These are my initial impressions of the Mishimoto MMTC-GMP-TBV transmission cooler thermostat, and some other interesting info. I posted before about the Revmax bypass I installed years ago which provides full flow to the trans cooler at all times. While not harmful, it’s not ideal for winter use in the north. So I looked into other options that retain a thermostat but at a lower activation temperature, and with better flow.
First I started by looking at the factory TBV, Mopar part number: 52014762AA. I pulled that part number up and find that it was originally used on 3.6 powered Charger, Challenger and 300!
Yep, they stuck a failure prone, high temperature and low flow Pentastar transmission thermostat in our TRX!!!
While I find that “engineering decision” incredibly stupid, it was actually a good revelation. Because that’s how I found this Mishimoto…simply by looking for that application instead of the 8HP95.
Onto the review. The Mishimoto is actually really well finished and seems to be a quality part. Comparing it to our factory 3.6…I mean 6.2…TBV, the difference became clear. The factory TBV is choked down to 1/4” at the cooler outlet fitting. So even when the thermostat opens eventually, flow is restricted. 1/2” lines mean nothing. The Mishimoto is wide open after the thermostat.
View attachment 145705View attachment 145706
Install was the same as the Revmax. Easy but not comfortable. Have a nitrile o-ring kit handy because yours may be damaged. The Harbor Freight kit had o-rings that were a little thicker but work fine. No leaks.
View attachment 145707
The fitting at the bottom allows you to drop out the thermostat and install the included bypass if you want full flow 100% of the time. I haven’t tested that yet, but it seems like it’ll be pretty tight to get out of there while leaving the unit in place. We’ll see. So far I am happy with thermostat temps but this is a very early review.
I just did a 45 minute drive after install. Mixed city and highway. Trans got up to temperature quickly and stayed very stable. Running down the highway it was easy to detect when the thermostat was opening. Trans would hit 151*, drop to 147, 149 and then repeat when hitting 151 again. Some WOT pulls brought temps to as high as 158* but as soon as I backed off it would drop back to that 150-ish range. So while this thermostat is listed at 160, ostensibly the same as factory, it runs MUCH cooler than factory. I can remember seeing 190+ on similar length highway trips with the factory TBV. And for more context. With the Revmax in this weather I’d see probably 125-ish.
View attachment 145712
So overall I think it splits the difference between the factory part which is a piece of shit, and the Revmax which may be too racy for some. Here on eBay they have a coupon code that brought it to under $150. A bargain in my view. With warmer weather coming I will add more thoughts but initial impressions are positive.
Mishimoto has identified a common failure point in the transmission cooling system of your 2012-2023 Mopar: the thermal bypass valve. This component acts as a thermostat, restricting fluid flow to the external transmission cooler based on temperature.
www.ebay.com
Note: Mishimoto also sells one that’s cheaper and silver in color. It has “FF” at the end of its part number and doesn’t have a thermostat. If you want a cheap version of the Revmax it’ll work but not what most are looking for. The one in my link has the thermostat installed and includes a bypass if you want to install it down the road.
Summer 2025 heat update: Even with ambient temps approaching 100* in traffic, this thing maintains temperature below 180* easily. Perfect.
