93 S10 Blazer running a bit hot

I have a 93 S10 Blazer with approx 128K miles. Just over a week ago I noticed the engine was running around 10-20 hotter (210-220) than normal and I added just over a gallon of coolant to the radiator. The car had always run right at 200 according to the dummy lights and has run between 200-210 ever since. It will go up to 210 when running, dip down to 200 when stopped, and vice versa. It will run at 210 consistantly for 30-40 minutes and then dip down to 200 for a while and then back up. It hasn't overheated (or gone over 220) but this change has me puzzled. It never went over 200 until this past coolant adding episode.

I have replaced the thermostat, water pump (it had a small leak), and even the radiator cap but it still deviates from 200-210. is this something I should even concern myself with? Could it be a sensor error? I haven't flushed the radiator. Could this help?

Thanks!

Rob in Florida

Flushing the system helps. Make sure you do it correctly!

Also, A 50/50 mix of coolant is optimal.

Straight coolant will mess up the engine.

Also could be the radiator cap. After time, they lose their sealing ability, because the rubber gets old, and won't keep the proper psi.

Theirs a shot in the dark. :dunno:

Robert