K2XX Trans Cooler Thermostat Thoughts and Opinions

[Spurshot]

Question for those that have studied this a lot more than I:  Is an open/no thermostat/pill flip going to give a quicker transmission fluid warm-up than a thermostat equipped transmission?  I ask this because I believe my K2 routes the fluid through the engine coolant radiator, which warms very quickly.  My question is more in the context of cold weather below freezing.

Edited August 17, 2022 by Spurshot

[rav3]

1 minute ago, Spurshot said:

Question for those that have studied this a lot more than I:  Is an open/no thermostat/pill flip going to give a quicker transmission fluid warm-up than a thermostat equipped transmission?  I ask this because I believe my K2 routes the fluid through the engine coolant radiator, which warms very quickly. 

It's my understanding that when the transmission thermostat is closed no fluid flows to the radiator. However, when "pill flip" is done, transmission fluid flows to radiator cooler all the time.

Please let me know it this is correct.

[Grumpy Bear]

41 minutes ago, rav3 said:

It's my understanding that when the transmission thermostat is closed no fluid flows to the radiator. However, when "pill flip" is done, transmission fluid flows to radiator cooler all the time.

Please let me know it this is correct.

 

Yes this is correct. 

 

 

[Grumpy Bear]

49 minutes ago, Spurshot said:

Question for those that have studied this a lot more than I:  Is an open/no thermostat/pill flip going to give a quicker transmission fluid warm-up than a thermostat equipped transmission?  I ask this because I believe my K2 routes the fluid through the engine coolant radiator, which warms very quickly.  My question is more in the context of cold weather below freezing.

 

This is a tough one because it is not intuitive. These lines are the stable temperature of the fluid ONCE up to temperature. An hour or more of interstate driving at the noted speed. Yellow is the new thermostat and the other two 'pill flips' with different water thermostats. 

 

Lets look at the first orange dot at 10 F and first yellow at the same temperature. Obviously the temperature is higher with the thermostat. However what the graph does not show is how rapidly either got to 110 F ATF temperature and that is the question you are asking. Hardly a difference in any conditions I could tell as long as you are moving. If however you are a 'have a cup while she warms up for 20 minutes' then the pill flip heats quicker but to the lower value. Most of the heat comes from working the fluid which only happens to any great degree while under load. 

 

Hope that was helpful. 

 

[customboss]

28 minutes ago, Grumpy Bear said:

 

This is a tough one because it is not intuitive. These lines are the stable temperature of the fluid ONCE up to temperature. An hour or more of interstate driving at the noted speed. Yellow is the new thermostat and the other two 'pill flips' with different water thermostats. 

 

Lets look at the first orange dot at 10 F and first yellow at the same temperature. Obviously the temperature is higher with the thermostat. However what the graph does not show is how rapidly either got to 110 F ATF temperature and that is the question you are asking. Hardly a difference in any conditions I could tell as long as you are moving. If however you are a 'have a cup while she warms up for 20 minutes' then the pill flip heats quicker but to the lower value. Most of the heat comes from working the fluid which only happens to any great degree while under load. 

 

Hope that was helpful. 

 

Great point, if one can reduce the fully heated temp of the engine oil and coolant (your two of three  heat exchange mediums, air flow through heat exchangers the primary)  you might lower max stabilized temp.  Ask me how I know....LOL  

 

 

[pokismoki]

1 hour ago, Spurshot said:

Question for those that have studied this a lot more than I:  Is an open/no thermostat/pill flip going to give a quicker transmission fluid warm-up than a thermostat equipped transmission?  I ask this because I believe my K2 routes the fluid through the engine coolant radiator, which warms very quickly.  My question is more in the context of cold weather below freezing.

if your in cold climate and have done the thermostat delete, and you feel the trans could use some heat to improve shifting...

you can simply and firmly, step on the brake pedal and hold down the throttle pedal.. sounds crazy, but Torque Management will take over and disable the clutches and you wont have any driveline connection. this should improve wam-up in winter and get heat into the fluid while the computer holds the rpms at a certain safe level

[pokismoki]

46 minutes ago, Grumpy Bear said:

 

This is a tough one because it is not intuitive. These lines are the stable temperature of the fluid ONCE up to temperature. An hour or more of interstate driving at the noted speed. Yellow is the new thermostat and the other two 'pill flips' with different water thermostats. 

