normal coolant temperature for diesel engine

No big deal, in about 4 weeks we won't need heat again until November. Usually that will cook us here in Florida. We just took a 4 hour trip, outside temp wasin the low 40's, and we had the heat maxed most of the trip. Another thing I forgot to mention is that the heat is rather weak, another indication it might actually be running in the 160 range. I will pick up an infra red and check the temps to verify actual operating temperature.

The odd ball tick marks tends to make me misread the temp reading. Like Chickenhunterbob says double check accuracy of dash gauge. Most quality thermostats will open within 3 degrees below and 4 or 7 above temperature and They open pretty far pretty fast its not linear mostly open or closed but should go fully max open at no more than 15-20 deg above set point. The engine (fuel burn) will run better at 195 but underhood temps will be higher and harder on the electronics. Its a trade off for electronics trucks which is better and depends on usage and climate of local. Some use 180 Deg thermostats (I have dual 180's and run right about that for temp) I think 195 was OEM. The ECM resets injection time at 170F from cold start advance IIRC. Minimum temp for stable operation is 160F per specs and should be reached within 10 minutes of start up or the ECM with set the service engine soon light. I think i remember the dash gauge is in the head the ECM sensor is in the cross over. The PCM measures engine coolant temperature independant of the dash gauge. Synthetic is no doubt better, but considerably more expensive, and the 6.5 will dirty your oil in one trip around the block, so I like to change every 2500 miles. Oil? I don't know, I just use Rotella 15w40 dino, but with oil you are liable to get as many opinions as there are types and brands of oil. It should have a hose hanging down along the water pump not connected to anything at the other end, put this hose into a container of some sort before opening the valve, to avoid the mess. This is connected to the fuel filter housing by a rubber hose, and is to drain water form the fuel filter. There is a small brass 'T' valve near the thermostat housing at the front / top of the engine on the coolant crossover. Or it could be the thermostats are not closing, but verifying the actual coolant temp (rather than what the gauge reflects) will verify. The gauge on the dash are not always accurate, if the actual coolant temp is considerably different than the gauge reads, as often as not, the cause is the sending unit up near the front in the driver side cylinder head. If you are seeing lower temps, it may not necessarily be the thermostat(s) that are at fault though, you could verify the coolant temp after the engine warms up if you had access to a tech 2 type scanner, or a infrared type thermometer pointed on the engine side of the thermostats. My single set up oem is 195, I think the dual t-stats on the later models are too, not entirely sure though. Normal temp should be around 195, or so, depending on the thermostats that are installed.

Normal coolant temperature for diesel engine