Jump to content

Transmission temperature

Ahmad Alfilchawi
 Share

Recommended Posts

Ahmad Alfilchawi Enthusiast

Ahmad Alfilchawi

Posted
Posted

Hello guy I got 2015 Chevy Silverado 4x4 5.3L single cab short bed. I have done few mods which is (afe intake- jets throttle body - tune). usually in the weekend me and my friends go for off roading trips, and I am facing a trouble with the transmission temperature it could reach to 221F usually what I do, i open the hood and the AC for couple of minutes till it goes down. What I want to ask that I just have to delete the transmission thermostat or install transmission cooler, or the last option is to do both of them.

Grumpy Bear Senior Enthusiast

Grumpy Bear

Posted
Posted (edited)
7 hours ago, Ahmad Alfilchawi said:

Hello guy I got 2015 Chevy Silverado 4x4 5.3L single cab short bed. I have done few mods which is (afe intake- jets throttle body - tune). usually in the weekend me and my friends go for off roading trips, and I am facing a trouble with the transmission temperature it could reach to 221F usually what I do, i open the hood and the AC for couple of minutes till it goes down. What I want to ask that I just have to delete the transmission thermostat or install transmission cooler, or the last option is to do both of them.

Depends on your speed and your water thermostat/fan settings. The delete is easy, quick and cheap. Do that first and test. Then revaluate. I did the delete and at highway speeds it takes a really hot day to break 165F. Sitting dead in traffic like at an accident it can get about 210 F. That said a cooler without a thermostatic fan won't help much at crawling speeds. (off road) 

Edited by Grumpy Bear
  • Like 1
UofAZCats Enthusiast

UofAZCats

Posted
Posted
8 minutes ago, Grumpy Bear said:

Depends on your speed and your water thermostat/fan settings. The delete is easy, quick and cheap. Do that first and test. Then revaluate. I did the delete and at highway speeds it takes a really hot day to break 165F. Sitting dead in traffic like at an accident it can get about 210 F. That said a cooler without a thermostatic fan won't help much at crawling speeds. (off road) 

Not that familiar with the intricacies of transmissions, but if you can delete the transmission thermostat then why did GM include it?  What is its purpose?  I would think its job is to keep the the tranny cool but that seems to be the opposite of what it does.  Just trying to learn about this so any info is appreciated.

rbrjr1 Enthusiast

rbrjr1

Posted
Posted

everything that heats up and cools down has an optimal operating temperature (even our own bodies)..

 

Tstats are used to prevent crazy swings in operating temperature or to maintain a specific range.

Grumpy Bear Senior Enthusiast

Grumpy Bear

Posted
Posted
12 hours ago, UofAZCats said:

Not that familiar with the intricacies of transmissions, but if you can delete the transmission thermostat then why did GM include it?  What is its purpose?  I would think its job is to keep the the tranny cool but that seems to be the opposite of what it does.  Just trying to learn about this so any info is appreciated.

 

10 hours ago, davester said:

It's likely to get the transmission up to it's operating temperature faster.

 

1 hour ago, rbrjr1 said:

everything that heats up and cools down has an optimal operating temperature (even our own bodies)..

 

Tstats are used to prevent crazy swings in operating temperature or to maintain a specific range.

1.) Why indeed! Because viscosity is temperature dependent. Because viscosity is a measurement of a fluids internal resistance to flow. Because lower resistance means less parasitic fuel waste. Because the manufactures are driven by law to seek additional gains in fuel efficiency. That's the why. 

 

2.) What they are suppose to do is MAINTAIN a target temperature. IN this case about 192 F. The transmissions cooler, which is in the radiator as it has been for a very long time without a thermostat; actually functions as a heater at first as the water temperature rises more quickly than the transmission fluid temperature. Once fluid temperature rises (load driven) higher than the water temperature then is becomes a cooler. Hold that thought. 

 

The OEM thermostat does NOT have a minimum flow bypass and because is does not the transmission actually takes LONGER to come to heat than if it had no thermostat at all. Now put that thought with one your holding and you will see the flaw in the idea of a more rapid heat up. 

 

3.) Unlike the human body whose operation indeed is enhanced by finite temperature control of a few degrees the transmission has a much wider tolerance. MUCH wider. Functionally it is happy as a clam between a bit over 100F fluid temperature. Actually colder but the computer sets some limits on fuel and spark that are fluid temperature dependent. It continues happy until it gets too warm to afford the device adequate protection. Varnish starts to form around 220 F. Yes even with PAO lubricants 

 

Most major transmission parts suppliers and builders will tell you to keep the fluid under 180 F for longest life. GM's goals for your gearbox do not include you. They are CAFE driven. 

