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

Try Cleaning you Mass Air Flow Sensor or maybe your not sucking enough air try changing the air filter whens the last time you changed it? if it has 128k i can imagine how bad it is if you havent changed it in awhile

Could have a head gasket going or gone.... Any steam or antifreeze smell out the tailpipe. Missing at all?

I have a 97 S-10 and just recently went through the same thing -- suddenly heat temp would climb, hold and then drop. Eventually climbed and overheated. Stopped and it cooled down. Now it just varies widely and have been told it's the head gasket. Getting it replaced in 4 days. Will let you know if it's the problem. PS: No smoke when driving however.

In order to determine if you have blown head gaskets there are some easy ways to find out. 1) is there antifreeze in your oil? or vise versa, you can check this by taking your rad cap off, oil will float on antifreeze, or is it bubbling excessively (from the compression)...also do an oil change and look for seperation, dump the oil out of the catch pan slowly and when it's almost empty look at the bottom for antifreeze. 2) does your exhaust smell sweet or is it smoking? 3) are your spark plugs wet and greasy? any one of these things will indicate a blown head gasket. You mentioned about a rad flush...i would do one before getting into a head gasket, if the coolant cannot circulate it will not cool down. The only thing that bothers me is the constant fluctuation in temp. the sensor either works or it doesn't so i don't think it will be that. Hope that helped a bit.

Have the same problem. I have had it for about a year. never actually overheated on me i wouldn't let it concern you.