh PS racks. Not really DIY able so you’ll need a specialist garage

I am trying to think what can happen to a power steering system that was working well without issues before the car sat for 5 months. Engine was started 3 times and warmed up, but not driven during that period of time. Before each start, the battery was completely discharged and had to be recharged and jumped to start the car. Fluid reservoir was at the proper level before I flushed it out with new fluid.

mhminnich asked if the symptoms were there without the engine running, and they are, so does this imply a mechanical rack problem rather than asteering pump issue, or pressure or electrical?

 

Tijoe,

Think you're probably right in that it's a mechanical rack issue as the variable resistance is there without the car running. Maybe a problem at the steering column spline to rack junction. Only way to check is to remove the rack. Fixing the rack is a specialist job though.

 

Tijoe,

Found this in one of Jag's guides for general info on the PAS system. Might help you.



The internal rotary control valve may be the culprit in your case.

 

I would double check the u-joints at the bottom of the steering column, along with the spline fittings for anything loose. Maybe have a helper turn the wheel and visually inspect what those u-joints looks like while turning. I believe one joint is visible from inside the car, the other from under the car.

Best of luck, keep us posted.

PS: In the off chance this is an issue with the u-joints, you might want to just not drive the car for a bit until you can confirm steering is safe.

 

This morning I took a more methodical approach to inspecting the power steering system.

Jacked up the front of the car and removed the wheels.
Closely inspected tie rod ends - Looks good.
Took a real close look at the gators/boots for any cracks or signs that the rack is leaking and the rack mounting to sub-frame, . - Looks good
Rotated the steering wheel without engine running both directions trying to get a better feel for the amount and change in effort to crank the rack back and forth
Started the engine and did the same thing. Interesting to note that the effort without the wheels on the car is exactly the same with or without the engine running. (Pump is becoming suspect.)
Had the wife come out and turn the steering wheel back and forth without engine running while I crawled under the car. I could hear a squishing/gurgle in the rack when it is first rotated in either direction. (almost like the sound of bubbles or fluid being pushed around.)
Had her start the engine and turn the steering wheel back and forth. She said it was taking the same amount of effort to turn as no engine running. Engine is too noisy to hear any sounds in the steering rack..
Looked over the steering universal joint and other rotating parts, all looks good.

Next questions:
What other parts could be bad that would prevent the system from pressurizing? Is there a pressure switch or relief valve in the pump that could be the problem?
If the pump is bad, that doesn't explain the "hard to easy" rotation of the steering wheel. (Unless fluid in the rack is going under pressure then releasing?)

 

Try disconnecting both tie rods next, then do the engine off test. That will isolate it to the rack and or column u joint.