 

Chew of this. The transmission thermostat hasn't a minimum flow bypass. Has a set temperature of 192 F. The cooler is in the radiator HOT SIDE tank if you have a V8 and that thermostat is 207 F. :wtf:

 

 

 

  • Like 2
  • 2 years later...
GENE SEWELL New Member

GENE SEWELL

Posted
Posted
On 1/5/2020 at 1:11 PM, Ahmad Alfilchawi said:

Hello guy I got 2015 Chevy Silverado 4x4 5.3L single cab short bed. I have done few mods which is (afe intake- jets throttle body - tune). usually in the weekend me and my friends go for off roading trips, and I am facing a trouble with the transmission temperature it could reach to 221F usually what I do, i open the hood and the AC for couple of minutes till it goes down. What I want to ask that I just have to delete the transmission thermostat or install transmission cooler, or the last option is to do both of them.

global transmission part#STL010  .REPLACES THE GUTS OF THE TRANSMISSION BY PASSvalve - COOLER . 2014 and up works awsome there is a you tube video you can watch . .around 50.00  us .better than the original thermostat .

  • Thanks 1
CajunFries Enthusiast

CajunFries

Posted
Posted

Do the thermostat flip mod. You can look up the video on YT. It’s free and it’s just like a delete. If you’re not happy with that, get a Trucool 40K…. I never had the trans temp go above 160-165…. (I have my trucool for sale btw) 

pokismoki Senior Enthusiast

pokismoki

Posted
Posted

depending on your abilities, you might want to install a pipe plug between the crossover point on the hot and cold side of the cooler adapter, , i think its better than the flip trick because of less fluid blockage created by the thermostat when flipped,  either way works. pipe plug is  $12 for plug and a tap, flip trick is free, or aftermarket delete kit whith the added anti-drain check ball is about $65

  • Like 1
  • 4 weeks later...
Gandalf Enthusiast

Gandalf

Posted
Posted (edited)

GM quietly admitted their mistake with the original automatic transmission by-pass valve (thermostat) in 2014-2018 gas trucks. A while back, they replaced the part we all have from the factory, and replaced it with a part that looks identical, but that opens to send fluid to the cooler at a much lower temperature (158F, I think). 
 

I did try the “flip the pill” method, which was dead easy, but in my haste to complete the job, I neglected to press the c-clip into its channel fully. Ended up with a few litres of ATF coating my garage floor! In my fury at myself for missing such a simple thing, I got more angry at GM. So, I googled a bit and found the new part (86774933), which my local dealer had in stock. 

 

For the cost of a $100 (in Canada, everything costs more) part and minor effort to install, the truck now operates at safe temperatures all the time. Before, the ATF heated to around 195-210 just driving to work (half hour on hilly roads). With the new by-pass, it never gets above 150-155, even during a recent 8-hour drive through mountain passes here in northern BC, fully loaded and - because of 35 inch tires - constantly gearing down early on even small hills, not to mention the many 1-6 km long hills. It only reached 166 a few times, after sitting while I got gas or food. 

This is the only transmission mod I have, so those lower temperatures are all with just the factory in-radiator transmission cooler, and while driving at the hottest time of year - averaged 90-100 F. I thought I might require a good aftermarket cooler, and was about to order the Mishimoto one, but it’s overkill for now. 

 

As any ATF fluid temp/tranny longevity chart shows, fluid this cool prolongs the life of the transmission by app. 40,000 miles. So far, the best thing I’ve done to the truck (2015 AT new to me in March this year). 

Edited by Gandalf
  • Like 1
  • Thanks 1
Grumpy Bear Senior Enthusiast

Grumpy Bear

Posted
Posted

What does 70C mean?

 

70 C (158F)

158 F is the 'fully open' temperature.

148 F is the 'throttling' temperature.

138 F is the 'cracking temperature. 

 

 

[larger graph in post above].

image.thumb.png.9563ad229b6dd36a54702567d0251192.png

 

IF it won't stay in the 'throttling' range then more cooler is required to keep it there.

Not required if it stays under 180 F in your world of operation; just a physical fact. 

  • Like 1
Gandalf Enthusiast

Gandalf

Posted
Posted
7 hours ago, Grumpy Bear said:

What does 70C mean?

 

70 C (158F)

158 F is the 'fully open' temperature.

148 F is the 'throttling' temperature.

138 F is the 'cracking temperature. 

 

 

[larger graph in post above].

image.thumb.png.9563ad229b6dd36a54702567d0251192.png

 

IF it won't stay in the 'throttling' range then more cooler is required to keep it there.

Not required if it stays under 180 F in your world of operation; just a physical fact. 

Thanks for this. As I alluded in my comment, I am a bit concerned about winter. Even though where I live is mild, we still get below-freezing temperatures fairly regularly. 
 

Embarrassingly, the automatic transmission is the one I know the least about - even though my father was an AT specialist (for Ford, but . . . ). He was so busy when I was growing up, taking on side jobs rebuilding transmissions, he didn’t have time to teach much. So, I don’t know how - or even if - ATF can be too cool for the good of the trans. 
 

For now, I’m just happy with the results of just replacing a single part - I bored my family last week while on the road trip: I kept pointing at the DIC transmission temperature, amazed that it was 65C, not the usual 88-92C. 
 

I had a good transmission cooler as my next job for the truck, but I’m thinking I’ll hold off until winter, just to be sure the fluid does not remain too cool on sub-zero days. I also plan to drive up North in January, to an area that stays under zero all winter, often down into -30C or lower. So, I will definitely have a good idea how to proceed with the trans cooler or not.

