temp gauge fluctuation on 95 s-10

[GEP]

I am working on my mom's 95 S-10 with a 2.2L 5 spd.
She had a overheating problem with it, I replaced the head gasket(it was leaking) t-stat,fan clutch(I could stop it with my hand,it was moving slow) it was still overheating after this, I pulled the radiator, the bottom cores were plugged solid. I put a new radiator in and now the overheating problem is gone, but now the temp gauge will fluctuate between 1/4 to 1/2 of the gauge, about 185-210, I checked the scan data and the engine temp reads about the same as the gauge. The fluctuation is pretty constant, goes to about 210 then back to 185 and keeps going this way. I put another t-stat in thinking the new one was bad, but I still have the same problem. I was thinking about putting a sensor in but the money is starting to run tight and I hate to put more parts in. Any ideas?

Thanks,
Glen

 

[bgott]

Check your 5 volt reference to the sensor. You might also want to check your grounds, you might have left one loose when you had the head off. How is the water pump? You might have an impeller spinning on the shaft and the engine is cooling by thermosyphon. Have you driven it and seen how it acts? Any air in the radiator after you let it cool and check the water? A cracked head can blow the water away from the sender and cause it to read low, water can be surging around the sender. How do the rest of your gauges act? If you have a problem in the panel your gauges can react too quickly. Does the gas gauge swing when you go around corners and your oil pressure gauge needle swing like a tach needle when you rev it? You might want to remove the thermostat and test it with a thermometer and a pan of water on the stove. I've had lots of screwy thermostats right out of the box. The cheap ones are the worst but I've had bad Stants, too. Why did it blow the head gasket in the first place? You might not have fixed the root cause yet. I bet you were looking for an easy answer, weren't you? /forums/images/graemlins/tongue.gif

A little trick to make bleeding the air out of the system easier...Prop the thermostat open with an aspirin table when you install it, it lets the coolant push the air out so you don't have to watch the temp gauge peg before the thermostat opens the first time and then it dissolves so the thermostat will work. /forums/images/graemlins/wink.gif