I had read this post a couple weeks ago. I always let my Opti 225 warm to 110 on the smartcraft guage before running it but 2 days ago during a Tx prefish, before the last run of the day, the engine wouldn't warm up over 78 in 55 degree water. Eased it back to the ramp and put it on the trailer, pulled the cover and backed it back in on the trailer and ran it for about 5 minutes. Pulled back out and felt both heads, the right bank was much cooler.
Pulled the t-stat on the right head and there was a mesquite thorn stuck in it! The pointed end went right thru the gap in the t-stat but nub end was too big and jammed it in there. This desert lake came up about 50' last spring and there's lots of new brush, trees and cactus disintegrating now and somehow this thorn worked it's way up to the t-stat. Makes me wonder why something big enough to stick in the t-stat would be able to get into the engine?
Thanks for your post Sherm, I had a good idea what was wrong before I even got back to the ramp and it made diagnosis and repair a snap!