1. I have a 2010 Sport Hemi with Trailer Tow iv package, which as I understand is rated at 7200 lbs. How come the sticker on the door says not to exceed 1300 lbs of occupants and cargo?
Internal Cargo rating and TOW rating, they are different.
People that bought late 90's Ford Explorers, never checked those figures, if they did, the likely would never have bought them, the rating was so low (I think the internal cargo rating was like 750lbs or there abouts) you couldn't fill all the seats with adult men, you could carry normal sized passengers or some luggage, NOT both. Of course no one bothered to follow that, nor even figure it out, throw in bad firestone tires, underinflated (to mask the rough truck suspension) and NOT checked or topped off by the owners so the tire pressure went dangerously low with overloaded vehicles, and you got the fiasico that nearly ruined Ford and arguably did ruin Firestone, that is NOW just a subsidary of Bridgestone.
And we get to pay extra money and aggrevaition for the Federally Required TPMS system that you see so many posts complaining about. Because the Federal Government decided we all must be idiots like those couple Ford Explorer owners.
2. QTII 4x4 system - no friction modifier needed in either axle when changing the fluids?
I'd confirm it is QTII and NOT QDII, but yes, if they are open differentials there is NO need for the fricition modifier, and NOT only is it cheaper, if you don't need the friction modifier then the oil in the diff will arguably be a tiny bit better at lubing your diff. (NOTE, if you need friction modifier use it, clutch packs don't work right and wear out super fast without it).
3. I got the build sheet for the truck and was surprised to see that the tow package did not come with a transmission cooler. How come? Doesnt say anything about an upgraded cooling system either? (does mention a power steering cooler though)
I think, BUT DO NOT KNOW, that the Commander V8's come with heavy duty cooling as standard equipment. So the Tow Package does NOT need to add extra cooling. It appears the Tow Package is just the extra transmission modes and buttons for Tow Modes and I believe they beef up the rear suspension for tongue weight and handling with a Tow load.
4. The cooling system in my Durango was very simple - a clutch fan attached to the water pump and an auxilary electric fan.HOw does the fan function here? It says to be working off the power steering fluid? Just trying to understand how that's possible and what the advantages are.
This also surprised me, the first couple times I saw people post about the Power Steering Hydrualic Fan, I was replying they must be wrong and thinking of a Vicsous Clutch Fan.
I guess they have been using this on Pick-Ups for a couple of years now.
Electric Fans have a limit, you get to a high enough air flow, they just aren't efficient enough and get really expensive. Engine driven fans are never efficient, the Viscous/Hyrdaulic Clutch Fans improve that, but nearly as much as an electric.
I guess the Hemi is so crammed in and lacking so much space, they couldn't even fit an engine driven fan and an electric fan big enough to handle the load couldn't fit either, or was too expensive or just doesn't exist. So they used a hydrualic fan, and the PS system is a readily available hydraulic system, just tap off the hydrualic supply from that system.
The Commander has a new PS fluid spec, its only available from the dealer, and usually when the manufacturer uses and recommends a new kind of fluid for a system in their vehicle, it is because no other existing fluid can stand up under the demands of the new system. I "suspect" the Hydrualic Fan is the reason for the new PS fluid in the Commander, but I have NOT found anything to confirm or deny that, Jeep recommends the new fluid for all Commanders whether they have the hydrualic fan or NOT.
Take most of that with a grain of salt, most of it is what I see posted on the boards, some of that info may be wrong. Other please correct me where I'm wrong.