How to fix the slack in the 1991 GMC Sierra 4x4 steering

This could be due to a number of causes, as the steering is a chain of linkages or joints:

-steering wheel securing nut loose
-steering shaft universal joint worn or loose
-steering box mountings worn or loose (common)
-tie rod inner ball joints worn or loose (if any)
-tie rod ends worn (most likely)

Jack up the front of the car both sides and secure it with axle stands or some other safe means, have someone hang on to the steering wheel, and waggle each road wheel in and out by gripping it at 9 and 3 o'clock. You should be able to feel the slack. Have another person use a strong flashlight to try to see where this is occurring.

You may need to take it to a front suspension shop as sometimes special tools are needed, and you will need a wheel alignment anyway.

get your gearbox looked at

You need to have someone with a GM factory tech2 scanner go into the computer an change tire size .

Google states: Hold the ateering shaft at the steering box with a wrench or channel locks, have someone get in and turn the wheel. If the wheel turns and the shaft doesn't, then your problem (or at least part of it) is in the shaft between the wheel and the box. If the wheel does not turn then hold the steering box output shaft and do the same thing. If the wheel turns and the arm does not then you have play in the box. This should be adjustable. If there is no play in the box then check the tie rods and ball joints.




Td

check for wheels alignment

It is hard to pin point the problem with out seeing the vehicle in person however from what you have described it sounds like you have a ball joint or a tire rod end broken you probably notice it more as you described when you use the for wheel drive you applying alot of torque and this will cause the symptoms you are having.You should take the truck in to a front end specialty shop this is serious your steering could snap off and brake if you let it go to long.

if your running mud tires have them balanced put mor than likly its frontend parts are worn stabalizer shock or drag link best the u can do is get a friend to set in the truck with is off u look under truck an look at both side to see were slack is or jack fron of truck an shack wheels left wright upp down to find worn parts to

Look under the left side of the vehicle along the frame rail. Follow the cable from the rear wheel toward the front. There should be a device attached to the cable. Tightening the bolt will remove slack from the cable

It is probable that the cable for the speedometer is streached and your MPH reading is incorrect all or most of the time, get a friend to drive behind you at say 55 MPH so you will know the odometer reading ( may prevent speeding ticket )
All metal expands when heated and contracts as it cools. Your cable becomes slack when hot. Stay Safe!

Where does the slack seem to be ? I need more help and info to help? Please do not rate me till I have helped you solve your problem, please do not rate me at all If I can't help you solve your problem. I have had the same problems in the past, tie rod ends, poor alignment, loose tilt wheel mechanism, idler arm, to much clearance on steering gears. etc, I need to understand exactly what your problem is to help.
Merry Christmas