Im sorry, but it is kind of funny GM 21-NA-199

BlaineBug · December 5, 2021

On 11/22/2021 at 6:28 PM, 14burrito said:

So I'm led even more so believe that the 180 marked on the OE stat is start to open when stats have historically been about 15 or so start to full (194 -15 = 179).

The stamped 70 reverses this role obviously as 70c = 158f.

You can disassemble the new housing and reporting what's stamped on the stat, disassembly is extremely easy.

Iv been a believer that the thermostat is labeled start to open temps.

I got a chance to install this revised cooler bypass/thermostat today. I disassembled both the new and the old. The OLD pill is labeled V180 while the NEW pill is labeled V135.

BlaineBug · December 5, 2021

1 minute ago, BlaineBug said:

I got a chance to install this revised cooler bypass/thermostat today. I disassembled both the new and the old. The OLD pill is labeled V180 while the NEW pill is labeled V135.

If you're theory is correct that means that the new thermostat starts opening at 135'F and is fully opened at 158'F.

14burrito · December 6, 2021

5 hours ago, BlaineBug said:

I got a chance to install this revised cooler bypass/thermostat today. I disassembled both the new and the old. The OLD pill is labeled V180 while the NEW pill is labeled V135.

Thank you for checking and confirming this, the more we know!

BlaineBug · December 6, 2021

No problem.

16LT4 · December 6, 2021

On 12/3/2021 at 2:01 PM, BlaineBug said:

I haven't had a chance to install my lower temperature "revised" transmission thermostat yet, however I can't see how you'd experience both lower operating temperature and faster warm up simultaneously. Your trans fluid is being exposed to the same ~210 degree engine coolant either way.

Regardless, someone above asked if I could detail what my operating temps are with the old style thermostat. I just returned from a 90-120 minute trip in city traffic non-highway. When returning home the cluster read the transmission temperature at 189 degrees. Engine coolant temp reading centered at approximately ~210 degrees. The outdoor ambient temperature is currently at 51 degrees.

To my understanding, the AT thermostat as originally designed is closed until the transmission reaches its operating temperature, so the ATF isn't being exposed to 210*F coolant until the ATF reaches high temperatures, opening the flow through its thermostat; ECT increases faster than transmission temperature. Coolers are often heaters when said cooler is liquid-liquid; the oil cooler on my BMW acts as an oil heater on a cold start, because ECT also increases faster than oil temperature. ECT doesn't reach 200* for at least 10 minutes, sometimes 15, during the cold season right now, so the trans fluid isn't being exposed to 210* coolant until the coolant itself warms. Regardless, one doesn't need to fully understand the "how," when the data and numbers don't lie. My ATF is hotter by the time I get to work (12 miles each way) now than before I "flipped the pill", so here an unforeseen result of flipping the pill seems to allow the truck to spend more time driving with hot fluid than cold. One can read and consult google, but the best data is what is personally collected.

Even towing a car 200 miles back in August, my AT fluid never got hotter than 165*, even in stop-and-go. Before the pill flip, I'd see temperatures in the mid 190*s, unladen on the highway.

newdude · December 6, 2021

On 12/1/2021 at 4:46 PM, Epsilon Plus said:

This is what my 2022 6L90E stat looks like on my 11/21 built 2500 HD. The 70 stamp and all.

I saw somewhere back that the HDs didn't used to have a stat.

Guess what...

Correct. HD has had a stat since the 2020 T1 new trucks came out. Prior to that 2019 and older gas have never had one. 2017-2019 diesel did however. Was mounted on the aux cooler lines. 2016 and prior diesels did not have one.

Edited December 6, 2021 by newdude

newdude · December 6, 2021

On 12/3/2021 at 2:01 PM, BlaineBug said:

Your trans fluid is being exposed to the same ~210 degree engine coolant either way.

Quick tip for everyone in this thread.

2014 and early 2015 V8 trucks, yes, this is correct. The trans cooler lines hit the radiator, then go out to the aux cooler at the top of the condenser.

However...

This is NOT the case late 2015-2019 old body V8. They no longer touch the main radiator at all. They are dedicated flow to the cooler at the top of the condenser.

See pics below. I added some red lines in case the lines GM drew weren't 100% clear connecting the lines to their proper fittings/other lines. Again, V8 only, the V6 doesn't have an aux cooler and only flows through the radiator.