 

Lets look at the first orange dot at 10 F and first yellow at the same temperature. Obviously the temperature is higher with the thermostat. However what the graph does not show is how rapidly either got to 110 F ATF temperature and that is the question you are asking. Hardly a difference in any conditions I could tell as long as you are moving. If however you are a 'have a cup while she warms up for 20 minutes' then the pill flip heats quicker but to the lower value. Most of the heat comes from working the fluid which only happens to any great degree while under load. 

 

Hope that was helpful. 

 

i would enjoy seeing one of your graphs after a trans cooler install, any plans for one?

[Grumpy Bear]

2 minutes ago, pokismoki said:

i would enjoy seeing one of your graphs after a trans cooler install, any plans for one?

 

 When I put the Dizzy project to rest one way or the other...Yes. 

[Salsa De Piña]

2 hours ago, pokismoki said:

if your in cold climate and have done the thermostat delete, and you feel the trans could use some heat to improve shifting...

you can simply and firmly, step on the brake pedal and hold down the throttle pedal.. sounds crazy, but Torque Management will take over and disable the clutches and you wont have any driveline connection. this should improve wam-up in winter and get heat into the fluid while the computer holds the rpms at a certain safe level

Or, you know, just drive it.

[rav3]

13 minutes ago, Salsa De Piña said:

Or, you know, just drive it.

Just know, with the pill flip or added thermostat delete, your transmission will work just like all the other PRE K2XX transmissions. The transmission thermostat was an emissions & EPA thing, just like the added auto "start/stop" on newer vehicles. Trying to save a teaspoon of gas but let you pay for the transmission repairs, new starter, battery and whatever else is needed to get that extra .001% MPG or reduced emissions or meet the new MPG requirements. Sorry guys....Just had to rant a little

 

 

[Spurshot]

8 hours ago, Grumpy Bear said:

... However what the graph does not show is how rapidly either got to 110 F ATF temperature and that is the question you are asking. Hardly a difference in any conditions I could tell as long as you are moving. If however you are a 'have a cup while she warms up for 20 minutes' then the pill flip heats quicker but to the lower value. ....

 

Hope that was helpful. 

 

 

GB, Thanks. That lines up with what I was thinking as well.

[steelerdude15]

I went ahead and bought the new thermostat today. I’m going to swap it in when I do my next oil change in a couple hundred miles.

[SeekAndDestroy]

Bought the new valve, 86774933. Tried to install on my 8L90 but the housing itself is about 3/4" shorter than the stock one. The lines were too short to reach so they were not lining up square to the hole. I could have used a tubing bender to massage them into the proper orientation, but that would have been a lot of work under the truck. I swapped the internal parts over to the stock housing.

 

The machining on the new housing was not very good. Lots of burrs, nicks and scratches. Also where they cut the "tubes" that go into the trans there was a .015" mismatch where they over cut into the body. I'm a machinist and this really irked me, lol.

 

Went for an hour drive and the hottest it got was 68C (154F). Outside temp was 15C (59F). I was driving it hard on some backroads outside of town at highway speeds, then about 20 minutes home in stop and go traffic. Temp would stay at 68 then drop to 65, climb to 68 and so on. I'm happy with the new temp. This should be better than the pill flip in winter because it gets cold here. 
 

Edited April 23, 2023 by SeekAndDestroy

[Rusty Shackleford]

I guess I'll jump in on this one if y'all don't mind.

 

A little background, '18 Silverad 5.3/6L80E 2wd. Bone stock. Bought the truck new with the express plan of leasing it to my company on a mileage basis. I drive a lot for work, average 50k miles a year. The truck drives at about 40-50% payload all the time (tools and what-not).  Some personal use towing the boat and stuff, never even approaching what it should be capable of. Mostly highway miles though, commuting daily 50miles one way to and from the office, or on road trips. To date the truck has seen about 32 states, and lives in Texas (for weather reference).

 

1st converter failed at 97k, took the trans with it (as it will do), while under a crappy 100k extended warranty. EW company wanted to put an LKQ (used) transmission in it, I ended up paying $1k out of pocket to get a crate trans installed because it came w/100k warranty. No TSB at this time, dealer put the 190f stat back in it and I didn't know any better at the time.

