Operating temp

[Shikaroka]

What is the "normal" operating temperature for a 6.5TD?

A 195 degree thermostat is stock, right? So, it should run right around 195, right?

Do these engines use a coolent temperature sensor to supply a signal to the ECU, (like a gasser, to adjust the mixture)?

[moondoggie]

Good Day!

"What is the "normal" operating temperature for a 6.5TD?" ~ 195F

"A 195 degree thermostat is stock, right?" I think so "So, it should run right around 195, right?" Uh, yeah.

"Do these engines use a coolent temperature sensor to supply a signal to the ECU..." Sorta. On my 95's (& probably on your 96), there are two temp sensors: one for the gauge, another for the PCM. "...(like a gasser, to adjust the mixture)?" You own a diesel now, forget the word "mixture." Ever seen a throttle plate on your diesel? A diesel ALWAYS runs extremely lean; when the amount of fuel starts to catch up with the available air, you get black smoke. Your diesel intakes all the air it can, all the time.

The PCM temp signal controls various things, like idle speed, etc.

Blessings!

[Shikaroka]

I know mixture means very little to a diesel, that's why I said like on a gasser.
But, what does the coolent temperature sensor control?

I ask because, my truck never gets over 180 degrees, even in the summer.
On a gasser, if the coolent never gets up to temperature, you run into problems like running rich. So, I'm wondering if there are any issues here.

I'm starting to think I have a stuck thermostat or something. I need to check it out.

[Dvldog8793]

Howdy
The factory gauges can be off by a good amount. Never hurts to replace the stat and flush things out while you're at it. Make sure you get a GOOD stat. Check on JK's web sight.
I think the only reason for the ECU to need temp info is for over heating issues. It also uses a intake air temp sensor to monitor engine temps.

L8r
Conley

[rjwest]

Previous owner probably installed a 180 degre Stat,
If you are towing or running heavy, 180 probably a good idea,
but you will loose a slight bit of MPG without the 195,

Diesels make more power with the same fuel rate at higher temps...

[Hubert]

clipped:

But, what does the coolent temperature sensor control?

Anyone have further info on this than....

The ECM controls timing and idle (fuel rate) according to engine temp. Mainly I think its a big difference below or above 160F +/- some maybe. 160F is considered minimum temperature for stable operation. Then at the hot side ECM will limit fuel as an attempt to safeguard against melt down.

The difference between 180F and 195F should not really effect ECM program that I know of. If I am wrong someone post please.

The difference in 180F and 195F is thermodynamic effeciency of the engine cycle. I thinks its the warmer block helps add a little energy to the cold incoming air.

There is a whole host of trade offs due to engine temperature: Fuel temp (IP lives in valley of engine), electronics temperature, intake runner temps, oil temps, and being able to control temperature gradients etc. 195-205F seems to be a sweet spot for effeciency - 180F seems better for electronics, IP longevity, and head gaskets maybe.

[Shikaroka]

Previous owner probably installed a 180 degre Stat,
If you are towing or running heavy, 180 probably a good idea,
but you will loose a slight bit of MPG without the 195,

Diesels make more power with the same fuel rate at higher temps...

Yeh, that's what I was thinking.
Thanks RJ (and everyone else)!

[rjwest]

I am guessing that 170 degrees is a 'majic' number, as this is the
temp the PCM looks for before initiating a IP TDCO learn...

[Bnave95]

Any one know if timing changes with higher coolent temp?
Just wounder that my Off set was timied when running 180 deg. stats.
Now running with 195. I think not, but know Coolent temp on manfold also for cold start advance.