The GMC CCKW

Do not forget to check your CCKW Steering Gear at regular intervals, as the seal at the sector shaft is prone to leaks because of age and proximity to the red hot exhaust pipe. 60 years takes a toll. (mine seeps and there are oil spots on the PTO shaft, when I get ambitious I will instal a NOS steering gear to eliminate the leak)

If your Steering Gear leaks, do not try to cure it by adding Chassis Grease, as it will cavitate and the upper bearings along with the balls in the Guides may not get good lubrication.
Joel

I have put chassis grease in all of mine for 25 years now. Only one went bad. The Bomb Truck was full of water when I got it because it was an open cab. 50k+ miles with no problem in the cargo truck.

Cavatation is generally associated with water propellers turning too fast in the water and creating such suction that it basically boils the water due to low pressure.

Cavitation also is associated with all fluids and chassis grease is a fluid. (I was also supervisor of a laboratory that tested asphalt and petroleum products) amongst the many duties I had when I had to work for a living.

I may have stretched the definition of cavitation, but the heavy viscosity of CG may not allow it to free flow into all area where the lube is needed. GO is the best lube for the steering gear. 562,000 CCKWs couldn't have been wrong.

When I started my apprenticeship in the 60s we had to check the steering box on every oil change. Not many vehicles then, especially trucks, had power steering. We took out the filler plug plus one other bolt to let the air out. We used a needle to add chassis grease and then topped up the box with outboard motor lower unit gear oil. I still do the same today and in all those years have never had a problem. Removing the other bolt to let the air out may be the secret I don't know. We used this procedure on our stock cars for years also. They would get a lot more heat (header proximity) and abuse than a truck ever would, admittedly they only turned left.
Cheers,
Barry