1995 Mercury 175 XRi
Usually change impeller every 2-3 years. It is just cheap insurance.
I changed it this winter and also changed the 2 thermostats, knowing they had never been touched. They looked okay, but first time out, it had the highest water pressure I've seen on this engine.
Also, I was able to unplug my speedo pickup while I had the lower unit off. It was clogged with mud and looked like it had hit a stump and folded the metal over. a quick hit with a 1/16" drill bit and it opeed the hole back up. Now it is reading within 1 mph of GPS!