Grumpy Bear · December 7, 2021

2015 V6 is radiator only and the fluid enters the passenger side bottom (opposite that of the V8) and leaves the radiator on the passenger side top. Can't say about other years.

Like 16LT4, ATF fluid heat up is much quicker with pill flipped. Does not get as hot but does get to say 125 F much quicker.

Aftermarket thermostats have a minimum flow to the cooler. Normally about 10% of the pump output to the cooler. The factory thermostat allows zero flow to the cooler bypassing 100% back to the transmission. This robs the system of the quick heat up that aftermarket thermostats permit.

BlaineBug · December 7, 2021

15 minutes ago, Grumpy Bear said:

2015 V6 is radiator only and the fluid enters the passenger side bottom (opposite that of the V8) and leaves the radiator on the passenger side top. Can't say about other years.

Like 16LT4, ATF fluid heat up is much quicker with pill flipped. Does not get as hot but does get to say 125 F much quicker.

Aftermarket thermostats have a minimum flow to the cooler. Normally about 10% of the pump output to the cooler. The factory thermostat allows zero flow to the cooler bypassing 100% back to the transmission. This robs the system of the quick heat up that aftermarket thermostats permit.

Where is the heat coming from if not connected to the radiator for a fluid to fluid heat transfer mechanism? I know these trucks run the A/C if in "auto" mode on the climate controls so the condenser would be my only theory, since the condenser does get hot in normal A/C mode.

Grumpy Bear · December 7, 2021

10 hours ago, BlaineBug said:

Where is the heat coming from if not connected to the radiator for a fluid to fluid heat transfer mechanism? I know these trucks run the A/C if in "auto" mode on the climate controls so the condenser would be my only theory, since the condenser does get hot in normal A/C mode.

Isn't. This would only be true for the models that use the radiator as the primary and best on models where the radiator is the only cooler/heater.

I expect this works like it always has. GM tries something awful. Owners manage a work around. GM defeats the work around...Rinse and repeat.

Harley does a similar thing. Aftermarket comes up with a problem solver then Harley mimics it and makes it part of a package forcing the aftermarket to a different product and/or living with the sales possible from earlier models.

Actually...they all do it. It's what passes for Research and Development these days.

A person so inclined might look at an early radiator for the 2016 on models. And if the coolers are already present and just not being used re-piping the system to the early layout. There are a few aftermarket radiators so equipped.

Providing of course you see value in a quicker warmup.

I believe the systems without radiator cooler, are they not also the models with shutters?

16LT4 · December 7, 2021

11 hours ago, BlaineBug said:

Where is the heat coming from if not connected to the radiator for a fluid to fluid heat transfer mechanism? I know these trucks run the A/C if in "auto" mode on the climate controls so the condenser would be my only theory, since the condenser does get hot in normal A/C mode.

The ATF cooler lines are still ran through the engine compartment, which are increasingly well sealed to ambient air, so my untested hypothesis is that the lines, and therefore the fluid flowing through them, is heated by radiant heat soak from the engine. Yesterday, ambient temperature of 58*F, my ATF was at 90*F within 5 minutes of run time and less than a mile. With the ATF t-stat working as designed, I'd be almost home (12 miles) before hitting that temperature IIRC.

I don't have shutters.

Edited December 7, 2021 by 16LT4

14burrito · December 7, 2021

4 hours ago, Grumpy Bear said:

Isn't. This would only be true for the models that use the radiator as the primary and best on models where the radiator is the only cooler/heater.

I expect this works like it always has. GM tries something awful. Owners manage a work around. GM defeats the work around...Rinse and repeat.

Harley does a similar thing. Aftermarket comes up with a problem solver then Harley mimics it and makes it part of a package forcing the aftermarket to a different product and/or living with the sales possible from earlier models.

Actually...they all do it. It's what passes for Research and Development these days.

A person so inclined might look at an early radiator for the 2016 on models. And if the coolers are already present and just not being used re-piping the system to the early layout. There are a few aftermarket radiators so equipped.

Providing of course you see value in a quicker warmup.

I believe the systems without radiator cooler, are they not also the models with shutters?

My condenser cooled ATF is built with shutters.