 

I am also adding the B&M Hi-Tek deep trans pan this week, which adds 3 quarts to the fluid capacity. I’m not completely sold on that - I think their claims of the efficacy of added fluid volume is valid for their diff covers, but I’m not sure simply adding more ATF to the sumo will lead to much more cooling. But, I bought it anyway, for the drain plug alone. 
 

This is a very helpful forum, and I have been reading all of your and others’ solid advice since March, when I got the truck. Thank you! 

  • Like 1
Grumpy Bear Senior Enthusiast

Grumpy Bear

Posted
Posted
4 hours ago, Gandalf said:

I am a bit concerned about winter.

 

Don't be. Automatics have been radiator cooled since the early 1960's without thermostats. I mentioned in another post this thermostat does not have minimum flow bypass so it isn't even on the cooler until about 140 F. Driving them puts enough heat into it to keep it warm enough for everywhere but the artic circle. 😉 

Gandalf Enthusiast

Gandalf

Posted
Posted

Thanks again! (Hmmm . . . Now to decide what to spend the money on instead. This could become addictive - I’m glad I’ve switched to GM after 30 years innFords!)

 

 

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
 Share
Go to topic listing

  • Latest Articles

  • Posts

    • jgaudet99
      Tire psi

      By jgaudet99 · Posted

      Thanks for all that information, I might purchase one and see if it will work for me, if not they may let me return it! Yes for sure the tires are definitely within limit for my truck empty, and when I do tow I'll definitely make sure to raise the rear psi for the amount of weight that's going to be on it.
    • Chuck FB
      Tire psi

      By Chuck FB · Posted

      Yes exactly, more and more these days people/companies are afraid of liability issues so its easier just to say no rather than risk putting their neck on the line.    I will say with the Autel unit or when I used it last year on my truck, it wasn't like I could choose the 2025 model year or even the 2024 model year as that option was not there to manipulate the placard pressures but had to go back to 2023 or there abouts and then it showed up as an option, odd but that was how the software was then and I can't say one way or the other now as they throw out updates every so often. I still would talk to your tire dealer though to start with and they may do it for nothing but also they may have a comment on a better unit to purchase. All I know is that one of the large tire shops in my area happens to use these Autel units for their use and set them up to use the wifi and all of that jazz for constant updating because each tire tech has one handed to them by the shop but I just plugged it into my laptop to update it and yes if one is bought it has to be registered so you can get the link to do updates and then the unit has to be updated before its even used. I am not at all techy so it took me a bit but anyway just a heads up for anything you buy, most likely it will need to be connected to a computer to access the internet to have it updated to the latest software version before you can put it to use.   If your truck is near empty, those tire pressures you listed are a very safe upper range pressures to carry the weight, both the front and rear as I know they could be run lower yet with an empty truck. And if its a trailer and not some motorcycle your going to strap onto the front of your truck on a rack, you shouldn't have a need to inflate your front tires if your at 55 front already, its the rear ones that would need more air if you have much hitch weight. 
    • jgaudet99
      Tire psi

      By jgaudet99 · Posted

      Thank you, I'll check that Autel scanner out and see if it will work for me! Ya I can see GM's point of view if they lower the psi set value for someone and the person sell's the truck and the new owner puts the factory tires back on then their could be liability issues cause the psi warning light wasn't coming on when the tires were under inflated for towing their load and then it might be able to be traced back to GM lowering it.
    • Chuck FB
      Tire psi

      By Chuck FB · Posted

      I had a similar but different response when I talked to the service manager where I bought my truck in that he said GM corporate won't allow them to lower the placard pressure setting as they would get their hand slapped but that of course they have the ability to make that change. His suggestion was simply go to a tire dealer or third party shop that is willing to reset the pressures lower. However I chose to buy a tpms tool and partly based off of this very forum as it had been proven to work on the 2024 model ( Global B system ) and while I could have paid lots for a full two way diag tool, I didn't want to spend that much and bought the recommended Autel TS 508 and it will reprogram the 2025 model and assume it should do the 2026 as well. However the tool is rather proprietary to reprogramming Autel tpms sensors so that is a function I will never use, where as a real two way scanner would have many uses but also have yearly subscriptions etc where this 508 is free updates for as long as they put updates out for the unit. In any event it worked to lower the placard pressures and I often use it to adjust my actual tire pressures although will check with a mechanical gauge as well sometimes just to make sure that tires tpms sensor isn't lying to me.    My suggestion is either buy a tool that you know will work to adjust the system or start out by getting the tire shop you bought your tires from to reset your truck and if after that you still want a unit to do it yourself, get one at that point. 
    • jgaudet99
      Tire psi

      By jgaudet99 · Posted

      Here is an image of a quick Google search about these tires on my truck and it's exactly same psi recommendation the Toyo tires company gave me!    I'm not looking for anyone else recommended psi or anything, I'm just looking to see if anyone knew a way to get rid of the factory low psi warning light, because I'm not running high psi and ruining my tires when I'm not towing! 

  • GM-Trucks.com Clubs

  • Popular Contributors

×
×
  • Create New...