Power Steering oddity

1990 XJ, 4.0, AW4.

About a year ago, I replaced the power steering pump with a remanufactured unit I found in the junkyard. I also replaced the return hose and added a filter in-line. At that time I filled with Valvoline power steering fluid and replaced the steering intermediate shaft. Later, I replaced the column. The high pressure line was replaced in 2015.

The unit has performed quietly and flawlessly until mid August. At the time I was at six weeks of 20 mile, mostly highway commute. The engine typically cruises at 2500 RPMs, with occasional 4000 RPM blasts to pull a hill or pass traffic.

The problem, the power randomly cuts out. I first noticed while getting off the highway, the steering wheel is hard to turn. Lightly jerking the wheel back and forth confirms the tires do respond to minimal input. Then, the power returns. It can cut out in the start of a turn, then as I crank on the wheel (hard), it comes back halfway through the turn. That part makes the problem a little spooky. The past few weeks, the problem has manifested itself at lower RPMs, and the pump does whine a little.

I have checked the fluid level, no leaks, no foam or other signs of cavitation. The fluid is still clear.

I am guessing the pump has a bypass that is sticking open. I plan to replace the filter, which will drain some of the fluid.

Should I be looking for a different type of fluid to refill the system?

What other things can cause this problem?

TIA

I'm guessing here, but there's probably a spool valve in the steering box that's sticking. As you said, next step would be to replace the filter (or temporarily remove it as a test), and try an additive to see if it would free things up...

This may sound dumb but check your belt it may be a little loose

If axle u-joints are worn out they can cause the steering to bind.

On my 97 XJ the power steering pump would go limp pulling in and out of parking spaces. I never really had any problems on the road. That doesn't mean it's not possible.

If I had to guess I'd say I'd say the box is on it's way out or bad u joints. But kinda hard to say. Power steering pressure gauge would be only way to really know for sure. You can jack the front up, turn the wheels to lock and spin the tires by hand to check for a siezed u joint real quick. If it gets hard to turn or locks up you'll know it.

I've been using the Valvoline power steering fluid for a long time. Still rocking the original pump.

Thanks for the responses!

The Jeep has been parked at work since the end of September. When I get it home again, I'll check the belt.

Most power steering fluid these days comes with stop leak. Maybe that's what the previous owner ran in that pump? Reman from junkyard usually means they just paint it. They dont rebuild it. May be gummed up

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Time to revive this thread! I found this video from last year.

I installed the current power steering pump and a different filter after making this discovery:



I'll have more pictures later.

At this point, I think the spool valve sticking might be the culprit. The last time this problem manifested itself was after a 4000 RPM blast uphill.

There are other factors, I'll cover those when I update.