It is now that time where we are entering the summer months and its getting above 80 degrees outside. The standard operating temperature of the 2018 Lincoln Navigator L seems to be between 210-220 degrees which has always seemed too hot to me. Time after time Ive been shown charts and data throughout my entire life which demonstrate that temperatures like that always lead to premature failures like transmission failure. So I decided to try out the Reische Performance 170 degree thermostat for Ford Ecoboost engines like in the F150.
There were a few tricks to getting out the thermostat. The first step is to drain the coolant and there is a reddish drain knob under the vehicle on the drivers side. Its between the left frame rail and tire towards the front. It stands out as its the only red knob under there. If you turn that knob and have the coolant reservoir cap open it will be coming out fast. The other tricks to getting out the thermostat was the gymnastics under the hood. Squeezing my hand into the tight space of the engine to turn little bolts and not losing the tool or the bolt in the process...not fun. At one point I had to remove a large tube on the air intake to gain access but then it took a long time to figure out how to get it back on as more underhood gymnastics was required. When I say not fun, got very dirty, got a few small cuts with blood everywhere and took a lot of time trying to figure out how the air intake hose went back on.
When I was done reinstalling everything I added coolant. This was a process because I filled the reservoir up to the top but as the engine warmed up it seemed to need a bit more. So had to monitor the coolant level for a bit. I poured the old coolant with a funnel into the empty coolant bottles that I used to pour the new coolant in. It was about 1-2 bottles of coolant used to refill it. I dont think all of the coolant comes out when you turn that red knob but about 5-6 quarts.
I tested it out by driving around for about 20 minutes with full air condition and the vehicle in "Excite" or sport mode with the all wheel drive engaged. Then doing some spirited runs around town. I was able to get it up to 203 degrees maximum. Later on when I was cruising on the highway I found I was able to sustain about 190 degrees. It was 86 degrees out by the way. Usually on such spirited runs I would get the temperature up past 220 degrees easily.
From what I read in order to get the maximum benefit from this thermostat I need a "tune" which would set the fans to engage at different temperatures. However, I found that I was getting enough benefit as it was without the "tune". Operating temperatures were quite a bit lower.
The story does not end here. Im going to monitor the fuel efficiency of the setup and I might or might not keep it depending upon what I experience mpg wise. There is a Motorcraft 180 degree thermostat available and you can find that one by ordering the thermostat for the 2019 Lincoln MKT Livery. I recently did a coolant flush on that one and put in a new thermostat and found its exactly the same size as the one in Navigator but its set for 180 degrees.
Let me explain something about thermostats. When the thermostat is rated for 190 degrees it does NOT fully open at 190 degrees. It will start opening and then somewhere north of 210 degrees is when it fully opens. So the 170 degree thermostat will start to open at 170 and then fully open somewhere above 190 degrees.
The Reische Performance thermostat has been out there for years and I found forum posts some 6 years old. I think this modification is a no brainer and should be done right away with any Ecoboost engine. The only question I have right now is about fuel economy with this setup...another question is how will it do in winter and maybe I should switch to the 180 or 190 when that time comes. A lot of people seem to be in agreement that an operating temperature above 210 degrees is not a good thing. 180-200 is more preferable for reliability. I have no data or studies on that but it seems to agree with what Ive heard over the years about heat and engine/trans longevity.https://www.reischeperformance.com/index.html#anchor