Coolant temps in my truck are almost always 194°-197.6° according to the UltraGauge, summer or winter in North Carolina. The temp will sometimes creep up to ~200° in summer at a stop light, and will occasionally be less than 194° when cruising in winter but those are notable exceptions.

Those temps are with a standard thermostat installed 2½ years ago when I changed the head gaskets. The truck now has 132,500 miles on it. The radiator was replaced eight years ago today (coincidentally) at 60,770. The fan clutch is original, as is the water pump. Switched from Dexcool to green Prestone when the thermostat was changed (although Dex had not given me any problems).

Contrast that with a friend whose 2004 DII runs consistently in the 204°-215° range, even with a new radiator, thermostat, fan clutch and water pump in the last three years.

 

Or, the inline thermo mod brings temps consistently in the 180 range on road, and sometimes high 190s in slow high load situations off road.

 

Thanks everyone!

Still have one question not answered: Is replacing the thermostat a DIY job? If it is, what is the difficulty level on a scale of 1 to 10 (10=very hard) and estimated number of hours?

Regards

Al
'03 D2 SE7

 

it probally a 2 on a scale 1-10, bleeding the system properly of air afterwards takes more time than changing the t-stat.