Power steering problem

[Declaration Day]

Hey guys, I have a 1993 Toyota Camry that has developed a power steering problem.  Specifically, it cuts in and out intermittently, usually in 1/2 second increments. 

The car otherwise steers fine.  The belt that drives the pump is not slipping.  The system is not leaking, not low on fluid, nor does it have the usual whine that indicates air in the system.

So is the power steering pump failing, or is something possibly wrong with the steering unit?

I've replaced a few power steering pumps, but so far only because they've sprung a leak from corrosion.  I've never had one fail mechanically, and don't know if they fail suddenly or slowly.

I'm usually one of the guys answering this type of question, but I'm the one in need of help this time.  Thanks in advance!

[crt360]

Possibly a vacuum valve problem?

[Parker Dean]

Difficult to say without feeling what it's doing myself, but the most likely culprit is the rack. Sometimes the internal valving sticks, or there's a wear issue on the seals and it applies pressure to both sides at the same time. Internally. That last version is virtually impossible to steer when it's happening. Either condition can come and go without warning.

Pumps usually get weak over time causing increased effort at low engine speeds. Most of the time people don't notice because it's gradual, although rapid steering inputs at low speeds where you get about a quarter turn of the wheel and then the steering stiffens is a giveaway to a weak pump. . One way to check is to turn the wheel with the engine idling and then again with the engine at about 2000 rpm. There shouldn't be any significant difference.

One thing to keep in mind is that some of these older systems use a cruder version of variable assist where it's either High or Low assist switched by a solenoid valve based on inputs to the ECM. Later versions have been moving to a continuously variable assist where the solenoid is duty-cycled to vary the pressure bleed instead of an on-off type operation. I mention this because if it feels like it's just switching between High and Low assist you may "only" have an electrical issue.

[richyoung]

98% sure its your power steering rack.  Replace it or the car, although Lucas transmission additive may buy you a few months time.

[Declaration Day]

Thanks for the advice, I'm going to fix the car.  I can do just about any repair myself, so I only have the cost of the part to worry about.