6l80 getting hot when at idle

[Arturoej8]

Hello I have a 2018 Silverado (6l80) I’ve recently had my transmission rebuilt along with a billet converter installed about 6 months ago. Truck runs fine but I’ve noticed my temperature get up to 200-220 when at idle. Once I hit the road it drops down between 170-190, when running on the highway I’m at 150-170. I’m also running a sure cool for the thermostat. Any idea why it would get up to those temps during idle ? 

[Grumpy Bear]

Yep, no air flow through the cooler. 207 F water thermostat and around a 215 F fan kick in.

No air, no cooling. 

[Arturoej8]

53 minutes ago, Grumpy Bear said:

Yep, no air flow through the cooler. 207 F water thermostat and around a 215 F fan kick in.

No air, no cooling. 

So that would also cause the transmission to heat up? Would you recommend anything ?

[Grumpy Bear]

1 hour ago, Arturoej8 said:

So that would also cause the transmission to heat up? Would you recommend anything ?

 

Do you have a need to idle that long? If it's running, drive it. 

 

If you must idle forever and a day I'd fit it with a Derale cooler (or similar), that has a thermostatic fan. 

 

Derale Performance | The leader in performance cooling!

[swathdiver]

If you are driving on the highway or in city traffic and begin idling it is normal for the temps to jump up for a bit and then the temp will come down.  

 

What temperature is your Sure Cool set for?  Is the billet converter smaller than 300mm and a higher stall than stock?

[rlcole321]

Better check and make sure you don't have a restriction in the trans cooler system, did the previous trans/converter failure dump metal into the system? did you flush thoroughly?

[Grumpy Bear]

Bottom line. Your truck is fine. Modify a bad habit stop idling for a half hour plus without a darn good reason and realize that when shutting down is not possible, like stuck in crawling accident traffic, this is what happens. Change fluid more often and use a more heat resistant fluid. AMSOIL or Red Line. 

[Arturoej8]

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Edited April 15 by Arturoej8

[Arturoej8]

On 3/23/2023 at 7:32 PM, rlcole321 said:

Better check and make sure you don't have a restriction in the trans cooler system, did the previous trans/converter failure dump metal into the system? did you flush thoroughly?

Yea it did bad converter caused the pump failure. Mechanic said he did I since then moved states so I’m kind of stuck with being able to return and have him check it out. The truck runs perfect I just don’t like the temperature it’s getting up to. Previously on the original transmission I pulled a 2010 Toyota Tacoma half accross the country and my Temp stayed at 200. I just ordered the mishimoto trans cooler I’ll be installing it next weekend hopefully that helps. 

[Arturoej8]

On 3/24/2023 at 9:54 AM, Grumpy Bear said:

Bottom line. Your truck is fine. Modify a bad habit stop idling for a half hour plus without a darn good reason and realize that when shutting down is not possible, like stuck in crawling accident traffic, this is what happens. Change fluid more often and use a more heat resistant fluid. AMSOIL or Red Line. 

I recently ordered a mishimoto transmission cooler and hope that helps. Also recently dropped the pan and replaced fluid and found small amounts of debris on the magnet. 
 

 

[Arturoej8]

On 3/24/2023 at 9:54 AM, Grumpy Bear said:

Bottom line. Your truck is fine. Modify a bad habit stop idling for a half hour plus without a darn good reason and realize that when shutting down is not possible, like stuck in crawling accident traffic, this is what happens. Change fluid more often and use a more heat resistant fluid. AMSOIL or Red Line. 

I recently ordered a mishimoto transmission cooler and hope that helps. Also recently dropped the pan and replaced fluid and found small amounts of debris on the magnet. 
 

 

[Grumpy Bear]

7 hours ago, Arturoej8 said:

I recently ordered a mishimoto transmission cooler and hope that helps. Also recently dropped the pan and replaced fluid and found small amounts of debris on the magnet. 
 

 

Looks fine. No 'glitter'. Some shmuck is always on the magnet and that bit of black is normal clutch wear debris. You will like your cooler.  

Edited April 16 by Grumpy Bear

[14LTZ-1LZ]

Did you update your transmission bypass valves to the "New GM" style when it was rebuilt? The old one opens at 194 degrees and the new suppose to open at 154.