Hey guys i have a 6.5 turbo intercooled it is the mechanical injected optimiser, first hard long run away 3000 kilometres in total. Towing a large boat averaged 23lt to the hundred kilometre (10.22 mile to the gallon) had one day of around 30 deg Celsius (86F) motor got to hot to run the air con without overheating. Kept the turbo temps (post turbo) to max 420 C did note that the heat build up in the cab was getting up there so the motor was working hard.
So here is the rub guys who supplied and installed engine say they want to
A. Change out the viscous coupling on the fan to constant lock up
B. Take out the small engine oil cooler they installed and put in a Kenworth oil cooler (yet to sight this so can't give much more info on it they will install this along the passenger side up against the floor)

I know that i am pushing the limits of the tow vehicle with this boat (intend to sell it anyway) but will be getting a caravan around the twenty odd foot instead, and changing down to a car top dinghy. I know that i will hit days way worse then what i had towing the boat so would like opinions on the proposed solutions to curbing the heat.



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I would just go with the Kennedy special calibration fan clutch and 20" fan,it is designed to engage sooner to keep temps in check and works well on my truck.

The earlier fan engagement will also help with the oil cooler so stock size should be fine provided yous has a stock size oil cooler.

make certain that all the coolers and rad are spotlessly clean and no debris between them.

Also AC Delco only for thermostats.

 

Thanks for the reply will talk to the dudes about your recommendations, they did install their own custom radiator which is quite a bit larger than the original will check the clutch on the fan with them. The oil cooler to my mind is a bit on the small side only big enough to increase the oil capacity by about one litre.