Nice weather this weekend for the first time since Christmas, so traded out the series 3 daily for the XJ-S on Friday. Aside from an occasional idle hunting, it ran well all weekend. This afternoon, however, I noticed it's a little sluggish to return to center after turning the wheel right or left.

Tires are all at 37 psi with plenty of tread left on them. Car drives straight without drifting right or left, corners flat, is wicked responsive and sticks to the road like it's on rails.

Rack was replaced within 10k miles, steering pump and hoses replaced within 5k miles. No leaking power steering fluid.

Any ideas?

Thanks in advance,
Rhett

 

Stiff/worn/binding ball joints and/or tie rods?

Not enough positive caster in the alignment settings?

Cheers
DD

 

Further to Doug's point: assuming fluid levels are OK and fluid not thickening up for temp reasons, you could jack up the front and, engine off, see if there is any resistance you can feel while turning full lock to full lock.
If there is, and you have a ball join separator, disconnect one of the steering rack to steering arm balljoints, then the other, then both, and see which side or if the rack itself, has some resistance to swivelling.
Greg

 

My ideas:


1. Too much PSI in the tires. OK for flat out top speed, o'wise, bumpy as ....
Relation to issue, none.


2. I'm with Doug as to caster.


Carl

 

I am only with this if the owner has adjusted the caster, or worked on (eg) new balljoints, and the problem he describes has appeared afterwards. I got the impression this fault had appeared on its own after a bit of a winter layoff. Obviously I could be wrong!

 

Correct. I drove the car last on Christmas eve, before this weekend. It was fine until suddenly, during the drive, it wasn't.

Drove it to dry storage this morning, it's determined that it's not just that the wheel doesn't return to center: There is a bit less power assist when turning right or left but it's worse turning left. There's a spot about 11 o'clock to about 10 o'clock (turning left) where the power assist drops significantly and then, from 9 o'clock to the lock, the power assist resumes, somewhat.

The pump was a rebuilt unit, installed less than 5k miles ago. The rack was replaced when we got the car about 10k miles ago but it's may have been a rebuilt unit as well (I didn't source parts then the way I do now).

I haven't had anything done to the ball joints or made any adjustments to the front end for some time.

 

Hi Rhett

Not much more than a Shot in the dark but wondering if the Steering Rack needs bleeding, might have some air in the Piston, which 'could' give you a flat spot.

But as I'm not an expert, others will advise.

 

That means one or more of:
Pump rebuild not working correctly
Rebuilt rack not working correctly
Steering rack balljoint/s failing.
POSSIBLE constriction/blockage in the high pressure hose

Still worth changing the PS fluid, just in case. After that, in your position I would still do the tests I mentioned, after that if nothing conclusive, start with the pump and inspect the hoses, maybe a seal has become displaced etc, and it is the cheapest thing to replace first.
Greg

 

It's very unlikely, but tighten the belt on the pump before replacing anything. Nothing lost.

 

System was bled and given new fluid but the problem persists. It doesn't feel like I'm losing power assist as I turn the wheel but like it's encountering increasing resistance until the resistance goes away like going over a bulge. Once over "the bulge", the wheel requires additional force to go back past the "bulge" to return to 12 o'clock. I've tried to illustrate it using the clock face attached. Does that make sense and, if so, does it indicate anything specific?


Trying to document the resistance in the steering on my XJS

 

Well, the general consensus is that there's a mechanical (as opposed to hydraulic) problem with the steering rack. Which is annoying because that was one of the first things I had replaced on the car only 10k miles ago. But it was with one of the first 3 mechanics I ultimately fired on my way to finding the shop I enjoy working with now. Maybe this one will do the trick.

 

Okay, new rack installed. The binding while turning is gone but the car is still lazy returning to zero after a certain point, from either a left or right turn.

Pump is functioning correctly.
Ball joints look good.
Hoses look good.
No PS fluid leaking.

Anything else we should/could try?

Thanks in advance,
Rhett

 

Toe adjustment.

 

Had a 3rd steering rack installed and the problem is gone. Finally.