Temp problems???

[olemissalum]

This weekend noticed that all day Saturday 502 EFI would only get to 140 degrees, and stayed at 130 mostly. This started two weeks ago when I bumped into a sandbar back home with engine idling. I shut down immediately and watched temps closely to see if I had ingested some sand but instead of overheating now runs 30 degrees cooler??? I guess the thermostat has stuck partially open, should I just replace it or could the gage not be reading right. Any pointers????

[MOP]

I would pull the thermostat it may have given up the ghost. A little grit may have gotten through. I hit a bar with one of my boats, when I drained the block for winter quite a bit of sand came out, it can get through.