Temp gauge question

[Lowhoe775]

Hello i have a 78 c10 inline 6 (250). My temp gauge after it warms up stays a little over the first mark. I can run it all day and it does not move. Is this accurate for normal running temp. I think its too cool but i do not know anyone else with an inline 6 thanks in advance for any help

[74 C-10 Shorty]

Could be the sending unit??, but I would pull the T-Stat and check it on the stove in a pot of hot water, I always check new ones before I put them in even new ones are way off sometimes.

[81_Chevy]

it could be your thermostat, since it could be stuck open not letting the engine warm up, check that first. it could also be your gauge and or temp sending unit. also after running your truck for a while (if it has heat) check the heater hoses, the both should be around the same temp, fairly hot to the touch. if there not hot its probably your thermostat, but if they are hot its more than likely you sending unit/ gauge. has the truck sat for a while without being run?

oh and welcome to the forums! drop by the welcome section a make a post! 

-Nic

[travisr1988]

My '79 c20 with a 350 has that same issue. I'll replace the tstat and check the new one in a pot. If that isn't the issue I'll replace the sending unit

[rich weyand]

'78 K10.  Same thing.  Only time I saw it go up is when I had a coolant leak, and the sensor was uncovered.

[Lowhoe775]

Thanks a lot to everyone that gave me feed back i will try the tstat and go from there.. Ill post up the results thanks agiain

[Lowhoe775]

@81_Chevy the truck did sit previous owner past away and sat for about a year then i picked it up. It runs like a champ.

[Irish_Alley]

not going to guess but heres how to test the sending unit if your sending unit changes in resistance then it would be your gauge or maybe bad connection. if no change check your hoses like stated if you notice them changing temps after the gauge stops rising then it points to your sending unit

Special thanks to bd for providing info on this
TEST PROCEDURE - SENDING UNITS

The subsequent charts provide precise sender resistance values for three specific gauge readings (Low, Medium, and High), hence, can be used to estimate sender resistance when actual physical parameters are known (e.g., engine temperature that is verified with a thermometer, actual fuel tank level, engine oil pressure that is verified with a manual gauge, etc).  Therefore, a sending unit’s resistance can be measured and “subjectively” compared to its interpolated value between ‘Low,’ ‘Medium’ and ‘High,’ based on the charts and the observable/verifiable physical conditions that actually exist on the vehicle.

For Truck Years:  1974 - 1978

The Temp Gauge Needle Should Point to:
Left Line (Cold) when sender resistance = 350 Ω
Middle Line when sender resistance = 68 Ω
Right Line (Hot) when sender resistance = 46 Ω

http://forum.73-87chevytrucks.com/smforum/index.php/topic,25339.msg211241.html#msg211241

[travisr1988]

My fan belt (new one) broke the other day and my gauge definitely works, went up and almost overheated before I caught it, luckily I didn't throw the old belt away yet. I think the parts guy gave me a 160* tstat instead of a 195*. I'll have to be a jerk when I get the new one.

[Lowhoe775]

not going to guess but heres how to test the sending unit if your sending unit changes in resistance then it would be your gauge or maybe bad connection. if no change check your hoses like stated if you notice them changing temps after the gauge stops rising then it points to your sending unit

Special thanks to bd for providing info on this
TEST PROCEDURE - SENDING UNITS

The subsequent charts provide precise sender resistance values for three specific gauge readings (Low, Medium, and High), hence, can be used to estimate sender resistance when actual physical parameters are known (e.g., engine temperature that is verified with a thermometer, actual fuel tank level, engine oil pressure that is verified with a manual gauge, etc).  Therefore, a sending unit’s resistance can be measured and “subjectively” compared to its interpolated value between ‘Low,’ ‘Medium’ and ‘High,’ based on the charts and the observable/verifiable physical conditions that actually exist on the vehicle.

For Truck Years:  1974 - 1978

The Temp Gauge Needle Should Point to:
Left Line (Cold) when sender resistance = 350 Ω
Middle Line when sender resistance = 68 Ω
Right Line (Hot) when sender resistance = 46 Ω

http://forum.73-87chevytrucks.com/smforum/index.php/topic,25339.msg211241.html#msg211241

thanks for help so i checked the sending unit and it was working fine so i changed my gauge from one at a local junk yard and now it reads normal temp. So the problem was the gauge that was stuck and not reading correctly. Thanks

[Lowhoe775]

Problem was the gauge itself. Sending unit was fine and t stat was good too. If u have this problem try switching out the gauge. I got mine at local junk yard for 5.00 bucks easy to replace and now it reads normal thanks to everyone for the help