I have the same year and model as you, and the same issue. Mine is stiff turning to the left. Changed the PS fluid when I purchased the car last October, with very little difference.
I mentioned the problem to my mechanic when the water pump was being repaired, and he removed some of the PS fluid and replaced it with something called Tranx-X. Seems to have helped a small amount in that the stiffness loosens up quicker, but I still think the rack needs to be replaced. Maybe that will help out for a bit until the money gods decide to come through.

Good luck!

-Ian

'93 945, '90 240.

I had this - stiff to one side - on a 92 and it was the lower steering U-joint - badly frozen & loose.
--
240s: 2 drivers and some parts cars

Rack. I have replaced it on a 90 and a 93 and solved the steering "Morning Sickness" both times. Did not replace the pump. Flushing the steering system can help but replacement is the final answer. Replacing the rack is not too difficult, but it is messy. Try the rack first, if not that then try the pump.

Sometimes a U-joint in the steering column can contribute. Try spraying the lower u-joint with WD40 and see if that helps

Mark

I'll bet that your rack and pump are headed to retirement. The only thought that I have as an interim "fix" might be to go to synthetic ATF in your steering system.

Hi Nel621,

My 90 240DL wagon does the same thing. The pump is a little noisy; bearings wearing out. No leaks anywhere. All new fluid this past year. I suspect the rack is worn and needs replaced; inner tie rods are worn too. Operates smooth after about 10 mins of pumping.

I'm saving up for the pump ($100) and the rack ($200).

Old age caught up with it. Best of success with you and yours.

Brandon in Franklin, TN