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200* Thermostat

9K views 22 replies 13 participants last post by  Weberman3 
#1 ·
With steadily cruising on the highway at 65 my ect is around 182-184* with my eot around 195-200* and the factory thermostat is rated at 192. Which makes me lean toward I have a bad thermostat. Also I am located in Missouri and our winters can get down in the single digits and summers in the high 90's and low 100's. So my question is, is the Mishimoto 200* high temp a better choice than factory?
 
#2 ·
I'd say that you are fine either way. By all accounts, the pan temp is 10-25F above the measured EOT. It's good - but not necessary - to have EOTs around or above 212 to purge the water and water-based contaminants. Either stat would get you there without at all approaching the defuel temp (measured EOT=254F) or anything that would bake the oil.

That said, if your deltas stay consistent after a 200F stat swap, you will be sitting with a measured EOT around 218F and a pan temp closer to 240F. That is perfectly fine, IMHO. Synthetic will take that all day long. ...but, if looking at that temp on your gauge is going to cause your head to explode, you are better off with the 192F.

That's my two pesos...
 
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#3 ·
First..
That's my two pesos...
This is America.

Second. I have the 200 and also in Missouri. There was no problem towing 6k and AC on. I think ECT was about 202 max and EOT was 215.
I did the Mishimoto for higher temp and it seems the stock ones need to be replaced frequent so I'm trying it and seeing how long it lasts.
 
#6 ·
Mine is the same way. Sometimes mines is in the mid 170s during normal cruising. Im planning on installing a Mishimoto high temp thermostat this weekend.
 
#8 ·
I also have the 200F coolant stat and cruising down the highway at 75+ my coolant temps are 200-205F.

The 15F delta still applies so no more than 15F increase over the coolant temp.
 
#10 ·
First off welcome to the forum! I have been thinking of switching to the mishimoto 200F thermostat for a while..however i have heard that the oem one is the only one on the market that "fails" in the open position. My truck has been through 2 oem thermostats in less than 3 years,90% of the time is sitting parked in the driveway. I imagine the oil will be just a few degrees warmer with the mishimoto thermostat so you should be fine.
 
#11 ·
The OEM can fail closed also it just depends how it fails.

Thermostats can fail, and depending on the failure point it will cause the thermostat to fail either open or closed. Example: if the return spring fails, the thermostat will be “open”, or if debris gets trapped where the valve seats, then it will be “open”.

If the wax inside the thermostat fails, it will be stuck in the “closed” position. When this happens, the truck overheats to a point where it builds up a lot of pressure in the radiator hoses and causes them to blow off or burst (think of a movie with smoke coming out from the hood).

Both failures are not ideal, but it does happen. If a thermostat failure does occur, please contact our Customer Service Team to begin the warranty process in order to have the thermostat replaced.
 
#12 ·
Definitely sounds like a failing factory thermostat. They tend to produce a lower activation/operating temperature when aged. I think you will find our 200 degree unit quite helpful in retaining reasonable ECT in the winter months. Let me know if I can answer any specific questions about the thermostat.

Mine is the same way. Sometimes mines is in the mid 170s during normal cruising. Im planning on installing a Mishimoto high temp thermostat this weekend.
Great! Let us know what you think once it is installed.

The OEM can fail closed also it just depends how it fails.
Very true!

-John
 
#13 ·
What's the advantage of one over the other? Local ambient temps? I'm going to be changing mine out soon. I want to explore all options.

Thanks
 
#14 ·
Truck use and environmental conditions should dictate your thermostat choice. If you are hauling large loads or towing heavy equipment in a hot ambient environment, the high temperature unit may not be the one to purchase. This will raise the coolant recovery temperature a bit, which under very stressful driving conditions could be a negative impact. A lower temperature unit will have a lower recovery temperature which could be helpful when towing and passing through undulating terrain.

If you are in a cooler climate and are not performing highly stressful driving, the high temperature unit will improve warm-up speed, in-cabin heat, and will even impact fuel mileage. A few of our customers have also reported the 6.0L seems happier at the higher temperature.

The choice just comes down to the driving conditions and environment.

Hope that helps!
-John
 
#15 ·
Here is my update. Took about 15 minutes to get it in. Just got my rachet, an extension, a swivel and a 10mm. took the bolts out of the housing and took the clamp loose on the upper hose and pulled the hose out. Then opposite on the install after boiling the new one in the housing to make it seal. The truck warms ups faster, seems like it has a tad more pep in its step and my mpg's have gone up a couple. My ect stays around 198-200 and my eot stays around 208-210 while cruising at 70 on the highway. I am loving it so far and would definitely recommend this thermostat!
 
#17 ·
I don't have a problem with mine had it since late September early October and run 200-210F down the road but I do have a blown head gasket so I can't keep the correct amount of coolant in the truck.
 
#18 ·
I live in Maine...a hot summer day is 80ish and a cold winter day is -20ish I installed the 200*mishi this spring and so far its the cats meow, 200/202 coolant and eot runs 6/8 hotter. Highest I've seen is a 12 degree split when towing my 34' T/T. As for the winter temps I'll have to wait and see, but if it holds as true as it does in the heat it'll work fine.

...with my oem after a little time they all seem to start losing temp and the oil was a couple of degrees hotter than the water usually around 8/10 split. I can't explain why the oil /water delta narrowed with the hotter Tstat but I know it did.
 
#19 ·
how does the lifetime warranty work with the 200 mishi? is it a true lifetime, if it fails do they send a new one without having to wait for the return process thru snail mail???? i believe that you can buy 3 ford oem thermostats for the price of the high temp mishi....... mishi please respond, i''d be interested in the higher temp thermostat living in western wy where temps outside get below zero routinely for months on end. thanks
 
#23 ·
The way it works is that you talk with them, fill out a few questions, then attach a photo of your receipt and a photo of whatever item you want to get warrantied.
 
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