Can you "flip the pill" on a 2014 4.3 Silverado?

Jayselectricco · January 12, 2023

Here is my issue... I have a 2014 Silverado 4.3 4x4 with 130k miles, I got one of those Range AFM disablers and it was working great with no issues. I was driving down the interstate the other day and seen my transmission temp up to 240. So I "flipped the pill," or reversed the transmission thermostat, and also replaced transmission fluid (by siphoning and refilling from dipstick tube). Right after that the same day I am driving I get some weird shifting, almost like the 2 stages in the torque converter isn't working, almost like its staying in 1 stage. It goes in limp mode and I get the codes p0741 and p0700... So... did my torque converter just go out with the new fluid? Or is my transmission filter clogged causing this? Is it something to do with flipping the pill? Is it the Range screwing with my TCM? What do you guys think? Thanks

rav3 · January 12, 2023

It's my opinion that changing the transmission fluid, especially the way you have from the top, will not mess-up your torque converter as many other say. I have been doing the ATF change for 30 years, even on a BMW X3 (w/GM transmission) with 132k miles & all looked very good & now has almost 200k on it. I also just pulled the pan to replace a leaky pan gasket on my '05 330iC with 109k miles yesterday, also a GM transmission, & the filter, fluid, magnet & pan still looked very good. Just an old hard seal.

See if you can clear the codes & see if they come back. I'm also curious, how did the old fluid look & smell?

Jayselectricco · January 12, 2023

2 minutes ago, rav3 said:

It's my opinion that changing the transmission fluid, especially the way you have from the top, will not mess-up your torque converter as many other say. I have been doing the ATF change for 30 years, even on a BMW X3 (w/GM transmission) with 132k miles & all looked very good & now has almost 200k on it. I also just pulled the pan to replace a leaky pan gasket on my '05 330iC with 109k miles yesterday, also a GM transmission, & the filter, fluid, magnet & pan still looked very good. Just an old hard seal.

See if you can clear the codes & see if they come back. I'm also curious, how did the old fluid look & smell?

The fluid was old and dark looking, didn't smell burnt but didn't smell too good either. I have heard that the 4.3 doesn't have the transmission cooler like the 5.3s do, and I wonder if turning the thermostat around has somehow caused this problem? I did clear the codes and drove it down the road and back, kind of seemed like from 3rd to 4th gear when it changes gears it revs back up to where it was before it shifted but did seem like it changed gears, and then going in to 5th and 6th was fine... I don't hear any noises or don't have any shuttering, and it feels like the transmission is shifting better except for that weird shift its doing.

rav3 · January 12, 2023

I would run it for a bit, say 500+ miles & change it again. I also like the LubeGuard ATF additive. I change my '17 5.3L 6 speed ATF fluid at 30k, then about every 10k-12k miles after that (or every 2nd oil change) the same way you do, sucking 4-5 qts out the dip stick fill tube. It's cheap insurance. I also did the pill flip & run the Range AFM Disabler. If you have the thermostat bypass device on the side of your transmission, it does circulate the ATF to the radiator for cooling. With the pill flip your transmission should run same temps as the earlier 4 speed GM transmission as far a temp goes, as they didn't have that device. It's been added to keep the fluid hotter, to make it thinner fluid for the EPA mileage stuff, same as the stupid AFM was added to increase EPA mileage mandated by the government. Good luck

newdude · January 12, 2023

3 hours ago, Jayselectricco said:

Here is my issue... I have a 2014 Silverado 4.3 4x4 with 130k miles, I got one of those Range AFM disablers and it was working great with no issues. I was driving down the interstate the other day and seen my transmission temp up to 240. So I "flipped the pill," or reversed the transmission thermostat, and also replaced transmission fluid (by siphoning and refilling from dipstick tube). Right after that the same day I am driving I get some weird shifting, almost like the 2 stages in the torque converter isn't working, almost like its staying in 1 stage. It goes in limp mode and I get the codes p0741 and p0700... So... did my torque converter just go out with the new fluid? Or is my transmission filter clogged causing this? Is it something to do with flipping the pill? Is it the Range screwing with my TCM? What do you guys think? Thanks

P0741 = you need a converter. Those temps were probably a sign it was going.

