Different application and Ive never had a water pump apart on a 235, but I had an s-10 and I chased that darn thing all over trying to figure out why it had the most erratic over heating issues, never the same thing twice.
After going through everything several times I pulled the water pump. The impeller had a small hairling crack in the center. So it would sometimes overheat and it would loosen up just enough to spin on the shaft and not circulate water. Sometimes it worked sometimes it didnt.
Just an idea.
Jeff
