Ok I did my 195 to 180 thermostat today along with the coolant flush, GMB Water pump, and Gatorback belt.

180 thermostat - Napa #530080 (needs modifying)
Coolant - Prestone Dex cool
GMB water pump - #120-4350
Good Year Gatorback Belt - #4060875

Ok so ever since I have been a member people have always wondered which way the thermostat goes, and what the heck is the notch that people are talking about. And how you need to modify the much cheaper Napa thermostat that does not have a notch. Here are the pics!

First things first. My pictures are taken from the top of the engine looking down.

To remove the thermostat cover required a 8mm socket (2 bolts)

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Old 195 thermostat
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White o-ring thingy removed
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Old on left, new on the right
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Modified
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Why the notch is needed
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Direction of the flange in the o-ring
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O-ring installed on the new thermostat
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Inserting new thermostat
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Also 180 stat + water pump has moved my temp gauge down from half way to (see picture)

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now the questions: could this potentially keep the truck from going into closed loop mode for emissions/engine controls? Is it potentially bad for an engine designed to operate at a certain temperature not ever reach that temperature after installing a cooler thermostat?

 

From what I have heard the answer is NO. The 180 thermostat makes my engine temp sit around 192-195. The truck goes into closed loop at 180 (from what I have heard)

 

Thanks for the write up, Reid! This write up will definetly be useful.

I vote for it to be a sticky in the commonly asked topics ... now if only people would actually look there. Lol

 

Great write up man. I monitor my coolant temps all the time for tuning. With the 180 thermostat I stay right between 174 and 182.

 

Do you notice a change in the effectiveness of the Anti-Chicago Cold reverser? (heater)

 

I will know if there are any major changes tomorrow. I got done with 6 hours of working on my truck and drove home. I will be out and about and I will let you know if I notice any changes.

 

great write up. did you just use a dremel for the notch?

 

me in winter my fuel/milleage ration went down BAD!!! so it should not help at all? fuel economy?

what about a 160 degree? will the computer run fine?