my temp started fluctuating, loaded and unloaded, changed thermost, still doing same, changed temp sending unit, still same problem, fluctates like an oil pressre gauge from 187 to 210, im driving 70 mph temp is fluctuating between 200 to 210 and its 50 outside, any sugestions......?????

 

My first guess is the new t-stat is crap. Where did you get the new one??

 

Is it possible the T stat is cycling like it is supposed to? Does the cycle time increase/decrease with load and outside temperature? Did you take the T stat out and test it with a kettle or pot of water on the stove to see if it is opening closing properly? Is the highly accurate dash guage good? Is the fan cycling under hot water conditions indicating water temp changes?

 

Fill out your signature. What truck and motor do you have. If it is the 6.7 then it is certainly possilbe that the regeneration cycles are causing this temperature fluctuation and there is nothing wrong with the T-stat. Mine fluctuated like this for no reason that I can tell other than the motor was going through a regen process. However, that all stopped when the emission system stopped working and I had to remove it for cleaning and testing . I have a "temporary" solution in the Smarty ME to get me by these tough times until the emmisions systems are fixed and find their way back on to the truck for any warantee work needed or smog checks that present themselves.

 

I have experience air pockets causing readings fluctuations. You might want to double check that.

 

I have an Edge Insight on my truck and I will state that the temps will hit 200 to 212 during a regen towing. Then when its done, its back to 189 to 194, floating around somewhere in there. That being said, if its constantly floating that high, there is an issue with the thermostat. Did you get a genuine one from Cummins? Also, could your rad be partially blocked?

 

Sounds normal to me. Mine does the same thing.

 

I too have read of this cycling being associated with the regen process.

 

This sounds normal to me. Mine does the same thing. Over the years, I've learned what the normal range is, and I don't worry unless it exceeds that (hasn't yet).

 

It's normal.

 

Well, I don't know that it's normal. If we remember, lots of us thought the fluctuation was normal on the second gens too until Cummins came out with a different thermostat to take care of the fluctuations. My question is, do we have anyone who can certify that the fluctuations are attributable to anything... i.e., when the engine goes to regen mode.

 

I can guarantee that when my truck was in a regeneration, the temp would sit at 210. Since my emissions system failed, that issue has gone away.

 

one thing frustrating is that the 6.7 is smaller coolant capacity than the 5.9. 6 quarts is a lot of difference. finger they did that to keep things hot for emissions garbage along with the innercooler on the 09-newer trucks.

wonder if finding a way to get another 6qts in our systems would help any. just a thought

5.9L Diesel Engine 28.22 qts.
6.7L Diesel Engine 22.6 qts.

 

here is a list of Chryslers possible causes for

TEMPERATURE GAUGE READING INCONSISTENT (ERRATIC, CYCLES OR FLUCTUATES)

NOTE: Information on dash cluster is displayed based on broadcast data from ECM. DTC will be set for engine sensor circuit wiring.

1. Heavy duty cooling system, extreme cold ambient (outside) temperature or heater blower motor in high position.

2. Temperature gauge or sensor defective.

3. Temporary heavy usage or load

4. Air trapped in cooling system.

5. Water pump.

6. Air leak on suction side of water pump.