Ford Powerstroke Diesel Forum banner

Coolant Temp/Possible Sticking Thermostat

5K views 7 replies 3 participants last post by  Bassdo 
#1 ·
Hey everyone, I just put a scangauge on my 2011 and noticed just recently that my temp will steadily climb up to 200 degrees and then drop down to 188 in a matter of a few seconds and stays there in city, drops to 186 at a stop and highway 190 to 191 in 100 degree temps here in AZ. Is that normal for this motor to warm up like that or is my thermostat sticking and should think about replacing it? Thanks for any help.
 
#2 ·
During warm up time I see the ECT run up pretty fast, once EOT gets to normal ECT usually goes to floating as the tstat opens and closes. I say that is normal. EOT is directly related to the operation of the motor. Running unloaded in town, it's not going to get too much over 200-210*, towing heavy or loaded heavy it's going to be higher and stay there.
 
#3 ·
South texas can have comparable temperatures, but I see my coolant from cold run up to 190 then the 1st tstat pops and it falls back to 179, and then it'll be 179-183 running in town or at a stop, and around 185-189 on the highway. EOT always 10-15* higher than ECT when warmed up.

My 2nd stage tstat in the primary loop never pops unless I'm towing, it seems.


anything below 70* ambient and this truck takes forever to warm up.
 
#4 ·
Good info. My truck runs 188 consistent. It warms up pretty slow. Not super slow though. But it hits 200 degrees and then drops to 188 degrees within a few seconds. I have ever noticed it hitting 200 before. The other day I looked over and had only been driving maybe 5 miles in 75-80 degree weather at 60mph and it was at 200. Made me say wtf and then it dropped straight to 190 and then 188 and stays at that the rest of the time. Highway in a 105 degree weather at 75mph it runs 191 degrees. I guess I better just replace the thermostat to play it save. It's cheap and easy to do. Easy insurance since I tow a big 5th wheel through 7% grades. Thanks for the input guys!
 
#5 ·
well, when the thermo pops the first time, it floods the coolant passages with cold coolant from the rad that hasn't been circulated through the block yet, explaining the sudden drop from 200 to 180 (at the sensor, mind you).


Check your coolant level before you go replacing stats though, you may have a mystery coolant leak like so many of us do.
 
  • Like
Reactions: HeavyAssault
#6 ·
Coolant level is good. That is the first thing I checked. The OEM thermos are 189/194 so I figured that I should not be reaching 200 on warmup ever. Maybe my 189 side is stuck closed? Either way, from what you guys have said, I should probably just play it safe and replace it.
 
#7 ·
The stock hi-temp stats actually pop first at 194*, and then at 201*, give or take a few degrees (wax), according to the 6.7 tech manual. So, maybe your 1st stage is stuck closed...thermostats stick sometimes anyway.
 
  • Like
Reactions: HeavyAssault
#8 ·
Oh my bad. I was also looking at the low temp stats and guess I mixed them up. So you think my thermostat is acting normal? I guess it could be possible that the 194 side is sticking hence why I am hitting 200 before temp drops to 188
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top