Thermostat
Posting Guru
Joined: May 2007
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The motor fires from heat combustion 203 is better than 180. IH motors run a 203, thats what they recommend, Ford engineers put 195 stat in our 7.3's that's what comes from the factory. leave the 203 in. JMOP.
Logistics Pro
Joined: Jun 2005
Posts: 4,243
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From: AZ
OK folks, just take one...there is plenty of popcorn for everyone!
I actually concur with jwhitetail...but this is always a fun topic...a lot like "What is the best oil?" thread. What is the reasoning for the claim of the 180 degree t-stat being the way to go?
Lead Driver
Joined: Jun 2003
Posts: 8,298
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From: Damon (South East Texas)
I actually ran the 203* t-stat for several yrs then went back to the 195* for a couple due to slightly elevated temps. Thermostats don't always last forever. I currently have a 203* t-stat and DS billet housing now. I saw a loss in mpgs with the 195* and regained it with the 203*. I am seeing EOT's that are in the normal range so I'm leaving well enough alone.
Lead Driver
Joined: Jun 2003
Posts: 8,298
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From: Damon (South East Texas)
Those are my thoughts too. All I know from real world experience that my truck "likes" the 203* better. 
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Elder User
Joined: Jan 2011
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From: Northern CO
The 180* Tstat was developed for the guys running the aftermarket oil systems. Since the aftermarket oil systems flow more oil than stock, the oil is being circulated more often and at higher pressures than stock. This brings the oil temperature up. With twin HPOPs it isn't unheard of to see EOTs in the 215-225* range. Personally with an ambient of 115*+, I have seen EOTs as high as 228*. If you put in a lower temp Tstat and lower the coolant temp, you're also helping to bring those EOTs down since the oil is cooled by the coolant.
Logistics Pro
Joined: Jun 2005
Posts: 4,243
Likes: 16
From: AZ
The 180* Tstat was developed for the guys running the aftermarket oil systems. Since the aftermarket oil systems flow more oil than stock, the oil is being circulated more often and at higher pressures than stock. This brings the oil temperature up. With twin HPOPs it isn't unheard of to see EOTs in the 215-225* range. Personally with an ambient of 115*+, I have seen EOTs as high as 228*. If you put in a lower temp Tstat and lower the coolant temp, you're also helping to bring those EOTs down since the oil is cooled by the coolant.
..My understanding of a coolant thermostat is that it simply regulates the temperature at which coolant begins to be passed from the engine to the cooling system components capable of shedding heat (radiator and heater core). So a 180 thermostat opens at 180 degrees, while a 203 opens at 203 degrees, etc. etc. The thermostat (in my thinking) has almost no control on the upper range of coolant temperature, only the start of flow to the radiator. I guess what I am saying is that two identical 7.3l diesels running down the interstate next to each other, one with a 180 thermostat and one with a 203 thermostat, would have the same coolant temperatures (after an hour or so). The only things that controls upper temperature of coolant are the size of radiator, size of water pump, size of fan and how fast this system can shed heat to the atmosphere. How does having a lower temperature thermostat "lower the coolant temp" and "bring down EOT's? I am not saying this to be argumentative, but to learn...I'm at my desk ready and all ears!
It's a Van Gogh
Joined: Feb 2010
Posts: 7,802
Likes: 1,331
From: Elk Grove, CA
I think the situation you describe would occur only if there was no thermostat. The thermostat starts opening at the rated temp, but only a bit. This allows some hot coolant out and cool coolant in. If the temps rise it opens a bit more, if the temps fall it closes a bit to constrict flow. This regulation of the flow of coolant balances at the rated temp.
Anybody else getting better mpgs with the 203*? I blew that off as codswallop... but mpgs are gooood!
Anybody else getting better mpgs with the 203*? I blew that off as codswallop... but mpgs are gooood!
Elder User
Joined: Jan 2011
Posts: 567
Likes: 1
From: Northern CO
What he said....
For some reason I always seem to confuse myself when I try to explain it. The biggest thing is a bunch of guys I know running the twin HPOPs have EOTs that are in the 200-215* range. With the 180* tstat versus the stock tstat, their EOTs are in the 190-205 range. I know it works. I just relocated my IPR dump for my pumps and that has made a difference around town, but haven't had a chance to see what it does on long drives. After I get that data, I will be putting the 180* tstat in.
For some reason I always seem to confuse myself when I try to explain it. The biggest thing is a bunch of guys I know running the twin HPOPs have EOTs that are in the 200-215* range. With the 180* tstat versus the stock tstat, their EOTs are in the 190-205 range. I know it works. I just relocated my IPR dump for my pumps and that has made a difference around town, but haven't had a chance to see what it does on long drives. After I get that data, I will be putting the 180* tstat in.
Lead Driver
Joined: Jun 2003
Posts: 8,298
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From: Damon (South East Texas)
With my Stealth Stage 1 HPOP (equivalent flow of 1.5 stock hpops) and the 203* stat, I generally see ~200* EOT on a 95-100* day. I have seen a max of 207* when running slow or ******* it with the a/c due to the added condenser heating. My temps with 203* are right inline with those running the 180* stat and dual pumps.
Post Fiend
Joined: Feb 2002
Posts: 10,600
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From: Carhenge
I think the situation you describe would occur only if there was no thermostat. The thermostat starts opening at the rated temp, but only a bit. This allows some hot coolant out and cool coolant in. If the temps rise it opens a bit more, if the temps fall it closes a bit to constrict flow. This regulation of the flow of coolant balances at the rated temp.
Thanks for the popcorn, Neal.