🔧 Motorcraft Thermostat Assembly (P) - Part RT1234 Review

I installed this thermostat on my 2004 Mustang GT. I tested it with an OBD-II reader for accurate readings and the thermostat opened right up at 192 degrees, which is the default setting for this engine. With my engine, it rises to about 212 degrees over a longer period of time when idling. After that it stopped moving and cooled down to about 200 during the ride. I had no problems with overheating or long warm-ups.

The best thermostat ever! Not really. It's a room thermostat. It opens when it gets hot and closes when it gets cold. It also fits my 2000 Mercury Grand Marquis with 4.6 engine. What else can be said about the thermostat? The only thing I can add is to remove as much air as possible from your cooling system when replacing. The thermostat housing appears to be the highest point in the cooling system, so it takes some effort to get all the air out. Completely fill the upper radiator hose with…

The 4.6 liter engine runs better with this 192 degree thermostat. After replacing the 180 degree thermostat fitted to the car by the previous owner, I noticed an increase in gas mileage (+3mpg) and a noticeable reduction in engine noise. The engine no longer hums and the valves are now almost silent. The 4.6-liter engine likes to run a little warmer - Ford designed it that way. Do a little research on the subject and you'll see why. Do yourself a favor and buy the right thermostat for your 4.6…