While towing a 3700 gross lbs camper with my 3.6 L 3.55:1 big horn crew cab on 5-6% hills, I often get to where the temp gauge starts rising. To avoid a temp warning I need to turn off the A/C and/or slow down to 40 mph once I see the needle start moving upwards. I have not been looking at the individual fluids detailed display. Bottom line is the issue doesn't affect total trip times much, and I can live with it, but naturally I am interested in ways to improve cooling. I went to a shop that does nothing but radiators and mufflers. I asked about the affordable third party radiators. I could have one installed for just $100 labor. Cheaper than cleaning the original radiator. The guy advised strongly against it. For the given overall size of the radiator, performance depends on the number of straight tubes that run in parallel to conduct the fluid from input tank to output tank (surrounded by vertical cooling fins). The replacement units have fewer tubes in parallel, and cooling is correspondingly worse, as evidenced by poor results seen in customer vehicles. I had the shop take my (original) radiator out. I was told it is a very fine radiator, and identical to the one used for the hemi. I had them remove the (plastic) tank on one side, and stream water from the other tank. Water was seen coming out equally from all of the little tubes. Thus: no blockage. Had there been any, the standard procedure at this shop was to clean inside the little tubes mechanically with a straight metal wire. I asked about chemical cleaning. I was told that chemicals are appropriate for brass/copper radiators, but not for aluminum. My radiator required no cleaning on the inside, but some dust accumulated on the outside of fins (in a limited area) was removed. I guess I could have done this myself with a water or air hose.
I am not a gearhead, but as an engineer I am curious to learn about all cooling functions in to my vehicle, not just engine cooling, but also transmission cooling and A/C cooling. I have asked questions at a couple of dealerships and learned nothing. Maybe someone here can help me understand the basics.
I recall that when I purchased the vehicle new, I was told that an extra transmission fluid cooler was part of the included tow package. Where is the standard transmission fluid cooler located? Is it part of the radiator? And where would I look to see the extra transmission fluid cooler? Is there also supposed to be a cooler for the engine oil? And what is AGS? Where does the A/C dispose of heat?
Towing more weight, on a steeper grade, at higher speed, expends energy at a higher rate, regardless of the particular engine doing the work. If I had a hemi doing the same towing job, and if its efficiency were the same as the pentastar, then the radiator would have to radiate the same amount of heat. My guess is that the hemi would generate a bit more heat to do the same. I have been told that the actual radiator would be the same. Yet I have the unconfirmed impression that people with hemi's would be able to tow more up those same hills, with a bigger trailer,without overheating. Why? Maybe the fan (fans?) send more air through the radiator? If I set the vehicle idling from cold, after a while the fan comes on, but seems to run slowly, and not making the kind of roaring noise that my old chevy V8 would make when the mechanical clutch kicked in. Maybe for the V6, the fan is run at a slower speed when running at all? I tried to find out about how fan speed is controlled. It is hard to find information online. I found one article from a Wrangler owner who stated that on the Jeep, there is only one fan relay used, and it just turns off the fan, or connects the full battery voltage. The third wire going into the fan's electronics was said to carry a pulse modulated control signal to tell the fan how fast to run. The wiring on my fan looks just like that in the article. Could it be that the RAM fan works just like on the Wrangler? At this point I consulted a local mechanic for a fee. He had access of official RAM documentation. It didn't really explain things, but there was a wiring diagram. It confirmed the single relay, single voltage used for running the fan. However, the third wire was labeled to suggest the it tells the computer about the actual fan speed, rather than letting the computer tell the fan how fast to run. I would really like to understand whether the fan is supposed to run at more than one speed, and how this is done.
It seems that I am not the only one interested in better cooling. We all drool about horsepower and other specifications when we buy a vehicle. Why is there no numeric measure of cooling capacities among commonly listed spec's?
Look above!
