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

Grumpy Bear · March 12, 2022

New Transmission Thermostat Data Update

Turns out not so much a floor as support.

Gray bubbles are the new valve which I labeled by the cracking temperature.

I expect most drive faster than I do and that will raise the slope below 138 F. I also run a finned 8 quart sump. Factor that as well. Although I don't have any data yet above 55 F I already know from previous work that my much colder water thermostat and the fact I have only the radiator cooler that hotter water stats will give higher ATF readings as well. So treat this as directionally useful and not some absolute gospel.

Edited March 23, 2022 by Grumpy Bear

cs15dah · March 22, 2022

On 1/17/2022 at 8:16 AM, 16LT4 said:

A word of caution for anyone installing the new thermostat: mine, from GMpartsdirect, did NOT come with the o-rings for the ATF cooler lines, so I needed to transfer them from the old thermostat. Carefully inspect your new one to verify o-ring existence.

On 1/17/2022 at 11:30 AM, mikeyk101 said:

No, o-rings definitely do not come with the new one.

...

So I agree and can't stress this "little" detail enough, make sure the o-rings are still on the 2 cooling lines before fitting into the new thermostat.

Can you just buy new o-rings, when placing your order for the new TBV? Is 23135703 the part number for the o-rings?

My lines (23370657) are leaking up front where they go from rubber to metal. So I'll be ordering new lines as well as the new TBV. Appears the new lines does come with the o-rings on the (old) TBV, so I'll be able to swap them out before installing.

Do you think eventually the lines will just come with the 70c thermostat already installed?

Edited March 22, 2022 by cs15dah

cs15dah · March 22, 2022

16 hours ago, cs15dah said:

Do you think eventually the lines will just come with the 70c thermostat already installed?

Looks like I just answered my own question. My transmission cooler lines (23370657) came in today. The attached TBV does indeed have 70 marked on the bottom.

cs15dah · March 23, 2022

Installed tonight. Since I was in there already, replaced 4.5 qts of Dexron VI. Got to use my new Mityvac MV7400. Holy smokes, why didn’t I buy one of these decades ago?! Sure made the fluid swap a whole heck of a lot easier. And cleaner!

scralatchtica824 · March 23, 2022

14 hours ago, cs15dah said:

Installed tonight. Since I was in there already, replaced 4.5 qts of Dexron VI. Got to use my new Mityvac MV7400. Holy smokes, why didn’t I buy one of these decades ago?! Sure made the fluid swap a whole heck of a lot easier. And cleaner!

Where'd you purchase your Mityvac MV7400 from? Amazon?

Did you need any any additional hosing to get it all the way down into the pan?

I'm going to do a flush soon at 25k on my 2018 are you all using the standard GM fluid or something else?

I've had the updated thermostat for about 2 months now.

It usually settles at 142-144F for local and around town/short highway trips. It was 80 degree's and sunny a few weekends ago and I was doing 80-85mph on the interstate through some pretty good sized WV/OH hills with a dirtbike in the bed and the highest it hit was 167F. Normally, with the stock thermostat, it would get to then stay at 190F no matter what the outside ambient temperature was.

Edited March 23, 2022 by scralatchtica824

14burrito · March 23, 2022

Mityvac FTW, bought mine off ebay.

Comes with hoses that work for the ATF fluid exchange.

Edited March 23, 2022 by 14burrito

cs15dah · March 23, 2022

37 minutes ago, scralatchtica824 said:

Where'd you purchase your Mityvac MV7400 from? Amazon?

Did you need any any additional hosing to get it all the way down into the pan?

I'm going to do a flush soon at 25k on my 2018 are you all using the standard GM fluid or something else?

I've had the updated thermostat for about 2 months now.

It usually settles at 142-144F for local and around town/short highway trips. It was 80 degree's and sunny a few weekends ago and I was doing 80-85mph on the interstate through some pretty good sized WV/OH hills with a dirtbike in the bed and the highest it hit was 167F. Normally, with the stock thermostat, it would get to then stay at 190F no matter what the outside ambient temperature was.

Yes, I bought mine from Amazon. No additional tubes needed. There are two dipstick tubes different diameters, then a main suction tube. I connected the larger of the two dipstick tubes together with the main suction tube, which should be about 10 ft in total. Plenty of length to stick down into the trans pan with the main reservoir sitting on the ground next to the front tire. Prior to sliding the tube in, I compared the length of tube side-by-side with the dipstick, so I'd know what depth I was trying to hit. Then slid it in up to that mark, and then an inch or two more until I felt a bit of resistance, which I think is just the tube bottoming out at the bottom of the trans pan. Pumped it up, and it worked beautifully. I can't believe I haven't bought one of these before! Especially since I like to do the drain & fill three times to get the most fresh fluid into the transmission.

I used GM Dexron VI this time. Last time, 53,130 miles ago I used Valvoline MaxLife. I don't have specific brands I stick to. Usually just the best price on a quality lubricant. 166K miles so far on my 2015 Suburban and no issues whatsoever. I use Mopar fluids on my Ram 2500, nothing fancy, and I got 386K on the transmission before it needed a rebuild. 443K on it now and still going strong.

