Thermostat operation
Fleet Mechanic
Joined: Jul 2013
Posts: 1,330
Likes: 65
From: 'Pitlock, Maine
Good point..I was just chalking it up to crappy new parts because "back in the day" we didn't have these issues, but I think this is the first vehicle I've owned where I see the temp to the single digit every time I drive it.
Anybody bought a thermostat that didn't drop after a few months and what brand? Think I'll search the web for a souper-douper billet piece with a tritium/unobtainium spring (hopefully blue anodized) lol. Honestly, I do think my truck pulls better and gets better mileage at 195* than it does at 180*.
Anybody bought a thermostat that didn't drop after a few months and what brand? Think I'll search the web for a souper-douper billet piece with a tritium/unobtainium spring (hopefully blue anodized) lol. Honestly, I do think my truck pulls better and gets better mileage at 195* than it does at 180*.
Lead Driver
Joined: Feb 2011
Posts: 8,241
Likes: 155
From: L.A. (Lower Alabama)
Coolant temp should stay below 215* towing or not. Above that it's getting dicey. You could bump that kind of temp towing in the mountains or other extreme situations (drag racing etc) but that's getting up there under normal conditions. I think the cooling system is more than adequate to keep up with the heat load and if your cooling system is in good shape 200* cruising shouldn't be a problem when you tow.
Before I replaced my coolers the oil temp was the issue. It was creeping up 235+ with coolant staying around 210 if I remember right.
Before I replaced my coolers the oil temp was the issue. It was creeping up 235+ with coolant staying around 210 if I remember right.
Hotshot
Joined: Apr 2010
Posts: 19,056
Likes: 236
From: Saratoga Springs,UT
Your Right about the Gauges
Iv never monitored a Vehicle close like this 6.0L
But my wifes Chev Popped a CEL for Thermostat few months Back running to Cold
found a P0128 {Coolant thermostat=Coolant temp below thermostat regulation Point)
It was A first Iv had a CEL for thermostat
Senior User
Joined: Aug 2011
Posts: 240
Likes: 0
From: Central arkansas
I got my truck in aug of '11 with 77k, changed the t-stat with a motorcraft in oct '12 127k and now have 177k and it is still hitting 192 everyday. I guess i've been lucky but hope it keeps going.
Certified Thread Hijacker
Joined: Aug 2001
Posts: 14,441
Likes: 59
Big difference between a daily driver seeing 20,000+ miles a year and another that sees 4000 every 12 months.
I know my 05 ran cool when I sold it, the temp needle would barely move in the colder months. But it had 170,000+ miles on it with original t-stat. I would guess the t-stat started to fail at about 135,000 or so.
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Hotshot
Joined: Jul 2005
Posts: 13,834
Likes: 25
From: Middle Tn.
Not sure if I have ever seen where you have posted how many miles your truck has and and how often you use it.
Big difference between a daily driver seeing 20,000+ miles a year and another that sees 4000 every 12 months.
I know my 05 ran cool when I sold it, the temp needle would barely move in the colder months. But it had 170,000+ miles on it with original t-stat. I would guess the t-stat started to fail at about 135,000 or so.
Big difference between a daily driver seeing 20,000+ miles a year and another that sees 4000 every 12 months.
I know my 05 ran cool when I sold it, the temp needle would barely move in the colder months. But it had 170,000+ miles on it with original t-stat. I would guess the t-stat started to fail at about 135,000 or so.
Senior User
Joined: Aug 2010
Posts: 216
Likes: 0
From: Duncan, OK
Thermostat shouldn't fail closed because as others have already pointed out, the spring keeps it closed. It can get weak, but it's not going to get stronger. In all the years I have owned and worked on vehicles, I have never had a vehicle overheat from a failed thermostat. I guess it's possible if you have a SEVERELY neglected system? You could get a build up that would cause it? I don't know, I've never seen one... not even convinced they exist. Anyone else ever had one stick closed?
Elder User
Joined: Apr 2005
Posts: 907
Likes: 2
From: Jackson, TN
It is my understanding that most thermostats are designed to fail open. I have replaced a few hundred over the years, and the only ones I have seen stuck closed have been on the 4.0l sohc engines.
Hotshot
Joined: Apr 2010
Posts: 19,056
Likes: 236
From: Saratoga Springs,UT
Iv had problems with everything except Motocraft
In my case the aftermarkets work fine till the end of a Summer then AT this time of year they run Cold and I would have to change again. Seams like they had a Life warrenty but I didn't want to have to change a Thermostat every year so Back to Motocraft
This was the second summer for my last MC and so far so good
Im thinking some of these folks that have repeated issues may have Cooling issues
Maybe there egr valve isnrt plugged in so the fan don't work right so it lets the coolant get Hotter before the fan Kicks On IDK
If it runs Cold then the spring is Weak I thinking the Heat plays a Huge role in this
Im thinking if the thermostat is Fulley open @ 218*f once you get Past that it Affects the Spring and just a Guess but anything over 225* is Likely do damage and making the spring weak
In my case the aftermarkets work fine till the end of a Summer then AT this time of year they run Cold and I would have to change again. Seams like they had a Life warrenty but I didn't want to have to change a Thermostat every year so Back to Motocraft
This was the second summer for my last MC and so far so good
Im thinking some of these folks that have repeated issues may have Cooling issues
Maybe there egr valve isnrt plugged in so the fan don't work right so it lets the coolant get Hotter before the fan Kicks On IDK
If it runs Cold then the spring is Weak I thinking the Heat plays a Huge role in this
Im thinking if the thermostat is Fulley open @ 218*f once you get Past that it Affects the Spring and just a Guess but anything over 225* is Likely do damage and making the spring weak
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Hotshot
Joined: Dec 2003
Posts: 15,368
Likes: 121
From: Stuttgart, Ar
I do know that with THIS new thermostat my truck warms up a LOT faster than it ever has previoiusly.
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vectrex
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Aug 21, 2011 01:11 PM