engine tempature on a I/O

Two weeks ago I got into shallow water and sturred up some sand for a couple minutes. This last weekend I noticed my engine temp was running about 60-80 degrees cooler. Normal temp is about 180 and current temp is 100-120. I have a 2004 I/O 4.3 liter mercrusier alpha one. Is it possible to have some sand stuck in the termastat causing it to stick open? Where and how can I ckeck the temp sensor and guage? Thanks

Sounds like you could have sand holding t-stat open. To be safe just replace it they are pretty cheap. Easy way to check temp gauge is to remove wire from sender and ground it. When grounded the temp gauge should go all the way hot.

Oh yeah dont forget to check your impeller as well. If you havent changed it yet now would be a good time since it is 2-3 years old anyway.