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I have a 2015 FXT that I bought recently with 90K miles on it. Everything checked out on inspection. I added a Cobb Stage 1 OTS map and did Danoz fix to prevent boost leak, the vehicle has no other performance mods.

I’m in AZ and I noticed the transmission would run hot up to about 230F on crosstown trips (10+ miles, 65-75 mph freeway). Ambient temps 105-115F. Engine and coolant temps typically stayed 210-220F. I decided to change the trans fluid and add a transmission cooler.

I dropped the trans pan, changed the filter, and flushed the old fluid. Refilled with Amsoil CVT and added a Hayden 697 Trans cooler. At first I bypassed the stock trans cooler, but the CVT temps seemed to rise quicker than before. Re-routed in line with the stock cooler (stock cooler first, then the Hayden, then back into trans). I made sure CVT level was correct (perfectly level, at 105F when I topped it off) This seemed to help it stay cooler a lot longer in town.

Yesterday I took a road trip from Phoenix to Flagstaff with a typical family load (2 day trip, 2 passengers and bikes). The drive is uphill most of the way and Ambient temps were 90-100F. Halfway through the trip going up some long uphill at 75mph the AT dummy light came on and the CVT temp hit 266F! Slowed down immediately, turned off ac and accessories and cranked the heat. Engine and coolant temps dropped quickly, trans fluid was slightly slower to drop but I got it below 230 in about 3 minutes. We had to drive uphill sections at or below the speed limit to keep it under 230F the rest of the trip.

So what is causing this? Could it be that the trans fluid isn’t circulating properly to the coolers? I’m at a loss here. This is absolutely abnormal. I have a 2018 Outback and have made this trip many many times at high speeds fully loaded and never had an overheating problem...
Thanks for any suggestions!
 

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2015 XT Touring CVT
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what are you using to monitor your trans temps? did you follow the trans refill procedure with bringing it up to temp and going through the gears etc. wondering if you have air in the system so its not cooling correctly.
 

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Discussion Starter #3
The Cobb Access Port reads cvt Temp from the ECU. I followed the procedures exactly - level on stands, CVT temp was 105F, filled until it started draining, ran through gears twice, added more fluid until it drained out again.
 

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what are you using to monitor your trans temps? did you follow the trans refill procedure with bringing it up to temp and going through the gears etc. wondering if you have air in the system so its not cooling correctly.
I’m hoping it’s as simple as air in the system or somehow low fluid level. I’ll check when I get it back home. Fortunately it’s downhill most of the way and I can monitor the temps closely.
 
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