After 5 years of having my truck and especially that winter has now toned down a lot...I found out that the thermostat I had sucked. All this time I've dealt with long waits after start-up for my engine to warm up and crappy gas mileage. I've probably had 14 MPG at best in the summer time. My engine temps have NEVER exceeded 185 degrees F...even on the highway. Not to mention the long times I had to wait for the heat to come up.

Anyway...I replaced my thermostat with the stock 195. Turns out I either had a 180 in there or the thermostat was stuck open, which would explain long warm up periods. Took her out for a good 50 mile drive tonight. My warm up period has improved by half the time it did before. Usually I could never actually see the needle move before my eyes, but this time I saw it move up rather quickly. It does indeed sit at 195 during city driving. I've actually reached 210 - 220 degrees driving on the highway.

I can't wait to see how this has effected the fuel economy if the problem did exist because of the engine temps. I do know for sure my heater heats up faster...which is great...but winter is pretty much over =P

 

haha nice. glad my thread got ya thinking about that.

 

Heh, yea I've been contemplating about it for a while now. Lately I've been seeing posts about thermostats a lot, and it kept pushing my mind about it. The thought was, "will 15 degrees really make that much of a difference?" A new thermostat is like 20 bucks, plus I have coolant in the garage, so I thought...what the hell, it'll probably be worth it. It's kind of funny...cuz I was thinking to myself "Hmm...my **** takes forever to warm up...I've never seen the needle exceed 185...and I get 10 - 14 MPG all year. There has to be something screwed up."

Even if I got a 180 as a replacement, I think it will still have been an improvement, because the evidence is showing that the stat was probably stuck open. I wouldn't know for sure until I've driven another similar truck.

 

Yeah i've been thinking the same too my truck during the winter is low maybe 150-160max even summer time 80-90 degree weather with the a/c on idling I wont see past 190. That would be nice to find out that I dont have a 195 stat and hopefully give me some better mpg

 

What brand thermostat did you guys get?

 

For all I know mine could have been the factory stat. The 4.7's just have a rubber seal around them, and the gasket was white, and I don't think I've seen new ones with that kind of seal. That's aside the fact of the other pieces of evidence. If you have a hayne's manual at hand, and willing to spend 20 bucks on a new stat. If you get at least a little MPG improvement, it'll still be worth it. I lost approximately a gallon and a half of coolant, so buying new coolant is another factor.

I was in Autozone when I was getting oil and such, and they had the Duralast one. Other than NAPA brand, I don't know if I've seen another kind of brand.

 

my gasket was white also with the stock 195.

 

jet perfomace makes a stainless one last i checked was 45 bucks but the seal sounds like one for a cummins it has a seal that goes around it

 

How do you know if its 180 or 195? Mine takes forever to warm up it seems and the needle never gets even to halfway. I have no clue what scale the stock gauge is at so it's hard to tell how hot it is really.

 

On the left between 130 and 210, half of that would be 170. On mine it was just a tad past the halfway point...so it was around 180 give or take 5 degrees. On my longest drives it has never exceeded that point. It means it's either stuck open or it's 180. On my newly replaced one I've actually touched 210...I was going 80mph, though. =P So I now know something wasn't right before.