2017 GMC Sierra 1500 Transmission Cooler Recommendations

[Hexa Fox]

Greetings Gentlemen,

 

I was hoping you guys could recommend a transmission cooler for my truck above and give me some advice. From what I can see there is not a whole lot of literature available for the newer trucks. I remember always wanting an aftermarket transmission cooler for my old Silverado which I believe ran the notorious 4L60E or close to it. I know they were notorious for getting hot and failing, especially when putting them under load. To be completely honest I am not sure if my truck has the same transmission or a transmission from the same family or what. I am probably going to start looking under the hood today. However, I expect to see the one of the tiny radiators connected to the transmission just like before. 

 

Anyway I have never done this before and have a lot of questions, like what goes into it and what all I should add. For instance, I hear people talking about upgrading/calibrating the thermostat, adding a deeper pan for more transmission fluid capacity and other stuff like that. I was wondering how much of this other stuff I should worry about or if the main thing is the bigger radiator? I saw one that peaked my interest from Mishimoto but after I saw the price tag being close to $1,000 I was immediately turned off. Can I expect to pay this for all aftermarket transmission coolers or are there other more affordable solutions? 

 

I am interested because this truck will be used to tow sometime in the future. I plan on getting a tandem axle trailer on the smaller side 12' or 14'. So I figure going ahead and doing the upgrade now can only help extend the life of my oil and transmission even further. I occasionally towed a trailer with my old Silverado and I remember the transmission getting extremely hot even with the trailer being empty. So as always any advice and feedback is greatly appreciated in advance. 

[CamGTP]

If you have the 6L80e transmission just do the in-line thermostat mod. Remove the thermostat and flip the pill inside of it so the cooler is always open. It should drop your temps by 20-30 degrees easy.

[Hexa Fox]

21 hours ago, CamGTP said:

If you have the 6L80e transmission just do the in-line thermostat mod. Remove the thermostat and flip the pill inside of it so the cooler is always open. It should drop your temps by 20-30 degrees easy.

Do they put those same transmissions on these newer trucks? Does one of the codes on that sticker in the glove box tell me? 

 

I will Google the thing for the thermostat mod. Never heard of this. So are you saying if I do this mod I should not seek an aftermarket radiator for the transmission?

[CamGTP]

The 6 speed auto is behind the 4.3 and 5.3 engines in all the lower trims. The higher end trucks like the LTZ's and High Country's could get an 8 speed auto.

 

I don't know the RPO code but the easy way to tell is if your cluster goes PRNDM for 6 speeds and PRNDL for 8 speeds.

 

Yes, if you do that mod you really shouldn't need an aftermarket cooler. The stock thermostat in the cooler line wants to keep the temps between 185-200 degrees and if you flip the dealio inside the cooler thermostat housing it makes fluid flow all the time instead of waiting for the thermostat to open. Temps should drop an easy 20-30 degrees.

[WilliamBos]

MYC is the RPO code for the 6L80.  Another sign of the 6 is a trans dipstick, if it has one, it’s the 6.

[Hexa Fox]

7 minutes ago, WilliamBos said:

MYC is the RPO code for the 6L80.  Another sign of the 6 is a trans dipstick, if it has one, it’s the 6.

Thanks I will check out the stuff you guys mentioned. I already looked up a YouTube tutorial on how to bypass the thermostat like Cam mentioned. Also I looked at the Mishimoto transmission coolers again and they have a couple for my truck. I was looking at a "performance" one that was $800.00+ and the one that I have seen others recommend is around $400.00. I think it is still heavily overpriced but much more affordable than I originally thought. 

[WilliamBos]

1 minute ago, Hexa Fox said:

Thanks I will check out the stuff you guys mentioned. I already looked up a YouTube tutorial on how to bypass the thermostat like Cam mentioned. Also I looked at the Mishimoto transmission coolers again and they have a couple for my truck. I was looking at a "performance" one that was $800.00+ and the one that I have seen others recommend is around $400.00. I think it is still heavily overpriced but much more affordable than I originally thought. 

Look for another brand, ‘mishijunko’ (as my friend calls them) does not always like to support what they sell, quality seems hit and misd.

 

Look at a cooler from a trans company, such as B&M.

 

I thought the V8 trucks had an external trans cooler?

[2018GMC]

I've towed 4k lbs across desert with 110 outside temps and my 8l90 trans temp was 190 - 215. My truck is stock 6.2L max tow.

 

Can I mod the trans thermostat like the 6l80 or just leave it be?

[CamGTP]

The 8 speeds I don't think have the cooler on the transmission line like the 6L80e.

[Hexa Fox]

5 hours ago, WilliamBos said:

Look for another brand, ‘mishijunko’ (as my friend calls them) does not always like to support what they sell, quality seems hit and misd.

 

Look at a cooler from a trans company, such as B&M.

 

I thought the V8 trucks had an external trans cooler?

I just went to the B&M website, when I put my truck information it says there is no compatible items. I thought about going with another cheaper solution like Tru Cool or something but I have watched two YouTube videos and both of them had trouble with it leaking. I am sure they got it figured out in the video but it immediately turned me off. I think the big marketing advantage for Mishimoto is you do not have to cut factory lines for installation. The most invasive thing I think you have to do is drill some holes behind the grill for lines to come through. 

 

In my opinion it is still a ripoff at $400.00 though. It is literally a piece of aluminum that you bolt behind your grill. I guess if it a better job of keeping your transmission cooler I guess it is worth it. Not trying to stroke any particular brand or anything because I know very little when it comes to aftermarket transmission coolers. 

[Ozer]

I had mine deleted when it was rebuilt and it runs nice and cool, its even fine in north east winters.I had no issues, been over 12k miles now.

You can DIY it (youtube it) or there are delete kits out there for around $100 which is what i got.

[truckguy82]

The oem cooler is fantastic, unless you’re towing 12k lbs up grades in the desert, or racing your truck on a circuit track, it’s unlikely you need a transmission cooler.

[Hexa Fox]

6 hours ago, truckguy82 said:

The oem cooler is fantastic, unless you’re towing 12k lbs up grades in the desert, or racing your truck on a circuit track, it’s unlikely you need a transmission cooler.

All I know is my old truck had the 6L80E and it got super hot when towing just around a ton. Like if I had my windows rolled down you could feel the heat coming up into the cab. I changed the transmission fluid on it around 95,000 and I think it did more harm than good, but it still slips a little. 

[Hexa Fox]

8 hours ago, Ozer said:

I had mine deleted when it was rebuilt and it runs nice and cool, its even fine in north east winters.I had no issues, been over 12k miles now.

You can DIY it (youtube it) or there are delete kits out there for around $100 which is what i got.

So what exactly does deleted mean? You mean you are bypassing the thermostat? Also by a kit you mean you would get like a new thermostat assembly and just change them out? 

[Ozer]

On 5/8/2020 at 7:30 PM, Hexa Fox said:

So what exactly does deleted mean? You mean you are bypassing the thermostat? Also by a kit you mean you would get like a new thermostat assembly and just change them out? 

I cant remember what kit the shop got but you tube the delete and you will see how its done. There are few ways to do it.

Delete means the trans fluid circulates and starts to get cooled soon as you start the truck vs reaching the thermostat temp and then circulating.