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Cjmooch

Transmission gets hot under load? Mainly in mountain driving...?

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So I have a little issue with my transmission.

 

Long story short my original transmission went out on my 2014 Silverado at 73,000 miles 4 months out of warranty in April 2019. I got it replaced by chevy because they gave me a decent deal because it was close to the warranty and its a manufacture rebuilt transmission. So basically when transmissions go out like mine, they send them to the factory to get rebuilt by chevy then put into another truck. Everything was fine with it until I drove from Texas to Colorado this summer. When I was driving on the higher elevation highways and going uphill the transmission was getting hot, got to around 215 a lot of the time. Id pull over when I could to let it drop but got as hot as 225. Normal operating temps are 195-200 per the manual. Normal driving its perfectly fine, just under load such as going uphill for miles in the mountains it was getting hot.  

 

So first question for anyone that lives in the higher elevations and mountain regions that often drive on steep grades, is this normal? I really do not imagine so, but I could be wrong.

 

Second, could it be something that when installing the new transmission, something could be missing or not installed right? I know nothing when it comes to transmissions, but with engines you have the thermostat that deals with cooling of the engine. Is there a similar set up with transmissions that this could be faulty?

 

Third, is there any good options out there for upgrading the cooling system for the transmission? If so, let me know because I take road trips all the time in my truck and I dont want to have to worry about the transmission overheating anytime im going uphill

 

I took it to the dealership this weekend, but I highly doubt they will figure it out because it cant be recreated in the flatlands of the great state of Texas, so lets see what yall have to say.

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It is a 6 or a 8speed. Big differences.
But options are bigger pan put that will not be as big of a impact on your use. Then a thermostat delete....
Buy best mod is a truck cool max cooler in the grill. And also a radiator line delete. Lines go to the radiator to warm it up and then condenser to cool it down. Get it out of the radiator and the huge trans cooler in the grill and you will never have that issue. Also a tune will reduce the slip and the wear and heat build up.
But really all you need is a real trans cooler. And it is cheap few hundred. Sure beats stuck on side of road or cost of trans.

Sent from my SM-N960U using Tapatalk

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6 minutes ago, 1SLOW1500 said:

It is a 6 or a 8speed. Big differences.
But options are bigger pan put that will not be as big of a impact on your use. Then a thermostat delete....
Buy best mod is a truck cool max cooler in the grill. And also a radiator line delete. Lines go to the radiator to warm it up and then condenser to cool it down. Get it out of the radiator and the huge trans cooler in the grill and you will never have that issue. Also a tune will reduce the slip and the wear and heat build up.
But really all you need is a real trans cooler. And it is cheap few hundred. Sure beats stuck on side of road or cost of trans.

Sent from my SM-N960U using Tapatalk
 

This is great information and if I made add using a quality full synthetic AFT fluid will also help.  Synthetic resists break down at higher temperatures to help increase transmission life, plus it helps keep it cleaner inside. 

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I’d swap out front and rear Diff fluid with new high end 100% synthetic as this can help as well as draining out your current transmission fluid with same 100% synthetic. Nothing helps more with moving parts than 100% synthetic products designed to help cool and fight against thermal breakdown much much more efficiently.




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215º isn't that bad, the fluid can handle that just fine but 225-230 is getting up there.

 

I notice in your picture that the truck is lifted with larger tires, if that is true that is another reason the temps can creep up there because it's more wind resistance and a larger load put on the transmission to keep it at speed.

 

I'd do the thermostat mod and see where you stand, it always seems to drop the temps a good 15-30 degrees from all of the threads I've read.

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Dexron VI is synthetic and the diffs come with synthetic fluid as well. I wouldn't say it's amsoil quality synthetic, but don't see it making that much of a difference in this situation. Seems to me there's something more going on causing this issue. I pulled a loaded car hauler 3 hours in 95 degree heat at 80 mph and my trans never hit 200 degrees. It's possible the factory coolers are clogged from the previous trans failure.

Sent from my SM-N975U using Tapatalk

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Is there a similar set up with transmissions that this could be faulty?  

 

YES, and that is one main issue. Not faulty, but trans fluid is kept to reach about 200 F before it gets cooled with this thermostat the factory had installed. Transmission thermostat delete will handle the continuous circulation of the fluid to keep it cool. I have done mine and it dropped about 50-55 F. That is the first must, then as what 1SLOW1500 have said is to install a cooler that will drop trans fluid temperature under the heavy load and use.
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On 10/14/2019 at 4:33 PM, 1SLOW1500 said:

It is a 6 or a 8speed. Big differences.

Shows he has a '14, no 8-speed that year (and only an 8-speed in the '15 L86 trucks).  So he is rocking a 6L90E.

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