D-Max Engine Temp. Question

[DennisG01]

I had a chance to tow with a 2004 Dually last nite. It is our work truck at the marina. My question is in regards to engine temperature. Unloaded I had the cruise at 72mph, 2200rpm and the engine temp was rock steady at 205 with tranny at 145. Neither moved AT ALL. OK, I figured that would change when I pickep up the boat (granted, it is only about 6,000lbs - 1989 Baja 240 Sport). With boat in tow, set cruise at 72 mph again. Engine temp stayed the same, tranny was 155, but both were again rock steady. There were some hills, but nothing major.
My question is, is that temperature "steadiness" normal? My 6.5 is never steady.

[markrinker]

'Steadiness' indicates a well designed system that has good flow, so there is little to no variation between coolant temps in the block and in the radiator - once the whole system is up to operating temps.

[carco]

My experience w/ 6.5's is that the gages are a little too sensitive to fluctations of temps and the 6.5's are overly prone to temp differences while driveing. Pulling hills adds heat and the
6.5L cooling system doesn't flow the best. Your D/A sounds OK. bob...

[DennisG01]

Thanks, guys. I guess I'm just so used to seeing constantly varying temperatures with the 6.5 that when the 6.6 didn't vary at all, I thought something might be wrong!

[mark45678]

Engine temps on lb7/lly 6.6 trucks are rock solid, you may see the gauge move 1 line and the clutch fan will kick in on a hill but the most I have seen is 219*f with the AC on 9% hill for over a mile at 72 mph with a 7300# 30' camper in tow (89*f day)! the fan comes on around 215~219 and cools it off quick, it will never get hotter once the fans on....