Hi Craig, that's a nice looking truck
180-190 doesn't sound bad, but I might expect lower since you have an aux cooler with fan. Are the temps you're seeing with the fan off? I found my trans heats up most at lower speeds going uphill in Drive (lots of slippage).
Here's kind of a rambling account of my observations... I have an '01 4x4 with stock suspension and tires, 139k miles. I started measuring trans temps when I bought it June 11th, via Torque Pro which uses the internal sensor. It has 4R100 with tow package, it had the stock auxiliary trans oil cooler. I don't know what normal 4R100 temps should be, but I consider anything below 190-200 to be pretty good when it's 105+ degrees out, for my trans and tc in their current condition.
I found the following variables to influence trans temp: Location of temp sensor, individual trans and tc condition. Stop n go or slow driving in Drive, on or off road, with lots of slipping had most influence. Highway driving at speed on rolling hills when trans shifted often between OD and 3rd, lots of slipping between tc lockup I would see trans temp rise. Consistent low speed in low gear would tend to cool the trans even on steep hills as rpms were higher and tc was at or closer to stall speed (~1700 rpm for stock tc? not sure but that's what I think). Consistent high speed in OD or 3rd with tc locked up would tend to run cooler. Least important was ambient temps, seem to help keep trans cool but it would heat up regardless if there was lots of slipping (stop n go driving in D, uphill).
Here in Phoenix, daily temps were high 90's in June, to now when it's frequently 108-113 degrees. Through June and up until last week, trans temps driving around town were 190-203, occasionally up to 206 after long stop n go traffic. Highest trans temp was 227 on I-17 north with 103 degrees , there's a long uphill grade and there was heavy stop n go traffic; my ect hit 220 and trans temp hit 227; ac was on full blast too. I also did moderate off road driving (rock steps and obstacles up to 12") up some long hills (Harquahala Mtn, Schnebly Hill Rd, Senator Hwy/ Crown King). Trans temps would frequently hit 210-215 driving off road in D.
To manage the heat I experimented with driving off road in low gear to keep rpms up, tc closer to stall for less slippage. 4 low was particularly effective at keeping trans temps lower going up steep, miles-long hills, even if I could have driven up in 4H, the trans tended to run cooler at higher rpms. On long rolling hills at hwy speed I started using the OD button to keep the trans in 3rd with tc locked up and that was great. I want to convert the cruise control on/off steering wheel to tc lockup switch. If I can lock up tc in 1st and 2nd it would be great for low speed engine braking downhill off road plus reduce slippage overall and probably run cooler. Although I don't detect any slipping in these gears by seat of the pants, if I can lock up tc in 1st and 2nd I can graph and compare vehicle speed and engine rpm to compute gear ratio and see if it's varying which could indicate slippage.
Last week I installed a Hayden 679 (11x11, plate style) with aux fan in front of the AC condenser. Haven't hooked up the fan yet, but adding the additional cooler reduced temps 25 degrees overall. Last weekend I drove up I-17, stop n go on the steep uphill towards Prescott, then further uphill into the mountains on Poland Rd and up Mt Union on a lovely steep moderately rocky trail. Trans temps remained below 190 during the entire drive. Ambient temps were 111 starting in Phx and 85 at 8000' top of the mountain. Also drove thru Florence Box Canyon the other day, ambient temp was 109 and trans temp did not exceed 190.
To combat the heat I plan to drain and replace trans fluid every other engine oil change (about every 10k miles).
I can graph and post some data if you like, tomorrow I'm driving Mineral Mtn Road down the waterfall thru Florence Box Canyon with my dad, ambient temps are expected to be up to 100 degrees. I thought of using torque pro to graph the following to help me visualize the effects of my driving habits, terrain, etc:
Incline, RPM, speed, throttle position, gear, tc slippage, engine coolant temp, trans oil temp.
It would be interesting to compare notes with others on trans temp. I prefer manual transmissions, if mine goes out I'll look at installing a ZF6.
I thought of installing a large trans cooler like off a dodge truck or ExplorerTom's but I didn't have the additional funds to install electric fans. I might put a 16" pusher in front of the AC condenser. If the Hayden fails a large cooler may be next if I don't swap in a manual trans.
Jim