 

Factory service at 48k on the 2nd trans showed almost clear fluid, but definitely smelled toasty. TSB might or might not have been out around this time, I will give them the benefit of the doubt by saying it wasn't.

 

187k, 2nd converter goes and takes the trans with it (as it will do), and dealer replaces it, charging me like $125 for incidentals, and installs the 145f stat. So far I'm making out like a bandit, 3rd crate unit in for less than $1,200. But in 13k miles she's all mine, no warranty on the latest transmission.

 

Now, I never paid much attention to trans temps until the latest one got installed. But my dash now lives on this screen. Last summer I saw road temps over 100f more days than I can remember, often exceeding 115f. Open road driving with the 145f stat I could hold in the 170's if I kept it under 70mph, 75-80mph pushed trans temps into the 180's, and 85mph made it run high 180's to mid 190's. In town, stop and go summer traffic, 180's were the norm. Yes, we have roads in Tx up to 85mph speed limits.

 

I decided to leave everything alone thru winter, but recently did the Superior kit STL010, about 2weeks ago. While we have yet to see summer conditions, I am seeing that the stat delete will not make a bit of difference once the oven is on. But it does take significantly longer to get up to temp from a cold start. I've seen temps down to the low 40's since the delete, while it takes a bit to warm up I don't have any shifting issues, and once up into the 130's it tends to remain there or higher.

 

My next move, possibly this weekend, is to put and derale fan/cooler under the bed tapped in the return line from the front cooler, and switch it at 160 on/145 off. In a few weeks it is getting a billet converter, new pan w/drain plug, and amsoil fluid, etc. I'm researching what's involved with the r&r now, will do it all myself. Will also get some programming done at that point, talked to tuner that says he can also make some improvements that should help, as well as change a few other little things I want done while in there.

 

I'm at 230k miles on the truck now with no other major issues. I've deleted the unnecessary blades from the grill shutters to eliminate a spiking engine temp issue on the freeway, done plugs/wires, replaced the water pump/eng stat, uca's & lbj's, been thru a couple of batteries, several sets of AT tires, nothing that shouldn't be expected for the mileage. The oil drain plug starts quivering if I just bend down next to the truck. Valvoline high mileage 0-w20 comes out only slightly darker after 6k miles, and it drinks about a half quart between changes as it always has.

 

I do love my truck, and take good care of it. I just wish Chevy hadn't used us owners as the R&D dept for their transmissions.

 

Anyway, sorry for the novel, will chime back in when I get the cooler installed. My goal is to keep the trans as cool as I possibly can (within reason) and if I start having shifting problems then I'll take a step back.

 

 

 

Edited April 28, 2023 by Rusty Shackleford

[Piggy]

Has anybody installed the Mishimoto transmission oil cooler?  
 

I installed the new 70* thermostat.  Not towing and at highway speeds tranny temp maintains around 160*F.  Stop and go traffic temperature creeps up to 175*F.  Towing 5000 Ibs driving in mountains at 82*F outside air temperature, transmission temperature rises  to as high as 212*F.  Towing 5000Ibs on level highway, 62 mph, outside air temperature 82*F, tranny temp stays at around 175*F.  The truck is a 2015 5.3 SLT Terrain with 6L80 with only 38,000 miles, with towing package installed.

Tranny fluid and filter was changed at 25,000 miles with fluid exchange machine at dealer and fluid is clean.

Apparently the torque converter expands and rubs on its housing, eventually destroying the tranny.  I’m thinking by installing the Mishimoto tranny cooler, one is guaranteed that the tranny temperature is always around 160*F and hopefully with changing the tranny fluid often will result in a longer lifespan of the tranny.  Obviously the truck is not designed to keep the tranny  fluid at 70*C, even with the new thermostat, when towing or city driving.  I live in Canada where winters get very cold as well.  According to Mishimoto, the tranny temp drops by 37%:

 

https://www.mishimoto.com/engineering/2019/01/chevrolet-silverado-2014-transmission-cooler-rd-pt3?utm_source=silveradosierraforum&utm_term=continue#continue

 

I just installed a mishimoto radiator in my 1986 Mustang GT and their products appear to be good quality . (Although not cheap)