Now I don't feel so bad going with OEM, I see 192 to 197 as an average here at 85 plus degrees out. It's been over a year on my OEM, deltas 2-3 degrees at 65/70 over 10 miles. A few months back I was driving her very aggressive and saw 7 degree deltas, I even gave Razzi a call while on the hwy. lol.... But that was over 20 miles averaging 80 plus with occasional wot burst to north of 110mph, Razzi promised I'd be ok lol... He was right!

 

Im holding out hope mishimoto comes out with a 192 or 195 tstat. I'm keeping the 200 for fall and winter but would be nice to not have to change. If they make it I'll buy it.

 

I'm running 200 to 204 ECT in ambient temps between 60 to 85F. Generally running unloaded, though.

I'm more concerned about the deltas. EOT is running 9 to 12 above ECT.

Is there a thread somewhere discussing appropriate values for deltas as well as countermeasures?

Rory

 

There are plenty on here. You're still good but keep an eye on it. The test is fully warned up, 65mph on flat ground for 30 minutes. Spread should be no more than 15°. No countermeasures once the cooler starts plugging other than doing a proper chemical flush the replace oil cooler. Coolant filter now may buy some time. Also that spread may be your norm--hhas it been climing? Some have a pretty decent temp split and have had the same for years.

 

Good Evening,

I have been reading several of the pages on this post and will be ordering my new t-stat this week and hopefully replacing this weekend. I have seen where some have seen lower delta separations once the new t-stat is in place. Currently I am having ECT 185-205 depending on the day and ambient air temps. I normally have a 14-16 degree difference between the ECT and EOT when running 1950 RPM (about 65-70mph) with no load. For those who have already replaced their t-stat with the new 200 what were the delta's you were seeing before the t-stat was replaced?

When pushing the Beast (04 Ex, 6.0PSD, 134K miles) over 75mph, delta's go up to 18-22, again with no load. I know an oil cooler replacement will so be in order, but that will go into another thread.

Thanks,
Jeff

 

My ECT and EOT are running 1-4 difference before and after the install, only thing is my normal temps are now 200-204. Yesterday was 95 degrees ambient, temp is 200-204 just like they should be, split still 1-4 from ECT-EOT.... mileage is up consistently 1-2mpg since install. About 10 days ago did a 400 mile round trip, hit 19.9mpg average with a 4-wheeler in the back at 70-75mph average.

 

I've been following this thread from the beginning and have a question that has been on my mind for a while... Many here have noted the positive results they've gotten with the Mishmoto thermostat lowering their deltas. And of course this is great! But when we see a higher than desirable delta, this is a sign of problems brewing, i.e: a clogged oil cooler, correct? So... If we run the engine at a higher temperature, and our delta decreases while running at this higher temperature, have we improved what was wrong with the engine, or have we just made a symptom disappear so that we are more comfortable and no longer feel that we must soon address a major problem? Sorry, just thinking out loud and wondering. Thanks, and good luck! Mike

 

Exactly. I think the injectors cause the oil to run a certain temp when everything is up to operating temp. But when the coolant is lower than what the oil is, by quite a bit, you will see higher deltas. As we raise the coolant temp, we see lower deltas because we are getting closer to what the oil would be running without help to cool it. I think the Ford test (65mph, 30 minutes, etc) would be with a coolant around 192 degrees. I expect that if Ford had anything to do with it, the delta would be more like 12 or less if running 200 to 206 coolant temps.


I also question the 65mph part of the test. My truck runs over 2k rpms at 65 mph where a 3.55 gear would run much lower. I have questioned the use of speed instead of rpm. I think we should be looking for around 1800 rpms when doing this test, but that is just my opinion.

 

Just came back from a 700 mile round trip of bringing the boat up to the cottage and watched the Scangauge to see and share what the results would be with the 203 thermostat. Averaged about 2000 rpm(70-75 MPH) and the boat weighs in at 4000 lbs plus trailer. The Ex was loaded with six people and food and gear etc. Outside temp was 84 F.

202-204 ECT and 210-212 EOT

I found the drive back was pretty much the same but the trailer was empty. I did notice that it took some time getting to the 210-212 EOT. It would sit at 208-209 for quite a while.

The Ex has a newer oil cooler in it and Shell Rotella coolant. It does need an oil change and I run Shell T6 oil.
Overall I have been impressed with this thermostat and would recommend it. I did have some lingering doubts about using a hotter thermostat in warmer temperatures.

Hopes this helps somebody.

Rob

 

IMO, very well said!

 

Finally able to get the Excursion out towing the camper on a trip longer than 10 miles this past weekend. With the 200 degree Mishi thermostat I ran between 204 and 215 most of the day towing 10k in 85 degree weather. A couple of large hills ran the coolant temp up to 220 and quickly pulled back to 212 when the fan kicked in hard and loud. Oil temp max was 232 when the coolant hit 220 but normally hovered around 9 degrees above the coolant temp.

I'm going to stay with the Mishi and keep a really close eye on the temps. Longer trip planned for August in what should be hotter temps, may go ahead and throw the cooler thermo in for that.

Mishimoto, please come out with a 195 thermo, I'd be good for all year instead of looking at swapping twice per year!

 

So where is Mishimoto in all this? They've been awfully quiet....

 

I want to thank everybody for keeping this thread updated.. I am waiting for the 2nd (or 3rd) generation of these things to come out AND to SUCCESSFULLY go through the "FTE 6L field test" process (courtesy of you FTE volunteers!) before I will consider one of these for my 6L. IMO, for 2x the stock price + "assembly required" AND as simple as it is to remove/install a STOCK t-stat I am sticking with the stock t-stat.

 

I can understand this. They seem to have moved on to other forums of different brands. I have waited to install my new Motorcraft thermostat for a few months. My original 03 stat is still holding warm enough for me in the winter months. I know there are some improved aftermarket parts but I always try to stay with the Motorcraft parts.

 

I think I'm going back to OEM. Not my original stat, but the new Motorcraft one that came when I ordered the correct housing for the Mishi. Fan clutch DC hasn't bumped up from zero yet (too cool in TX with all the rain I guess, ECT never goes over 203*f really), but at 194*f the fan speed bumps from ~800-900 to ~1300-1400rpm, even with engine RPM constant around 20k and MPH constant around 70mph. MPG fallen off to 14.5 down from 15.5 over 2k miles, only change was the stat.

Plow clutch causing issues maybe?