Willard Norris

@Grumpy Bear @swathdiver UPDATE: thank y’all so much for all the help with everything. Over the past month I’ve done the following to my truck: -replaced cooling thermostat with the Mishimoto 180 design -installed new transmission cooling lines which now comes with a 70° C (158° F) transmission thermostat -had the radiator cooling fans checked…they work perfectly. Drove on a 4 hour and 5 hour drive with trans temps hovering around 172-175 during cruise, but would rise to mid 180s when sitting in traffic. -transmission shop that did the rebuild performed a hot flush and changed out the fluid as well. No metal was found during the flush. So….I think everything has been done that y’all recommended. The 180 thermostat seems to have been a big help, but I’ll keep monitoring things. Thank you again!!!

@swathdiver @Grumpy Bear I spoke with the transmission shop and they have 3 HotFlush machines in their shop. They flush each vehicle when they do a rebuild, but he said he’d do another flush and drop the filter if I’d like. - if my cooling fan isn’t working properly (going into high mode at the appropriate time), should I replace the fans before the fluid flush? If the cooler gets flushed and cleaned, but the fans fail to cool properly, then tranny temps while stopped may still run high. - as a shade tree mechanic, is there a way to re-tune the fans to go into high mode at a lower temp? If so, what would I need to get in order to do this? Thank you.

The transmission was rebuilt in November ‘22 and only has ~2,500 miles on it. I’ll be contacting the transmission shop again tomorrow. thank you.

@Grumpy Bear @swathdiver Update for 12 Apr: -I installed the Mishimoto 180 thermostat in the morning. -drove 98 miles up to north Georgia with outside air temp ~80°. -Engine temp stayed around 197 mark on analog gauge the entire time -Tranny temp hovered around 172 cruising 65-70 mph (see pic) -Tranny temp got to 183 in some city driving -conditions were the same for the drive home -Range AFM delete was not installed -Other than looking orange, tranny fluid has no metallic shavings that I can detect using a magnifying glass. Of course, that doesn’t preclude debris from being lodged inside the cooler/radiator So based on that limited information, do y’all still recommend that I 1. Try to find a shop with a hot flush machine 2. Install a new radiator if unable to find hot flush machine or 3. Drive as-is and monitor and just get fluid changed As y’all can tell, I’m mot a mechanic, but don’t mind trying to fix my own stuff if able, and I’d like to keep this truck for a while longer if I can get this figured out. Thx!!

@Grumpy Bear I checked the TBV this morning, and the Superior delete is installed correctly. Next I’ll contact the transmission shop and ask about flushing the lines and cooler. Also gonna get the Mishimoto VET-180 cooling thermostat as well to see if that provides any relief. There’s a Summit Racing place about 30 miles from here. Thx again. I’ll follow up with any updates.

Grumpy Bear (not sure how to flag your name) So based on the information I’ve given, you believe there’s likely some type of restriction in the lines or cooler, or the TBV is problematic, correct? I should be able to check the TBV this evening, and will contact the transmission shop tomorrow. Thank you.

These are the pics I made during my last long trip in March. 221° was when I came off the freeway to get gas. It rose pretty quickly to that temp. The 214° was a few days later at 70 mph after about 90 minutes of driving though Alabama….not too many hills.

I should also mention that the trans fluid has turned orange (see pic), and that’s with only 2,000 or so miles since the trans rebuild. It was nice and red after the rebuild. This discoloration seems to have occurred with my recent long drive in March with trans temps around 220°. Outside temperatures were less than 70° during the drive

Yes, I installed Superior delete last September, but am gonna verify that the trans shop didn’t change it out for some reason. I will also contact them to ensure the cooler and lines were flushed. Heaven only knows what that Range is doing in the background.

Does this particular thermostat need a re-tune? I don’t have the equipment for that. According to the transmission mechanic, my cooling fans will only go into high mode when using a scanner. He cannot figure that one out, but thinks that may be why trans temp runs high when in stop and go traffic, although this doesn’t explain the trans temp of 217 when cruising. Of course, that was before removing the Range AFM delete. After removal, cruise temp stayed at 178ish. I realize that may just be coincidental, but that Range also caused my truck to fail the emissions test, so there’s definitely stuff going on behind the scenes with that thing. I’m also gonna double check the trans thermostat to make sure the Superior Solutions internals are still in there. Last summer, I had actually “flipped the pill” before installing the Superior delete, and that didn’t seem to help either. Based on my understanding, the pill flip or superior delete should be doing basically the same thing. Also….I have an iPhone instead of an android.

Since my temp sensor was replaced, the engine stays pegged at 210° once it’s warm. If I were to change thermostats would I need to replace the sensor again?

I’ll call and ask about it. Did you install yourself? If so, how much of a pain was it?

I totally mistyped. It’s the 4.3 V6. My brain combined the two. I corrected the title.

Thx Mikey. I live in Georgia. We have hills, but they’re pretty mild. The Range AFM module may have nothing to do with the temperature. I’m throwing darts at this point. Where did you get the 194° cooling thermostat?

4.6 swap with what? I don’t understand your question.

2014 GMC Sierra 1500 4.3L Trans temp issue (6L80) 88k miles Feb 2022: installed Range AFM deactivator to prevent going into 4 cylinders Spring 2022: noticed transmission temperatures consistently going into the 200°+ range and increased shuddering while shifting. Highest temp was 237° Sep 2022: installed “Superior Solutions” thermostat, but temps didn’t really change Nov 2022: rebuilt transmission with new torque converter Nov 2022: first long drive, trans temp got to 205° in stop & go traffic Nov 2022: transmission shop re-checked everything, and trans was functioning properly, but cooling fans were not going into high mode except when he would force it into high mode with scanner Nov 2022: replaced temp sensor on cooling unit Mar 2023: first long drive since temp sensor replacement, and trans got to 217° after 2 hours of cruising with outside temps around 50°. — stopped and removed Range AFM deactivator. Trans temp settled around 178° during next 2 hours of driving except going in stop & go traffic: 186° under those conditions. Apr 2023: Returned to trans shop, and the specialist states cooling fan still doesn’t go into high mode. Thinks the computer is somehow preventing it from going into high mode 2 questions: Is it possible that the Range AFM deactivator was somehow causing high trans temps? Would resetting the computer possibly help the cooling fan to operate normally? If so, how do you do a reset? The fan will work on high mode only when forced by mechanic using a scanner, but not under normal operating conditions. I live in Georgia without too many steep hills. Any other recommendations?