BlaineBug · December 7, 2021

6 hours ago, Grumpy Bear said:

Isn't. This would only be true for the models that use the radiator as the primary and best on models where the radiator is the only cooler/heater.

I expect this works like it always has. GM tries something awful. Owners manage a work around. GM defeats the work around...Rinse and repeat.

Harley does a similar thing. Aftermarket comes up with a problem solver then Harley mimics it and makes it part of a package forcing the aftermarket to a different product and/or living with the sales possible from earlier models.

Actually...they all do it. It's what passes for Research and Development these days.

A person so inclined might look at an early radiator for the 2016 on models. And if the coolers are already present and just not being used re-piping the system to the early layout. There are a few aftermarket radiators so equipped.

Providing of course you see value in a quicker warmup.

I believe the systems without radiator cooler, are they not also the models with shutters?

The AC condenser does get warm, as heat in the cab is taken out.

BlaineBug · December 8, 2021

3 hours ago, BlaineBug said:

The AC condenser does get warm, as heat in the cab is taken out.

So if it's getting warm that will also impact trans temperature. On any day even a hot day I don't see under hood temperatures having a significant impact on the trans cooler lines that run through there to the front of the vehicle.

16LT4 · December 8, 2021

12 hours ago, BlaineBug said:

So if it's getting warm that will also impact trans temperature. On any day even a hot day I don't see under hood temperatures having a significant impact on the trans cooler lines that run through there to the front of the vehicle.

Maybe maybe not, but heat soak is the best explanation I've come up with. Also, don't discount heat soak; if under-hood engine air can cost an engine 20-30 hp (based on fuel trims and trap speeds from engineer friends who log this sort of thing for fun), it will certainly help heat anything in the engine bay. Even in sub-zero ambient temperatures, snow/ice melts off my insulated hood surfaces within a few miles/minutes, so heat-soak is definitely a factor.

Here's some information I obtained on another one of my vehicles to compare intake temperatures with and without the factory "cold air" intake snorkel installed, taking note of IAT (which is closely equivalent to engine-room air temp, of 100*F):

On the same loop, in the same direction every time, at the same range of speeds 30-65 mph. Some N52 E83 data from today:

Ambient air temp: 27.5*C

After 5 mile drive to get to operating temp as per ECT: IAT 29.5*C.

I stopped, removed the intake snorkel elbow from the air inlet to the air box. IAT shot up to 33.5*C within a few hundred yards. By the end of the loop, IAT hit a max of 38.2*C, dropping back to 37.2*C when I slowed down to a stop at the starting line.

Back to starting point. Re-installed the elbow. IAT dropped to 33.4 within 100ft, and ranged 31.5-33.5*C while driving.

Some interesting points. Regardless of whether the intake elbow was in place, idle temp after both loops was the same 36.5-37.5*C.

With the elbow OFF, 65 mph showed a 2*C WARMER IAT than at 35-40 mph. Under full throttle acceleration, where one wants power, IAT reached 39.5*C; if I sustained throttle position even longer, I would fully expect even hotter IAT.

With the elbow on, however, full throttle application saw the reverse. From 33*C at cruise at 45mph, I could instantly drop IAT to 29*C with my right foot, and then watch IAT more slowly raise back to its starting position once the throttle pedal was released. As long as I maintained the call for power with my right foot, IAT remained close to ambient air temp, unlike elbow off. Elbow On showed a smaller IAT temp delta at all speeds, only 2-3*C range compared to about 5*C, with the range occurring closer to ambient temp.

Elbow on IAT stayed within 10*C of ambient air temp at low-load conditions with only a 2*C delta at higher load conditions, while elbow off showed a minimum of 10*C and 12*C, respectively.

The divergent IAT data implies a few things: 1) under-hood airflow/air temp equalization is virtually nonexistent on this chassis and has no affect on IAT. If it did, IAT and vehicle velocity would have inverse relationships regardless of elbow installation. 2) further support that the factory air intake truly is a “cold air intake”, as lifting those valves higher and opening the throttle butterfly increase cold air velocity, combatting engine heat soak on the air intake tubes. The same speed-dependent elbow-on IAT data from above was replicated at a constant speed of 35 mph by downshifting into lower gears, increase engine RPM and intake air velocity, attempting to remove airflow as a variable.