There isn't a drain plug...at least I've never seen a steering gear box on the AD half ton trucks with one. One way to drain the box is to remove the worm gear retaining cap and bearing and let what is in there either run or drip out. But it may not do that easily. You'll find all sorts of things could have been used as a lubricant in there...and you will get lots of different ideas about what you should use. Hopefully for you the original lubricant will still be there. GM was vague about what that lubricant was. People are going to tell you to use everything from chassis grease to a 50/50 mix of heavy gear oil and chassis grease to corn head to straight STP (which probably isn't a bad idea, actually) to very heavy gear oil. Whatever you use it should not get thick and channel in cold weather...which in Minnesota you will naturally get. If you're going to go to the trouble of draining what is in there and cleaning it all out to replace the lubricant, I don't know...I think I might be tempted to pull the sector shaft cover and shaft, clean that up and make a new gasket (cut one out of something thin but tough like a manila folder) and replace the sector shaft seal while you have the shaft out. The seal isn't expensive, isn't hard to replace and the one you get today will be better than what is in there now. If you do this, be sure to clean the sector shaft well where it meets that seal and be sure to use some gasket sealer (I use Permatex 2 non-hardening) on all the threads and gaskets. These have a way of seeping if you don't seal them. Good luck.
Jon
Last edited by Jon G; 07/06/2015 4:05 PM.
