2nd Gen Non-Engine/Transmission anybody find early style temp gauges reading high?

[WDixon27]

running unloaded interstate it hangs around here

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different 180 degree thermostats don't effect its range, radiator is aluminum clean and around 4 years old, changed the temp sender water pump and fan clutch at about the same time too as preventive maintenance, the hoses never feel hot and hard like its running over 200 and it doesn't loose coolant

 

[mnick]

WDixon27 I run a stock temp gauge in my 1996 and also a Autometer electric temp gage with the sender at the front of the engine. Temps will run within 5 degrees of each other. Truck has 150,000 miles on it and orginal sender and gauge have never been replaced. Temp is around 185.

 

[Nyoest]

Running I 70'east with 35 ft 5er at 75 mph in june I can't hit that temp. You might try installing a temporary mechanical gauge to verify actual operating temp. Or get it to temp and measure the resistance of the sending unit and verify the resistance.

 

[SFPADGETT]

We replaced a broken temp sending unit about 1 month ago with a NAPA unit. Now it reads high (similar to yours). We swapped the unit with another truck with factory sending unit. The new NAPA unit is reading high--it wasnt the truck.

 

[WDixon27]

got mine from the local dodge store but that don't mean its good, was thinking about swapping in a standalone gauge for testing but not sure about a adapter as i remember the factory unit being pretty huge compared to most automotive temp senders, haven't gotten around to looking for a handy plug or some other place to screw one into, had a notion to drill and tap the thermostat housing

We replaced a broken temp sending unit about 1 month ago with a NAPA unit. Now it reads high (similar to yours). We swapped the unit with another truck with factory sending unit. The new NAPA unit is reading high--it wasnt the truck.

 

[mnick]

Below the t-stat housing is a plug. I removed it and used a common brass bushing to reduce the size so I could install my autometer temp gauge. Hope this helps.

 

[mnick]

I installed the temp sending unit there, not the gauge. The sending unit is a little larger in diameter than a pencil.

 

[WDixon27]

in the middle of re doing the head gasket due to crap studs failing and used the chance to test the sensor in boiling water and heres where it reads
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nice damn thing never really read correctly but has steadily gone higher in the 4 odd years since i replaced it when i did the gasket the last time and snapped the plug off the old one. if this pic is 212 then where it reads in the 1st pic in the thread outta be about 180

 

[BSeyler]

I'd shoot the thermostat housing with an infrared thermometer and see how it compares to the gauge. Maybe a shot on the block where the factory sending unit is, also.

 

[Ram4Sam]

Just for chitz and giggles, try a 190 thermostat and see where it runs. While I'm not sure if I believe it but a much older mechanic(who I learned a lot from) used to say that 180 stat was opening and closing more often and the water in the radiator wasn't there long enough to cool down completely before the stat opened and sent the hotter water back to the block. Again, not sure of this theory but maybe somebody smarter than me might know... .



Sam

 

[WDixon27]

180* t-stat runs at about 180 at the housing, thats why i haven't been panicking for the last couple years of it reading around 230 unloaded on the interstate

I'd shoot the thermostat housing with an infrared thermometer and see how it compares to the gauge. Maybe a shot on the block where the factory sending unit is, also.

 

[WDixon27]

got her back on the road with a new temp sender (and 6# bypass for what its worth) and gauge is in the exact same spot so its not the sender, does anybody know if theres some sort of voltage compensation circuit for the temp gauge or is it a direct circuit of power-gauge-sender/ground? i know older stuff will have a regulator circuit that can screw with the gauge and odd the way this thing has slowly crept up over the last couple years is strange to me but not sure of that kind of thing survived up as late as my 96, i deal more with bmws and volvos

 

[Missouri Mule]

WDixon27, Direct line from sender to gauge. Works off resistance.

" The coolant temapture sending unit is a thermistor that changes electrical resistance with changes in the engine coolant tempature. " " High sending unit resistance causes low coolant tempature readings. Low resistance causes high coolant tempature readings. "



Temapture Gauge Calibration.

Low Normal (+/- 3) 155 ohms

High Nomal (+/-3) 80. 9 ohms

 

[WDixon27]

cool so the gauge is crap, kinda figured that. couldn't find squat in our shop software or online on resistance values to diagnose, just how to replace it