I don't know if you would loose 15+ degrees....but wouldn't hurt to swap it out I guess.

I would see if you can get a replacement T-stat from wherever you bought it. I guess it's possible the 185* was put in the 200* box...or maybe you got a defective one? I would definately have it replaced.

Did the T-stat flange seal against the housing when you installed it? Was the sealing face of the housing clean and smooth with no corosion or anything that would prevent the T-stat from sealing? Was the spring somewhat hard to compress in order to install in the housing?

 

You guys that are not getting heat have to ck to see if the stat is closed against the housing, if not you have to drill the pin hole in the housing so the brass part of the t stat doesn't hit it

 

Everything looked good and clean. The thermostat was a bit hard to compress into the housing, looked to be flush with the housing.
Coolant is fairly new (1yr or so) the thermostat I took out was a motorcraft, and was changed when I did the coolant.
This is the third or fourth thermostat in 4yrs.
So far the only thing that works is blocking the radiator.
I must say, just changing the whole housing is nicer than wresting that spring.

 

Seriously? It don't fit right?
Mine looked like the stock one I pulled after I put the mishi one in. I suppose I can pull it out this weekend again and look though.

 

Got down to 18 last night and was 20 when I started the truck this morning. EOT and ECT were 33 when I started it. My ECT fluctuated every now and then from 198 to 200 on the way to work. EOT was at 204-205 (followed the ECT changes).

 

You should not drill the housing as this defeats the design of the housing. I almost did this myself, but dropped the thermostat housing into some hot water. It fit right into the housing no problem.

Even then, you it's been hot in your truck so it should've opened up and properly seated itself.

 

No mine is not blocked. Plugged in 4hrs before I leave for work. Temp was 78 let it idle till 100 and off I go.

 

There 2 factory housings,one the stat will not be able to close all the way nomatter how many times you cycle it. Ya gotta trim it a bit.

 

I have the 91 housing. That is the one everybody said works? The stat appears to be mounted right.
As I said earlier even with brand new factory stats, once winter hits, it runs cold, always has.
I thought about the cap more, and when I put the stat in Saturday, the truck was hot, and I relieved pressure off the cap, so the cap appears too be ok.

 

Maybe I got lucky but my housing is the 92 and had no problem.

2006 F350 4X4

 

Just ordered my t-stat from XDP. type in diesel10 in coupon code and get it for just over 50 bucks and that included FREE SHIPPING.

 

Hey guys,

Figured we would chime in on this thread, it has been quite some time since our last visit.

First of all, thank you to everyone who has ordered this thermostat and posted feedback. It is great to see how many folks are really enjoying this thermostat, and we are pleased to be helping keep you warm this winter!

As far as the housings are concerned. As others have mentioned, our thermostat will only functions with the later housing. Some early models utilized a different housing, which is not compatible with our thermostat. This is now noted on our site, as seen at the link below.

Ford 6.0L Powerstroke High-Temperature Thermostat, 2003–2007, by Mishimoto

Now, many folks here have posted regarding issues with reusing the stock o-ring when installing our thermostat. We always recommend replacing the o-ring when swapping this component. Doing so eliminates the chance of leaks, and this seal is certainly susceptible to degradation over time. After listening to this feedback from the forum, and our customers calling in, our team has decided to begin including an o-ring for replacement. These o-rings are now included with the existing units in our warehouse, and will eventually filter out to our vendors supply.

For those who purchased our thermostat and are in need of an o-ring, please contact our customer service team and we would be more than happy to send one out! We have several of these on-hand, and we are ready to ship them. I apologize that this component was not included when this thermostat was initially released.

Thank you again for all of the orders, enjoy the thermostat. Let us know if you have any additional questions!

Thanks
-John

 

After reading and seeing the reviews on in this thread I went ahead and purchased one. First run with it installed was this morning on the '06 CC. Outside temp was 37 when I started it and didn't pay any attention to what oil or coolant temp was on initial start. It sat idling for a little over 20 minutes as I waited for my son to get ready. Once we got in and ready to leave the coolant temp was 102 and oil at 99. Drove probably 30 miles total with 40% being highway. Truck was running close to an hour by the time I returned home and coolant temp only managed to reach 164 with the new Mishimoto 200 thermostat. Later on today I'll have to make the same drive in warmed temps to pick my son up and see if it climbs higher in warmer temps (supposed to by 62 today).

 

That's great The O-rings are included now.

This housing thing has me very confused though. All 2003-2007 6.0 motors take the same Ford thermostat. How can the same Ford thermostat fit both housings, yet the Mishimoto won't? Can you explain what happens if the Mishimoto is installed in the "old" housing? Pics would be great....

As you see here, and we've seen in other threads, several people are having problems getting temps close to 200 with the Mishimoto, and no one knows why. (look at the post right after yours)

 

I have both housings here at home. I drilled the center with a 3/8" drill bit to shave enough off so it seats fully. You have to do this or it WILL run cold. The other alturnitive is to get the housing that Misimoto recommends.