Thermostat OEM Nissan or Motorcraft

I used a motorcraft RT-1139 thermostat. Comes with a jiggle valve to help bleed air already installed and cost me 8 bucks. You won’t find any place that says they fit other than some forum posts but they do indeed work, I installed one on my MJ with the only issue being me not refilling the radiator after dumping all the coolant.

I requested they use only Motorcraft thermostat, because I knew there was a part # update. Threw the updated Motorcraft one in and it solved the issue.

Soon as i bought Motorcraft all was normal again

I had this exact issue with 3 aftermarket thermostats that were opening too early. Bought one from Nissan and my temps went back to normal

OEM Nissan, but slightly more conservative with cooling.

Replacing the Thermostat with a OEM part has solved the issue (with coolant flush) from a dealership.

Make sure you use the motorcraft thermostat.

Go with the Motorcraft thermostat as it has a rubber seal on the outside edge.

After reinstalling an OEM thermostat, I am very happy to say my high temp issues have been solved!

I’ve had a Motorcraft thermostat fail after 100mi on my Ford