Posted: Aug 15 2011 at 4:12pm | IP Logged

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I have a window bug screen behind the grill and in front of the two cooling cores. The screen reduces the air flow. So if I have a heating problem I can remove the screen. I've made many trips to the Colorado mountains of 3,000 miles climbing long steep highway grades (like 7.5%) and did rocky off road trails going over 14,000 feet with up to 40% grades. My '99 3.3 V-6 has never gone over the mid range heat mark.... Knocks on wood (head)...

The screen keeps the bugs out and pebbles can't bend the cooling finns!

If you have an auto tranny you can mount a pre-cooler under the truck away from the exhaust so you don't dump a lot of tranny heat into the cooling system! Putting tranny coolers in front of the radiator doesn't make any sence...

Good Luck.. Don S..

Posted: Aug 17 2011 at 9:15pm | IP Logged

ddman,

If the only time the engine runs hot is on the highway, then there's a 90% chance that your problem is the radiator. Remove the radiator cap and look at the individual cores (rows) in the radiator, if you can see a buildup of crud on the cores, then I would either send the radiator out to be "rodded"  or buy a new one. Usually when a radiator plugs up, you can't really see anything plugging it because it plugs down in the middle of the core. If you have more than 75K miles on the parts, then also replace the hoses, t-stat and of course the cap.

Good luck!