2014 V6- no transmission cooler available!

ghgmi · July 28, 2015

Transmissions and engines run hotter these days in the name of efficiency. Fluids have improved greatly over the past 10-20 years. The new fluids are designed for these higher temperatures.

I understand that engine are more efficient when hot. I don't understand why that's true of transmissions. Can anyone explain? Mind you, I'm not doubting it, otherwise they wouldn't put thermostats in transmission cooler lines.

Chris · July 28, 2015

I understand that engine are more efficient when hot. I don't understand why that's true of transmissions. Can anyone explain? Mind you, I'm not doubting it, otherwise they wouldn't put thermostats in transmission cooler lines.

Warmer fluid thins. Thinner fluid moves easier and more efficiently. The newer fluid also has higer heat tolerances than the old stuff, Dexron 3 and prior.

ghgmi · July 28, 2015

Warmer fluid thins. Thinner fluid moves easier and more efficiently. The newer fluid also has higer heat tolerances than the old stuff, Dexron 3 and prior.

OK, sure, but I would have thought that to be a small effect. Engines are more efficient hot because combustion is more complete when it's hot. You're probably right, though. I can't think of anything else.

Chris · July 28, 2015

OK, sure, but I would have thought that to be a small effect. Engines are more efficient hot because combustion is more complete when it's hot. You're probably right, though. I can't think of anything else.

I am talking about the trans fluid. One of the basic hydraulic principles

ghgmi · July 29, 2015

I am talking about the trans fluid. One of the basic hydraulic principles

I knew what you were talking about. I was just repeating the idea that I "get" the point w.r.t. engines more.

I understand that pushing a thinner fluid around the trans is easier than pushing a thicker fluid, but the trans is pushing around a 5000 lb truck so I would have though the advantage of thinner fluid to be small in the grand scheme of things.

Chris · July 29, 2015

I knew what you were talking about. I was just repeating the idea that I "get" the point w.r.t. engines more.

I understand that pushing a thinner fluid around the trans is easier than pushing a thicker fluid, but the trans is pushing around a 5000 lb truck so I would have though the advantage of thinner fluid to be small in the grand scheme of things.

With CAFE laws, 1 MPG on an entire pickup line makes a big difference. It allows them to not get fined by the government. Dont read into it that much. Flashpoint is 356° F. It has a thermostat to send to a cooler built in.

Spurshot · July 29, 2015

Here's an old 2009 thread where Ryan asked the question about ATF temps.

http://www.gm-trucks.com/forums/topic/102552-trans-temp-while-towing/

I quoted this out of my 99 1/2 GMC2500 manual at the time, but I would check the K2 manual.

From my 99 2500 Sierra owner's manual (Dexron III).

If you vehicle has a heavy duty automatic transmission, you will have a transmission temperature gage.

When your ignition is on, the gage shows the temperature of the transmission fluid. The normal operating range is from 100*F (38*C) to about 265*F (130*C).

At approximately 265*F (130*C), the message center will display a TRANS FLUID HOT message and the transmission will enter a transmission protection mode. When the transmission enters the protection mode, you may notice a change in the transmission shifting patterns. The transmission will return to normal shifting patterns when the transmission fluid temperature falls below 260*F (127*C).

See "Message Center" in the Index for further infomation.

If the transmission fluid reaches temperatures of approximately 275*F (135*C) or greater, the message center will display a TRANS HOT...IDLE ENG warning message. Pull the vehicle off the roadway when it is safe to do so. Set the parking brake, place the transmission in PARK (P) and allow the engine to idle until the transmission fluid temperature falls below 260*F (127*C). If the transmission continues to operate above 265*F (130*C), please contact your nearest dealer or the GM Roadside Assistance Center.

Spurshot · July 29, 2015

Section 11-5 of our owners manual says 97,500 miles for "normal" use change interval and section 11-7 shows a 45,000 mile interval for "severe" use. I couldn't find a reference to temperature limits.

Brian S. · July 30, 2015

I started this thread a year ago, and what I did about this situation is buy a 2015 Sierra with the 5.3l in February. (has the external cooler)

The new fluids may not break down as easily as the old ones, but I'm old school. You don't get past 30 years of hearing "Heat is the enemy of your transmission and if your tow anything you should have an external cooler" because the fluid is better.

The 5.3 and the 6.2 have it standard equipment, and transmission coolers aren't exactly an expensive part. No way I'd tow 5000lbs with a truck with no cooler.

arkenzo · July 31, 2015

I started this thread a year ago, and what I did about this situation is buy a 2015 Sierra with the 5.3l in February. (has the external cooler)

Your solution to achieving cooler transmission temperatures was to buy a new, more expensive truck? Seems logical to me!

Brian S. · July 31, 2015

Is there a "bad" reason to buy a new GM truck? I can't think of one!

The dealer I bought the 2014 from said GM had no part, they would not install an aftermarket part, and that it may void my warranty to have an aftermarket part installed.

The new 4.3l is a VERY good engine, if GM puts an external cooler on the transmission in upcoming years I would not hesitate to consider one again.

SouthernSilveradoGuy85 · July 31, 2015

Heat when it comes to vehicles is almost like one of those things that it needs to be in the middle for optimal performance. Almost like wanting it to be in that sweet spot. You need the temps at normal operating temps while not getting too hot. But, not hot enough can also to damage.

I haven't towed a trailer yet and I don't regularly monitor my trans temp, but I haven't seen over 200°F yet, even on 100° days. A good rule of thumb is that the trans at operating temp should be about 100°F more than the ambient temp. So if it's 85°F outside then the trans temp shouldn't be no more than maybe 190°F. Mine usually stays around 195° at the most, at least from the times I've checked it out of curiosity.

Brian S. · July 31, 2015

I had a "worst case scenario" trip where I was towing my boat on a curvy, hilly back road and the transmission temp hit 230-240 degrees.

My wife was with me and she said, "What do you care? You've never owned a truck outside the warranty period, if it breaks, they'll fix it".

I care because one of the reasons I buy a new truck every three years is I don't want to be stranded on the side of the road (especially towing my boat) and I don't want to be inconvenienced by having my car in the shop.

Spurshot · July 31, 2015

I had a "worst case scenario" trip where I was towing my boat on a curvy, hilly back road and the transmission temp hit 230-240 degrees.

My wife was with me and she said, "What do you care? You've never owned a truck outside the warranty period, if it breaks, they'll fix it".

I care because one of the reasons I buy a new truck every three years is I don't want to be stranded on the side of the road (especially towing my boat) and I don't want to be inconvenienced by having my car in the shop.

I like your wife's attitude. That's a "best case" wife. Keep her. Besides, if it trashed the trans, you'd have a green light for a new 6.2L 2016. But realistically, 240 isn't even breaking a sweat with Dex VI.