The temperature guage on the dashboard of my 1999 Suburban 5.7 almost always points 1/4 around the guage at about 160 degrees. The guage never points to the half way point which would be closer to 200 degrees. The ECT on my OBDII scanner reads 195 degrees (when fully warmed up). I believe the thermostat and radiator cap are working correctly. I replaced the temperature guage sender recently, and nothing changed in the guage reading. I also tested the sender by putting it in hot water with a thermometer and the thermometer reading matched the guage on the dashboard.
So for some reason, it appears the engine temperature flowing out of the head near the thermostat (where the ECT sender is located) is correctly around 195 degrees, but the engine temperature in the block (where the guage sender is located) is about 160 degrees. I'm wondering why this is so. I'm thinking my cooling fan may always be running, providing too much fan air to the engine. When the engine is off, it takes a decent amount of finger pressure to turn the fan. And when the engine is running, the fan always seems to be spinning, no matter what the termperature is. I don't have enough experience to know if this is normal. I'm curious if others have experienced this, or if the "overcooling" could be caused by something else?

 

Hve you checked/changed your thermostat? Maybe it's not closing when cold

 

Thank you Red, and yes, I have checked the thermostat. I put it in boiling water and watched it open and then close. Also, I changed it recently and it didn't affect the performance at all. It seems to be doing its job by holding the ECT temperature at exactly 195 degrees, which is the rating of the thermostat. But I suppose it could get stuck in the open position. I'll try to check this. Thank you.