Yesterday on a cool 68F night, I took a 40 mile drive at 60 MPH and the average trans fluid temp was 176F. Got into town where it was 25-30 MPH with stop and gos and I saw it reach a max of 186F. Prior to this new TBV, I'd usually see around 196F, with stop and gos getting into 200-209F.

cs15dah · March 23, 2022

26 minutes ago, 14burrito said:

Mityvac FTW, bought mine off ebay.

Comes with hoses that work for the ATF.

With the Mityvac, how'd you get that spill??

14burrito · March 23, 2022

1 hour ago, cs15dah said:

With the Mityvac, how'd you get that spill??

Wasn't an oil spill, I got sloppy cleaning the mityvac. Cleaned the container prior to pulling the fluid so I could get a clean sample to send out.

steelerdude15 · March 24, 2022

Harbor Freight also sells a fluid extractor just like the one mentioned above.

F4Gary · March 24, 2022

On 2/24/2022 at 1:45 AM, palmer_df0130 said:

Does anybody know if the new tbv internals will swap out with the old tbv with the quick disconnect cooler lines? I have a 2014 Silverado and do not want to have to buy new cooler lines along with the new valve to make it work. Thanks.

On 2/24/2022 at 8:04 AM, Grumpy Bear said:

Yes they will! And will swap into the 8L and 10L TVB's as well.

So this begs the question, why can't we just buy the internals as a kit and not the whole thing?

I just learned of this pill flip thing and am going to try it. Maybe later I will spring for the newer part and just swap the internals.

cs15dah · March 24, 2022

On 3/23/2022 at 1:54 PM, 14burrito said:

…so I could get a clean sample to send out.

I'm sending in a sample too. This’ll be the first time for trans fluid in my Suburban. I usually only do the oil.

cs15dah · March 24, 2022

1 hour ago, F4Gary said:

So this begs the question, why can't we just buy the internals as a kit and not the whole thing?

I just learned of this pill flip thing and am going to try it. Maybe later I will spring for the newer part and just swap the internals.

Isn’t that one of the main reasons why this thread started? The OP buying just the internals, in the form of the Katech 17, and installing into his existing TBV? But I get it. You’re specifically asking about OEM GM internals.

The pill flip is free. So yeah, I see why folks tend to want to do that. But for less than the cost of a tank of fuel, one could buy the new 70c TBV. I see they’re available on eBay for $50-80, shipped. GM Parts Giant about the same price; maybe just a bit more. My opinion, I’d only want to do the job once. Not that it’s hard. I’m just lazy. So I’d rather spend the $50+ up front and do the job just once. Just my recommendation, if you plan on doing the new TBV down the road anyways.

Has anyone done the pill flip, or the Katech 17, with the TBV still on the truck? I can’t imagine it being done without a lot of difficulty. So if you’re having to take the TBV off the truck anyways, may be less work to just swap in the new TBV.

Sheesh. Reading the above it looks like I make commission off of TBV sales! Not really trying to sway your decision. Really just saying it may not be worth doing the free mod now, if you’re just going to do the $50+ mod later anyways.

14burrito · March 25, 2022

18 hours ago, cs15dah said:

I'm sending in a sample too. This’ll be the first time for trans fluid in my Suburban. I usually only do the oil.

My sample came back good, so much so Blackstone questioned the mileage on it. Makes me wonder if the previous owner did a trans service or not.

I dont think the pill flip can be done on the vehicle due to location. Been a while since I was under the Tahoe, but from the picture posted above, top of it's kind of close to the body. The internals are removed via the top, not the bottom. Trying to get the circlip off would be tedious I believe.

You mentioned Katech 17 above, what are you referencing? The Katech 174 is an engine thermostat, not ATF circuit related. I only brought that up in the OP because of, what I perceive, these Tahoe's run warm. I live in AZ and I had some high ECTs just driving around town, not a fan of their cooling strategy. I brought up my concerns directly with the dealer(s) and GM corporate and we were told by the Engineering Department, my concerns were not valid and the Powertrain was operating within the designed temps....and then a year later GM released their TB for a lower temp trans tstat...

Edited March 25, 2022 by 14burrito

F4Gary · March 25, 2022

19 hours ago, cs15dah said:

Isn’t that one of the main reasons why this thread started? The OP buying just the internals, in the form of the Katech 17, and installing into his existing TBV? But I get it. You’re specifically asking about OEM GM internals.

The pill flip is free. So yeah, I see why folks tend to want to do that. But for less than the cost of a tank of fuel, one could buy the new 70c TBV. I see they’re available on eBay for $50-80, shipped. GM Parts Giant about the same price; maybe just a bit more. My opinion, I’d only want to do the job once. Not that it’s hard. I’m just lazy. So I’d rather spend the $50+ up front and do the job just once. Just my recommendation, if you plan on doing the new TBV down the road anyways.

Has anyone done the pill flip, or the Katech 17, with the TBV still on the truck? I can’t imagine it being done without a lot of difficulty. So if you’re having to take the TBV off the truck anyways, may be less work to just swap in the new TBV.

Sheesh. Reading the above it looks like I make commission off of TBV sales! Not really trying to sway your decision. Really just saying it may not be worth doing the free mod now, if you’re just going to do the $50+ mod later anyways.

The replacement TBV won't work on my '14. Not the right tube connections. So I'd have to swap out the guts and throw the aluminum housing away. Makes no sense when for 1/2 the price of a tank of gas I could just buy the guts in a kit and convert my existing TBV. It is a waste of money and materials...