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Discussion Starter #1
Today while driving my 1995, 6.5, I noticed that the temp gauge would jump to around 210, then above, then below, all very quickly. Then it held at around 210 or slightly higher for a while then dropped to slightly below, all while maintaining the same speed (unloaded on level grade). Truck has alway been rock solid on temp gauge, unless towing. The temp usually always holds at around 2-3 clicks below 210 and never budges. No problems with radiator and all is clean. Any chance the problem is the thermostat or sending unit, or possibly a bad water pump?????? Anyone else had these problems???

:mad:
 

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How fast does it 'jump'? I can tell exactly when the thermostat opens and closes on mine, I would call it a jump because it drops ~20F in just a few seconds. But if it literally jumps then its an electrical problem, either the sender, wires, connections or dash gauge. I would start with the connection sender, its on the front of the driverside head by #1 injector.
 

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Discussion Starter #3
How fast does it 'jump'? I can tell exactly when the thermostat opens and closes on mine, I would call it a jump because it drops ~20F in just a few seconds. But if it literally jumps then its an electrical problem, either the sender, wires, connections or dash gauge. I would start with the connection sender, its on the front of the driverside head by #1 injector.
TDG:

The first jumps I observed were fast (not like you see when the Tstat opens). That alone would pretty much make me think it was electrical, however, later, the temp held at around 210 (which it never does unless loaded on a grade). In the past, any time the temp reached above 210 for any length of time the fan clutch would engage, which it never did today.

Is the sending unit difficult to change???? Can you better describe where it is located and what it looks like???

Thanks for the quick reply!!!!!
 

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I just replaced the same sensor. (Had same problems only going upt to 250) Drivers side toward the front above the ps pump. Took me all of 5 minutes to find the right tool, remove, install new sensor and check for leaks. No leaks observed. It is a one-wire unit, Advanced Auto carries a 2 wire unit which is for the coolant temp sensor mounted up top. Got mine at carquest for around $10
 

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I just replaced the same sensor. (Had same problems only going upt to 250) Drivers side toward the front above the ps pump. Took me all of 5 minutes to find the right tool, remove, install new sensor and check for leaks. No leaks observed. It is a one-wire unit, Advanced Auto carries a 2 wire unit which is for the coolant temp sensor mounted up top. Got mine at carquest for around $10
Thanks TRIAZ. I'm replacing mine tonight.

:ro)
 

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Discussion Starter #6
The new temp sending unit appears to have worked. Thanks to all that provided input.
 
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