Thermostat operation
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Joined: Dec 2003
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From: Stuttgart, Ar
Thermostat operation
I'm not an engineer but I've been fooling with engines for a long time and since this question seems to come up a LOT maybe someone a lot more knowledgeable than myself can answer these questions.
Why do our thermostats seem to fail at such a seemingly high rate? I'm on my third in 2 years (all Motorcraft)
Why does the temperature always seem to go cooler instead of hotter when they fail? I have rarely, if ever seen or read of the temps going to the high side.
From all my Google searches there is nothing special about our thermostats that say they fail on the "safe" side, i.e. they don't fail open. Everything I can find says that they fail either open or closed. Is there something engineered into the cooling system that "forces" the temperatures to go to the cool side if the thermostat fails?
Why do our thermostats seem to fail at such a seemingly high rate? I'm on my third in 2 years (all Motorcraft)
Why does the temperature always seem to go cooler instead of hotter when they fail? I have rarely, if ever seen or read of the temps going to the high side.
From all my Google searches there is nothing special about our thermostats that say they fail on the "safe" side, i.e. they don't fail open. Everything I can find says that they fail either open or closed. Is there something engineered into the cooling system that "forces" the temperatures to go to the cool side if the thermostat fails?
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Joined: Feb 2009
Posts: 1,170
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From: Moyock, NC
I recently changed my t-stat when I performed a system flush, changed the oil cooler, and deleted EGR cooler.
With the new t-stat I'm pressed to get it up to 192...generally stays between 188-190 with oil at 196-200.
I understand that the coolant is cooler since EGR cooler is gone and no longer heating the coolant from exhaust gasses.
But, I wonder if my brand new t-stat is slightly open....or are my temps normal?
With the new t-stat I'm pressed to get it up to 192...generally stays between 188-190 with oil at 196-200.
I understand that the coolant is cooler since EGR cooler is gone and no longer heating the coolant from exhaust gasses.
But, I wonder if my brand new t-stat is slightly open....or are my temps normal?
Lead Driver
Joined: Feb 2011
Posts: 8,241
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From: L.A. (Lower Alabama)
My experience is similar. 2 Motorcraft and 1 Stant so far. They all seemed to make 190* pretty quick when they're new and fade to a sluggish 180* in just a few months. It seems like the spring is getting weak quickly after installation. Anybody know of a "heavy duty" option to try?
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Joined: Jun 2006
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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?
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Fleet Mechanic
Joined: Aug 2012
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How about excessive pressure in the cooling system. Could this make the thermostat fail prematurely?
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Likely poor quality anymore.
I replaced my t-stat this time last year in the 06. I replaced several in my 87 Ranger.
I went thru several in several different engines in my old 74.
Yet, my 2004 Maxima with over 200,000 miles is rocking the original t-stat.
Josh
I replaced my t-stat this time last year in the 06. I replaced several in my 87 Ranger.
I went thru several in several different engines in my old 74.
Yet, my 2004 Maxima with over 200,000 miles is rocking the original t-stat.
Josh
Lead Driver
Joined: Oct 2010
Posts: 5,420
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From: Ouray, CO
It is because we have sg2/odb gauges. Never replaced a tstat in any prior ( all GM) vehicles in 30 YEARS. We are talking 5-10 degree drops and we replace the bad "tstat".
No idea how much other auto brands tstats vary though.
That's my 0.02.
No idea how much other auto brands tstats vary though.
That's my 0.02.
Lead Driver
Joined: Feb 2011
Posts: 8,241
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From: L.A. (Lower Alabama)
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*.
Fleet Mechanic
Joined: Jul 2013
Posts: 1,330
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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*.
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Joined: Dec 2003
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From: Stuttgart, Ar
It probably would get a little better MPG and even run a bit better with a hotter engine it makes sense anyway. Diesel engines work from compression and heat, basically you need a lot of both or you don't get 'fire in the hole' so I'll get me a new one swap it out and see what happens to my no load temps. I'm getting ready for winter here in Maine and the last thing I need is a cold engine when I'm using it. Does anyone know if I will be needing to but Tstat AND goose neck together or can I just replace the Tsta it self and use my old goose neck? and what is the advantage/disadvantage to one or the other? Thanks.