Hello all,

2007 H3, stock, 243,000 miles, transmission fluid just changed, and changed every year since I've had it (~40,000 miles between changes).

What would be the normal acceptable transmission operating temperature for an H3? I have been tracking my temps while driving lately, and while driving mostly highway miles (70-75 mph), the transmission will consistently get up to 206 degrees. This is also the same exact temp the coolant is at. Driving around town the temps will stay lower, say 180-190.

I recently went fishing about 2 hours away, and while towing my 16' boat (1,000 lbs on the high end), I saw my temps get to 230, and maybe a few degrees higher (coolant was still 206-210). I've tried different driving techniques, like running in 3rd when 55 mph or lower, and trying to keep the torque converter locked up by slowing down going up hills, but the temps still get higher.

During one morning trip, outside temps were 55 degrees, and while pulling the boat the transmission was at 190 after 2 hours. Trip back during the day, however (78 deg), I saw just over 220.

Do these temps seem normal, or are they high? I'm wondering if I have a problem going on with either the trans or the cooler.
Note that I have no other issues with the transmission (slipping, etc.)


As an aside, does anyone know where the temperature is read in these transmissions? Are the pre or post cooler? I'm curious if this is pan temp or internal temp.

 

What are you measuring Trans Temp with?

Seems pretty normal to me with the miles you have on it.

The coolant temp from the OE Coolant temp sensor is at the motor exit so it is warmer than the coolant temp at the radiator exit.

 

Thanks for the reply Doc.

I'm using a cheap OBDII bluetooth reader plugged into the OBDII port, and then using Torque Pro on my phone. The trans temp is using an add-on GM PID, specifically PID 221940 using an "auto" OBD header.
I have a bit more professional reader when I need to read other codes (actually recommended by this board), but for real-time data this is what I use.

I'll keep monitoring the temps. I know I have a few miles, and it's only a mater of time before I need to refresh things.