Chevy Max Trans Temp

[CurtPutnam]

Rather than starting another zombie thread, I'll state that my dealer looked up the answer for my 2018 2500 and the answer is the same as in this sticky:

http://www.forestriverforums.com/for...ture-9989.html

270º short time max. If you get there, change the transmission oil PDQ.

[TitanMike]

Originally Posted by CurtPutnam

Rather than starting another zombie thread, I'll state that my dealer looked up the answer for my 2018 2500 and the answer is the same as in this sticky:

http://www.forestriverforums.com/for...ture-9989.html

270º short time max. If you get there, change the transmission oil PDQ.

Simple fact. The rate oil oxidizes doubles for every 18 degrees above 160 degree's F. This can be altered somewhat by the use of additives but they only cover up this basic "rule". Heat oxidizes the trans fluid (oil) which creates varnish like materials which then build up on the friction materials ina transmission. As they do so they alter the friction characteristics which allow slippage. As slipping increases more heat is generated. vicious cycle continues until transmission fails.

This isn't unique to Chevy transmissions but pretty much all.

Of course one item that helps a lot is an add-on transmission fluid cooler. Some heavy duty rigs will have one with fans mounted outside the engine compartment (sometimes under the chassis) with thermostatic controls on the fan.

If one is seeing heat in the mid to high 200's plan on frequent trans fluid changes. Lot's cheaper than replacing/overhauling transmissions.

[babock]

If you look at some of the charts on the internet, they have a ATF fluid life vs temperature. Many of these are outdated since the fluid has changed since those charts came out.


That being said, I would try to keep fluid temps under 240 if at all possible. On my last truck, I put a large cooler on it and I kept temps below 190. On my new truck, this transmission is designed to never operate below 200 and they actually have a thermostat in the transmission to keep it from going below that. So far, I have never gone over 225 going up steep grades in the Sierra Nevada on hot days.


To me, its a good idea to change the ATF sooner than recommended. I am going to do a fluid change at 30K and every 30K thereafter. My method will be to change the 3 qts in the pan....drive around...and do this multiple times.


On my last Chevy Silverado, I did a different method that didn't do the dilution method I have to do on this truck. I would never take my truck in and do a power flush exchange.

[CurtPutnam]

Originally Posted by babock

If you look at some of the charts on the internet, they have a ATF fluid life vs temperature. Many of these are outdated since the fluid has changed since those charts came out.


That being said, I would try to keep fluid temps under 240 if at all possible. On my last truck, I put a large cooler on it and I kept temps below 190. On my new truck, this transmission is designed to never operate below 200 and they actually have a thermostat in the transmission to keep it from going below that. So far, I have never gone over 225 going up steep grades in the Sierra Nevada on hot days.


To me, its a good idea to change the ATF sooner than recommended. I am going to do a fluid change at 30K and every 30K thereafter. My method will be to change the 3 qts in the pan....drive around...and do this multiple times.


On my last Chevy Silverado, I did a different method that didn't do the dilution method I have to do on this truck. I would never take my truck in and do a power flush exchange.

Service tech recommended staying at < 240º as you said.

Why do you not recommend a power flush? I'm quite ignorant on the subject.

[TitanMike]

Originally Posted by babock

To me, its a good idea to change the ATF sooner than recommended. I am going to do a fluid change at 30K and every 30K thereafter. My method will be to change the 3 qts in the pan....drive around...and do this multiple times.

Lots of people do it this way but all you get in the end is diluted old ATF. Never a fill of fresh.

I prefer to use the Dealer for this service. Costs me ~$150 and they use a machine that returns one fresh quart of ATF for every quart of old removed. This flushes out the Converter as well. I do it every 50k. This includes the cost of the ATF and in the end I don't have to dispose of the old, clean up my garage floor, or crawl around under my truck.

[DieselDrax]

Related to this, I don't know what other trucks have something similar but my truck's OEM trans cooler is part of the radiator. That's not uncommon. What we found out is that these Colorado/Canyon trucks with the diesel have 2 plastic panels snapped in place that cover nearly the lower 1/3 or so of the radiator. Why? No idea. They pop out very easily, though, and trans temps when towing are 15-20F cooler with them removed. Highest trans temp I saw towing before was 235F in Colorado with it running around 215-225F the rest of the time.


After removal the highest temps I see are 225F with it running around 200F most of the time while towing. Nothing like a free mod to lower trans temps.


For modern GM transmissions that use Dexron-VI ATF, GM has said both the fluid and transmissions are able to withstand up to ~270F temps without issue. Yes, hotter temps cause the ATF to oxidize and require more frequent changes but it doesn't happen instantly. If you saw a temp of 270F and the trans temp warning was triggered that doesn't mean your trans fluid suddenly has no more life. It's temp over time. Frequent towing, I'd recommend changing the ATF around 30k miles.


