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Transmission Thermostat Delete Pros vs. Cons


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dont throw your old trans oil away, that stuff is great to fill up a pressurized weed sprayer and spray down loose gravel and dirt roads.  its also good for rust inhibitor on chassis and leaf spring lube

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i did the flip on the weekend, i have 120k miles on my transmission. it was 82 f outside and i drove 80 mph for 30 miles and the temp stayed at 156. before it was always above 200. when it was above 2

Little 5 quarts ATF rejuvenation followed with the new ATF thermostat being installed. Curious to see if driveability will change at all and interested to see how ATF temps are altered.

Absolutely correct. The cooler indeed has a thermal limit and if the load (towing) is higher than that limit it will still get hot. An additional cooler is warranted. If road speed (stalled in traffic

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The fluid may never make it to the radiator. Leaving the transmission, when it gets to the thermostat housing it will take the path of least resistance and get sucked back into the transmission. Flipping the pill, blocks the short cut and forces the fluid to the radiator and then back to the transmission.

2 hours ago, SeekAndDestroy said:

Can you just take the spring and thermostat (pill) out of the housing? Why do you flip it and not remove it? 

 

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28 minutes ago, Eddie 70 said:

The fluid may never make it to the radiator. Leaving the transmission, when it gets to the thermostat housing it will take the path of least resistance and get sucked back into the transmission. Flipping the pill, blocks the short cut and forces the fluid to the radiator and then back to the transmission.

 

Ok. That’s why he taps and plugs the hole. Makes sense now. Thank you!

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4 hours ago, SeekAndDestroy said:

Ok. That’s why he taps and plugs the hole. Makes sense now. Thank you!

I love it when honest people ask honest questions with the intention of learning something new. Thank you. 

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We took my truck to Knoxville tonight. Ran around a little. We stopped by Chick-Fil-A and sat in line for a few minutes. The trans temp got up to 158*F while in line. That was the highest I saw during the whole trip. We live about 5 miles away from Chick, the temp dropped back down to 153*F before we got home. So it is cooling and maintaining pretty cool. I am pretty happy with that outcome so far. I'll still do my 15k mile one gallon transmission fluid change. It's cheap enough and easy enough and may help. It cannot hurt.

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23 hours ago, Eddie 70 said:

We took my truck to Knoxville tonight. Ran around a little. We stopped by Chick-Fil-A and sat in line for a few minutes. The trans temp got up to 158*F while in line. That was the highest I saw during the whole trip. We live about 5 miles away from Chick, the temp dropped back down to 153*F before we got home. So it is cooling and maintaining pretty cool. I am pretty happy with that outcome so far. I'll still do my 15k mile one gallon transmission fluid change. It's cheap enough and easy enough and may help. It cannot hurt.

Eddie 70.....I just did the "flip" today. Took the truck out for a 30 min. spin & temp got up to 145F.  I saw it get up to 147F once buy drop back down to 145 within seconds. This is about 40 degs. cooler than the 185 that it would normally run. I too will be doing a drain (vacuum actually)  & fill of 5qts through the dip stick hole every 15-20k miles. (as well as other fluids)

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7 minutes ago, rav3 said:

Eddie 70.....I just did the "flip" today. Took the truck out for a 30 min. spin & temp got up to 145F.  I saw it get up to 147F once buy drop back down to 145 within seconds. This is about 40 degs. cooler than the 185 that it would normally run. I too will be doing a drain (vacuum actually)  & fill of 5qts through the dip stick hole every 15-20k miles. (as well as other fluids)

Sounds like we are on a similar path. I pull a gallon (vacuum) out the dipstick. 5b11d8e4cc676_TransmissionFluid1.thumb.jpg.8117b15c2ecf52420957d3378d09a963.jpg

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23 minutes ago, Eddie 70 said:

Sounds like we are on a similar path. I pull a gallon (vacuum) out the dipstick. 

Yes it does. However, I use a home made vacuum pump that runs off my compressor. With warmed up fluid, I can suck about 5 qts out of my '17 6 speed. I buy (2) gallon jugs of AC Delco's fully synthetic Dexron VI ATF at Amazon, do the transmission & transfer case. (Also us it to remove the old brake fluid from the brake reservoir and I also remove the rear differential fluid that way) 

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51 minutes ago, Eddie 70 said:

So this is after my 43 mile ride to work this morning.

 

Trans Temp Work.jpg

Now the question becomes........is this too cool for our 6 speed transmissions?

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8 minutes ago, rav3 said:

Now the question becomes........is this too cool for our 6 speed transmissions?

Tell ya what. Put it back the way it was and this winter on this trip tell me what you get. Actually, don't tell me. Just think about it. 

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I drove my truck about 500 miles, round trip, yesterday on the interstate. Got stuck in wreck traffic. The temp got up to 168*F. When we got moving the temp dropped back down to around 158*. Never did the temperature get above 168* the entire time. I saw 96* on the outside temperature. My truck managed to show 23.1MPG on the DIC.

 

Take from that information, what you want, but I would say for myself, I am satisfied.

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10 minutes ago, truckguy82 said:

I’m more curious about the winter temps, i would have zero concern if it was summer all the time

@truckguy.....This is a good question. With that said, I think it depends on how far you drive. Even before or after my thermostat delete, If I did a 15-20 min. drive, the temperature never got to a point that the thermostat would open up, so that drive wouldn't make a lot of difference on transmission temperature. I think yesterday morning when it was 68F outside it got up to maybe 120F.  So, exactly how far do you need to drive to get the transmission fluid up to the "open thermostat" temperature?

If it's winter, the same case would apply. How far would you need to drive when it's 32 deg. F outside for either version to get up to say 130 F? It's my understanding that the temperature rise only comes from the friction created inside the transmission & not from, say, the temperature on the engine or radiator. Correct me if that's not the case.

So bottom line, what's the best temperature for the fluid? or the transmission?  140/150F? or 180/200F? And remember, as it's been pointed out earlier, pre 2014 trucks didn't have this thermostat, so theirs would be the same as the ones that did the delete mod.

FYI, yesterday evening, we drove up the Blue Ridge Parkway from 2100' elevation up to Mt Pisgah (5000')  and the trans temperature was around  140F ish. Dropping down to 2200' elevation the temperature may have dropped to 135F. However, when I hit stop & go traffic while returning home, the temperature when up to 160F. I've never seen it that high so far since I flipped the pill.

As the cooler temperatures arrive this fall & winter, I'll be keeping an eye on the trans. fluid temp to see how it reacts.

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