Range didn't cause it. Nor did the pill flip.

Jayselectricco · January 12, 2023

3 minutes ago, newdude said:

P0741 = you need a converter. Those temps were probably a sign it was going.

Range didn't cause it. Nor did the pill flip.

So your saying that the fluid change probably washed away the gunk that was keeping it functional? Do you think its possible that the filter could be clogged up? I guess I could drop the pan and see if there is any metal in there. If there is no metal could the converter still be bad? Thanks

Jayselectricco · January 12, 2023

Thank you! Yeah it is crazy to have a transmission thermostat in my opinion, and then not have the high temp warning come on until 260 something... if that thermostat starts sticking it will cook peoples transmissions before they even know they have a problem.

newdude · January 12, 2023

13 minutes ago, Jayselectricco said:

So your saying that the fluid change probably washed away the gunk that was keeping it functional? Do you think its possible that the filter could be clogged up? I guess I could drop the pan and see if there is any metal in there. If there is no metal could the converter still be bad? Thanks

Its possible. The design of the converter is the real issue at the end of the day. Drop the pan and check the magnet. If it was 240F for a long time, I'd be concerned about further damages to other clutches as well. Also, if the converter was bad enough, likely has put damage to the pump as well.

Jayselectricco · January 12, 2023

6 minutes ago, newdude said:

Its possible. The design of the converter is the real issue at the end of the day. Drop the pan and check the magnet. If it was 240F for a long time, I'd be concerned about further damages to other clutches as well. Also, if the converter was bad enough, likely has put damage to the pump as well.

Ok thanks, I will drop the pan and check it out.

Grumpy Bear · January 12, 2023

6 Causes of P0700 Code on Chevy Silverado (Fixes Included) - MechanicHope

Jayselectricco · January 13, 2023

14 hours ago, Grumpy Bear said:

6 Causes of P0700 Code on Chevy Silverado (Fixes Included) - MechanicHope

So you have the 4.3? What do your transmission temperatures normally run?

Grumpy Bear · January 13, 2023

6 hours ago, Jayselectricco said:

So you have the 4.3? What do your transmission temperatures normally run?

Now? It's rare to see it over 160 F unless I am sitting dead in traffic. Down the road at 62 mph 138/148 F dead of winter and 148/165F heat of summer. Nothern Ilinois. -25F to 100F is our range. I'm currently using the new GM thermostat. Changed last fall. The 2014 and early 2015's have a different line connection but the 'guts' will interchange.

Or flip. I ran that for a long time with slightly cooler results in the winter but nothing worrisome. I also run a colder water thermostat and this matters because OUR trans cooler is the right-side tank of the radiator. Cold side. Here' is some data I've collected over the last 7+ years. The yellow is the new GM TBV and the other two with a pill flip and noted water thermostat. Not plotted is factory with factor water stat. Ran about 25F warmer across the board. Saw 240F a few times flogging on her on hot days.

Hope that is useful.

Jayselectricco · January 13, 2023

Thanks for the info, that will be very useful.

Jayselectricco · February 9, 2023

Ok so I am just getting around to dropping the pan, I haven't been driving it. There is no metal whatsoever or anything shinny in the pan or on the magnet, just some sludgy looking stuff on the magnet. So is this a sign that the transmission and converter may still be good? I am changing the filters and fluid with AC delco fluid, and putting in one of those surecool thermal bypass and going to see what happens.

steelerdude15 · February 9, 2023

13 minutes ago, Jayselectricco said:

Ok so I am just getting around to dropping the pan, I haven't been driving it. There is no metal whatsoever or anything shinny in the pan or on the magnet, just some sludgy looking stuff on the magnet. So is this a sign that the transmission and converter may still be good? I am changing the filters and fluid with AC delco fluid, and putting in one of those surecool thermal bypass and going to see what happens.

Yup, sounds like everything is still good to me.