For reference, here's fresh fluid vs my fluid w/ just under 30k miles on it and about 6,000 miles towing prior to removing the panels mentioned above so it was running hotter than it does now. Doesn't look or smell awful, but I'll definitely be changing it in the near future.

[babock]

Originally Posted by TitanMike

Lots of people do it this way but all you get in the end is diluted old ATF. Never a fill of fresh.

I prefer to use the Dealer for this service. Costs me ~$150 and they use a machine that returns one fresh quart of ATF for every quart of old removed. This flushes out the Converter as well. I do it every 50k. This includes the cost of the ATF and in the end I don't have to dispose of the old, clean up my garage floor, or crawl around under my truck.

I used to do complete changes on my Chevy. I would drop the pan, replace the fluid and then run the truck with the return line into a pan for 2 qts. I would then add 2 qts and repeat the process. I would continue these steps until new fluid started coming out. On my new truck, you can't do it this way because of the thermostat. The dealers don't even use the machine you mentioned because of it. Since that is not an option, I have to do the dilution method.


Since the capacity of the transmission in my truck is 13 qts and I can only change 3 qts at a time, that is why I will be doing the 30K interval.


Every time you do a change you are changing 23% of the fluid. Do 15 qts worth and you will be at a 73% change. That's not bad.

[TitanMike]

Originally Posted by babock

I used to do complete changes on my Chevy. I would drop the pan, replace the fluid and then run the truck with the return line into a pan for 2 qts. I would then add 2 qts and repeat the process. I would continue these steps until new fluid started coming out. On my new truck, you can't do it this way because of the thermostat. The dealers don't even use the machine you mentioned because of it. Since that is not an option, I have to do the dilution method.


Since the capacity of the transmission in my truck is 13 qts and I can only change 3 qts at a time, that is why I will be doing the 30K interval.


Every time you do a change you are changing 23% of the fluid. Do 15 qts worth and you will be at a 73% change. That's not bad.

Regardless of method, at least you're doing SOMETHING. Usually people just wait until they have tranny problems and then get it repaired or replaced.

[Crusadernoob]

We got an old prehistoric truck, 215k on it. Im just going to throw this out there, trans fluid on ours has never been hotter than 100f over ambient temperature. Just got back from towing through the mountains on 40 TN/NC border and ambient temp was 90+ our transmission temp was 185f the whole trip. I do a drain and fill every year, thats 7.5 fresh quarts.

[babock]

Originally Posted by TitanMike

Regardless of method, at least you're doing SOMETHING. Usually people just wait until they have tranny problems and then get it repaired or replaced.

The manual says do it after 100K. Not waiting that long.

[TitanMike]

Originally Posted by Crusadernoob

We got an old prehistoric truck, 215k on it. Im just going to throw this out there, trans fluid on ours has never been hotter than 100f over ambient temperature. Just got back from towing through the mountains on 40 TN/NC border and ambient temp was 90+ our transmission temp was 185f the whole trip. I do a drain and fill every year, thats 7.5 fresh quarts.

You mentioned a key point. Ambient Temperature. Trans temp will never be cooled below ambient, no matter how many coolers are added.

With that in mind it would be good for people to know what the normal temperature of their transmission is when towing on 70 degree days and then see how it compares when they are towing through Death Valley or Phoenix on a summer day. Super high temps may not indicate a failing transmission in those conditions.

Myself, I'd probably pass through those areas after midnight if possible. Hate heat myself and I'd rather not subject my Tow Vehicle to temps that can cook my dinner.

[Electra glide]

My truck has 150k on it. I bought it 3.5 years ago with 130k on it. No clue if the fluid was ever changed. Reading this thread tells me I should I go get it changed right away.

[babock]

Originally Posted by Electra glide

My truck has 150k on it. I bought it 3.5 years ago with 130k on it. No clue if the fluid was ever changed. Reading this thread tells me I should I go get it changed right away.

I would. And don't listen to the people that say once you go over a certain mileage that its bad to change it. Never a bad time to change it.


Your truck has the Allison tranny with the spin on filter. Easiest transmission to change a filter on. At least do a drain and fill yearly along with changing the filter. Has the filter at least been changed regularly?


Make sure you use the correct fluid for your transmission. Check your manual or go to the Allison site and enter your transmission serial number.




I wouldn't go the power flush route but I would use the method that transfers in fluid as its being extracted like TitanMike used or the way I used to do it.

[elchilero53]

We tow about 5000 miles per year and change the fluid about every 30k - 35k miles whether it needs it or not. The newer Chevrolet Pickup models (2017+) require you drain the tyranny and torque converter then refill; you cannot flush them like you could with the older models.

