93900 Isuzu NPR box truck arrived today for a steering concern. The driver reported that the steering was, "hard to turn." While I couldn't detect any increased effort issues, I was able to verify that the truck wandered quite a bit on my road test.

The first step in the diagnosis was to check the front suspension and steering linkage for any worn out parts. Everything looked and felt good in the front end.

With the steering linkage in good shape, that points to the steering gear box as the culprit. After many years and miles, the gear box innards can become worn which will manifest itself in the form of free play in the steering wheel. This results in the truck "wandering" while driving.

There is an adjustment nut on top of the gear box. I've heard two schools of thought over my 20 years in the business regarding adjustments. The first is that provisions for adjustment are there for a reason, and a small amount of adjustment is allowed. But the second is that if the box needs adjustment, it's already worn out and needs to be replaced. With the customer complaining of the steering wheel being, "hard to turn," I decided to replace the gear box.

I've learned that the word "Isuzu" comes with its own inherent set of problems regarding parts availability. The easiest way to ensure that I would be getting the correct replacement gear box was to take a picture of the tag on the old one. The part number is on the bottom of the tag.