203 T-Stat ?
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Senior User
Joined: Jul 2006
Posts: 226
Likes: 0
From: Jeffersonville , Indiana
203 T-Stat ?
Was thinking about trying the Dieselsite 203 t-stat. Was wanting to get some input from some who are using one or have used one in the past. Did you see any mpg increases? Thanks for any input.
Not a liberal...
Joined: Jul 2006
Posts: 6,635
Likes: 4
From: Cut & Shoot, Texas
I've been running one since '06. No real change in performance except for really hot heater air. What I would reccomend from DieselSite is the billet thermostat housing. The stock ones on these motors is junk and they will leak eventually.
Lead Driver
Joined: Feb 2000
Posts: 5,374
Likes: 46
From: Palm Bay, Florida
I've had one in mine for 5 years, I personally choose to believe in what Bob @ Dieselsite says about these, Navistar International made the engine, THEY have been making Medium and HD trucks and Diesel engines for a VERY long time, THEY should know what heat range THEIR engines operate best in!
http://www.dieselsite.com/dieselsite203thermostat.aspx
http://www.dieselsite.com/dieselsite203thermostat.aspx
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Cargo Master
Joined: Jan 2009
Posts: 2,800
Likes: 31
From: OKC, OK
make sure when you install the housing you use the gasket AND rtv around the outside. Mine leaks and I have heard of a bunch if other people having to go.back and add rtv because it leaks
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Brett Foote
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Joined: Sep 2003
Posts: 12,253
Likes: 763
From: Houston, Texas
I've had one for a few years now and have actually done a study on the 203* vs 195* vs Terminator's 180*.
Stock, the 203 doesn't make that much a difference and as many have said before, you end up with a warmer heater.
Tuned, whether you're running a hand held programmer or a custom chip, it helps burn the additional fuel the injectors are dumping, better. It works even better if you're running aftermarket injectors.
I ran the stock and 180* thermostat and found that the truck ran good, but tried the 203* just to see what would happen. With my truck equipped the way it is now, the 203* helped allow for a more complete burn with the amount of fuel my Stage I injectors are dumping. I also noticed that the truck ran noticably better and quieter once it warmed up as opposed to the stock or 180. As far as mileage, I average anywhere from 16-19 mpg where as the stock and 180 got me around 14 to maybe 16 if I was lucky.
If your truck is bone stock or slightly modded and not tuned, stay with the stock 192 or 195.
The 180 works well if your truck spends most of it's time towing heavy.
If your truck is well modded or tuned, the 203 will serve you better.
Stock, the 203 doesn't make that much a difference and as many have said before, you end up with a warmer heater.
Tuned, whether you're running a hand held programmer or a custom chip, it helps burn the additional fuel the injectors are dumping, better. It works even better if you're running aftermarket injectors.
I ran the stock and 180* thermostat and found that the truck ran good, but tried the 203* just to see what would happen. With my truck equipped the way it is now, the 203* helped allow for a more complete burn with the amount of fuel my Stage I injectors are dumping. I also noticed that the truck ran noticably better and quieter once it warmed up as opposed to the stock or 180. As far as mileage, I average anywhere from 16-19 mpg where as the stock and 180 got me around 14 to maybe 16 if I was lucky.
If your truck is bone stock or slightly modded and not tuned, stay with the stock 192 or 195.
The 180 works well if your truck spends most of it's time towing heavy.
If your truck is well modded or tuned, the 203 will serve you better.
Veteran/Sheepdog
Joined: Feb 2012
Posts: 6,047
Likes: 110
From: Western AR
I bought the housing and thermo from them as well. The housing leaked after 5k miles, and I was able to find a Dorman donut gasket that was a little thicker. No leaks after I put that in. I did not notice an improvement in mileage...stayed the same. Now I am back to a 192* thermo and a T444e water pump with spin on filter. Will see soon if there is a noticeable change with the 192* back in there.
You can see the billet housing in he photo.
You can see the billet housing in he photo.
Elder User
Joined: Sep 2011
Posts: 659
Likes: 1
From: Millstone, NJ
Thanks for the heads up.
Elder User
Joined: Sep 2011
Posts: 659
Likes: 1
From: Millstone, NJ
I've had one for a few years now and have actually done a study on the 203* vs 195* vs Terminator's 180*.
Stock, the 203 doesn't make that much a difference and as many have said before, you end up with a warmer heater.
Tuned, whether you're running a hand held programmer or a custom chip, it helps burn the additional fuel the injectors are dumping, better. It works even better if you're running aftermarket injectors.
I ran the stock and 180* thermostat and found that the truck ran good, but tried the 203* just to see what would happen. With my truck equipped the way it is now, the 203* helped allow for a more complete burn with the amount of fuel my Stage I injectors are dumping. I also noticed that the truck ran noticably better and quieter once it warmed up as opposed to the stock or 180. As far as mileage, I average anywhere from 16-19 mpg where as the stock and 180 got me around 14 to maybe 16 if I was lucky.
If your truck is bone stock or slightly modded and not tuned, stay with the stock 192 or 195.
The 180 works well if your truck spends most of it's time towing heavy.
If your truck is well modded or tuned, the 203 will serve you better.
Stock, the 203 doesn't make that much a difference and as many have said before, you end up with a warmer heater.
Tuned, whether you're running a hand held programmer or a custom chip, it helps burn the additional fuel the injectors are dumping, better. It works even better if you're running aftermarket injectors.
I ran the stock and 180* thermostat and found that the truck ran good, but tried the 203* just to see what would happen. With my truck equipped the way it is now, the 203* helped allow for a more complete burn with the amount of fuel my Stage I injectors are dumping. I also noticed that the truck ran noticably better and quieter once it warmed up as opposed to the stock or 180. As far as mileage, I average anywhere from 16-19 mpg where as the stock and 180 got me around 14 to maybe 16 if I was lucky.
If your truck is bone stock or slightly modded and not tuned, stay with the stock 192 or 195.
The 180 works well if your truck spends most of it's time towing heavy.
If your truck is well modded or tuned, the 203 will serve you better.
Will the 203* aid the engine in warming up faster from cold starts?
Posting Guru
Joined: Sep 2006
Posts: 1,081
Likes: 1
From: Montana
I put in the 203 when I owned my truck cause I burned VO. worked fine.
now I have a van and might not go that route cause its already a warm running motor cause of all the body that sites around it.
would be curiuos though
now I have a van and might not go that route cause its already a warm running motor cause of all the body that sites around it.
would be curiuos though
Cargo Master
Joined: Jan 2009
Posts: 2,800
Likes: 31
From: OKC, OK
Correct the gasket goes inside the housing...then put rtv on the metal surfaces outside the gasket/o ring. You will see when you install it.
Veteran/Sheepdog
Joined: Feb 2012
Posts: 6,047
Likes: 110
From: Western AR
Yes the gasket that came with the 203* was a tad thinner than the Dorman gasket I bought at local autoparts store. The difference was significant enough (maybe 1mm?) to cause it to not seal well. The RTV would have probably been all I needed to do, but the Dorman was $2.