Our tyranny typically runs about 170-175 degrees on hot summer days. Towing, it runs about 190-195 degrees in the heat. The hottest I've seen it was about 207 degrees after pulling a long 8% grade in the New Mexico/Colorado mountains and boy, were the fans roaring when we hit the top of the grade! It has a nice-sized external tyranny cooler.

[TitanMike]

Originally Posted by elchilero53

We tow about 5000 miles per year and change the fluid about every 30k - 35k miles whether it needs it or not. The newer Chevrolet Pickup models (2017+) require you drain the tyranny and torque converter then refill; you cannot flush them like you could with the older models.

Our tyranny typically runs about 170-175 degrees on hot summer days. Towing, it runs about 190-195 degrees in the heat. The hottest I've seen it was about 207 degrees after pulling a long 8% grade in the New Mexico/Colorado mountains and boy, were the fans roaring when we hit the top of the grade! It has a nice-sized external tyranny cooler.

And that's a good thing. The reason the "Flush/Exchange" machines came to the market place is because manufacturers removed the converter drain plugs. If they've made a return, that's great.

[babock]

Originally Posted by elchilero53

It has a nice-sized external tyranny cooler.

That is key, My 99 chevy had just the trans cooler in the radiator. Starting the next model year they added a very small external one which most people found pretty useless too. After finally putting in a temp gauge and seeing what my temps were going up to, I installed a very large external cooler.

[BigH]

Originally Posted by DieselDrax

Related to this, I don't know what other trucks have something similar but my truck's OEM trans cooler is part of the radiator. That's not uncommon. ....

Most half tons (and under) trucks (government regulated for mileage) use a primary trans cooler that is either inside the radiator for the motor or plumbed to it. This is done to keep the temperature in the transmission up for increased mileage and to provide some control for heat.

HD gas trucks from GM for model year 2017,2018,2019 use two radiators for the transmission. One is a stand alone and one is inside the radiator. The stand alone is in use all the time...the one inside the motor's radiator is only used if you managed to get the trans temp to 195.

-I have no idea how you would get the trans to that temp in my truck. Through eastern Kentucky and Tenn (up and down up and down) my trans got to just over 180 with a 9,500lb trailer. The outside temp was in the 90's and I kept speeds at 70. At a steady 70-75 with the same trailer on flat ground the temp is about 145 -155 depending on the headwind.

[DieselDrax]

Originally Posted by BigH

Most half tons (and under) trucks (government regulated for mileage) use a primary trans cooler that is either inside the radiator for the motor or plumbed to it. This is done to keep the temperature in the transmission up for increased mileage and to provide some control for heat.

HD gas trucks from GM for model year 2017,2018,2019 use two radiators for the transmission. One is a stand alone and one is inside the radiator. The stand alone is in use all the time...the one inside the motor's radiator is only used if you managed to get the trans temp to 195.

-I have no idea how you would get the trans to that temp in my truck. Through eastern Kentucky and Tenn (up and down up and down) my trans got to just over 180 with a 9,500lb trailer. The outside temp was in the 90's and I kept speeds at 70. At a steady 70-75 with the same trailer on flat ground the temp is about 145 -155 depending on the headwind.

Perhaps my post wasn't clear. I wasn't wondering how many other trucks have trans coolers in the radiator, why, or how they work as I said that's not uncommon. Keep reading my post, you'll see what I'm ultimately talking about are panels that block part of the radiator that I ended up removing. I haven't checked so I don't know how common such panels are on other trucks. Not active aero shutters, these are simple, snap-in plastic panels behind the openings in the bumper.


See attached pic. Best view/explanation I can find and no, you don't have to disassemble the front end to get them off. They take 5 mins to get out.

[BigH]

Originally Posted by DieselDrax

Perhaps my post wasn't clear. I wasn't wondering how many other trucks have trans coolers in the radiator, why, or how they work as I said that's not uncommon. Keep reading my post, you'll see what I'm ultimately talking about are panels that block part of the radiator that I ended up removing. I haven't checked so I don't know how common such panels are on other trucks. Not active aero shutters, these are simple, snap-in plastic panels behind the openings in the bumper.


See attached pic. Best view/explanation I can find and no, you don't have to disassemble the front end to get them off. They take 5 mins to get out.

I was just adding to the conversation on Chevy transmissions temps...you touched on something that related to many vehicles...I thought some folks may want to know how and why.

[DieselDrax]

Originally Posted by BigH

I was just adding to the conversation on Chevy transmissions temps...you touched on something that related to many vehicles...I thought some folks may want to know how and why.

Gotcha, no worries.