Your thermostat is probably stuck open. Replace it with an OEM Motorcraft version, not aftermarket.
Reviews of Motorcraft thermostat
31 vote
I replaced the thermostat from a non-OEM to Motorcraft about a month ago, and the only difference has been the speed at which the dial moves from higher temps to its normal positon.
The Motorcraft thermostat sounds promising though, never have an issue with genuine ford parts.
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 bought a Motorcraft thermostat from the Ford dealer for my Crown Vic and it ran about 20 degrees cold.
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’ve had a Motorcraft thermostat fail after 100mi on my Ford
Make sure you use the motorcraft thermostat.
Go with the Motorcraft thermostat as it has a rubber seal on the outside edge.
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What we know about Motorcraft thermostat
The brand is registered in USA. Official website: https://parts.ford.com/.
In March 2026, PartReview users have a mixed opinion of Motorcraft thermostat.
PR Score — 74 out of 100, based on 10 reviews and 31 vote. 7 positive reviews, 1 neutral review, 2 negative reviews. Average rating — 3.9 (out of 5). Vote balance: 23 up, 8 down.
In the ranking of the best thermostat this part is at position 8, behind OEM Audi and OEM Honda , but ahead of OEM BMW and Duralast.
Users also evaluated the qualities of Motorcraft thermostat:
- Slow warm-up - engine takes a long time to reach normal temperature - rated positively. 4 points out of 5.
- Overheating - temperature gauge rises quickly or fluctuates - rated positively. 3.5 points out of 5.
- Cabin heat - heater blows weakly or becomes too hot at the wrong time - rated positively. 4 points out of 5.
Thermostat Motorcraft in car-specific ratings
See which car brands and models owners choose Motorcraft thermostat for. Below are car-specific ratings where this part is in the Top-3:
- Motorcraft ranked #2 for: Jeep Cherokee .
Thermostat Motorcraft in comparisons
There are 14 comparisons of Motorcraft thermostat with other manufacturers on PartReview.
In particular, see which thermostat are better: Duralast or Motorcraft, AISIN or Motorcraft, MotoRad or Motorcraft, OEM Nissan or Motorcraft, OEM Mazda or Motorcraft .