That and the overflow valve

The statement from Cummins I posted was on an attachment that was stuffed in the owner's manuals when the trucks were new.
Dealer was also instructed by Cummins to tell new truck buyers about the totally normal temp swings.

Problem now is the majority of people who own 12 valves probably bought them used and never were told or the manual addition is missing...

Guess Cummins finally got tried of hearing complaints and moved the temp sensor in 1998. The newer ones still fluctuate but not as much
(at least at the new sensor location, actually nothing has really changed).

I sort of like the temp swings, it tells me the thermostat is working.

 

But then why would it start doing it when it had not done it before without even a major change in ambient temperature? That doesn't make sense to me. It says it will fluctuate, not bounce. I'd translate that as sometimes the gauge will read higher than other times depending on conditions and ambient temperature. That would hold true for another diesel that I own as well.

It seems there is a coolant temp sensor and a coolant temp sender.

Can I humbly ask for a clarification as to the function of each? They are both listed as being on my vehicle.

I suppose the next step (once I determine which sensor/sender is related to the gauge( would be to use my remote thermometer to verify if the temperature is actually bouncing up/down by 50 or so degrees.

 

Funny thing, on Brownie, with the original thermostat, I get the swings, have done so since day 1 of my tenure as her guardian.
Greenie, built just 216 trucks later had no heat when I got her. At some point in its life a piece of gasket got between the body and the blade of the thermostat and held it open less than 1/16" of an inch. It would NOT get hot enough to defrost the stupid windshield. I put a 190 degree NAPA premium thermostat ( all I could get at the time ) and she now is pretty steady at 180 indicated. I think it is more a function of how the thermostat opens, and given the huge cooling available, very little thermostat opening cools dramatically.

That's my take on it anyway.

 

Interesting.

Any idea why the 180 degree seems more prevalent?

By any chance there wouldn't be a post relating to sensor locations or a jpeg or something would there? I haven't found one by searching thus far.

 

Sensor and sender are just different words for the same thing.
Coolant temp sensors on these engines rarely fail but the connector to it can come off or get corroded. It's sort of hard to get at being on the rear of the engine.

 

Infidel, you never fail to deliver the goods. Excellent diagram.

THANK YOU.

Hmm. Would you care to comment on the two categories of apparently the same part available on rockauto.com for a 1995? I assume at this point that one is miscategorized by year but would value your confirmation.

I think of one a a one-wire resistor deal and one as a two-wire 5V reference type thing for the computer. I suppose one could be for the electric radiator fan should one actually exist...

My new radiator should arrive tomorrow and then I can test for actual temps at rear of head. I don't understand why this would just start or increase in pronouncedness one day...

On a side note: hey, that's where my starter is? Golly, never woulda spotted that.

 

If the temp senders are anything like the the oil pressure senders I wouldn't buy a generic one from the autoparts, they don't last.
Go to Cummins and pay more one time rather than paying even more when you have to do it twice.
If the temp senders are like the oil pressure senders a special sensor socket makes it easier.