Well..first off I have the 3.9L and have a CAI,Gibson cat-back,jet ST.2 chip with 265 Cooper SST so its a real dog....its not a huge power difference from cold to warm but seems to be more responsive before it warms up.....from reading on this forum....I would still like to add a set of headers,V8 TB and a few odds and ends.....now im really leaning towards the v8 swap to a 5.2...would love more to do a hemi swap....so should I change my t-stat or leave it?

 

to pitkanen44flyers---

from the V-8 tips and tricks page... The Magnum engines respond very well to a 180 degree thermostat. The factory thermostat is a 195 degree which is great for emissions but not so great for performance. Changing it out to a 180 degree model will keep the engine slightly cooler which will help make more power. Please be aware that just swapping the thermostat, without any other modifications, won't gain you a whole lot of extra power. All modifications work together and most will complement each other. Example: 180 T'Stat used with a Cold Air Kit, Headers, and a good Cat-Back system. The 180 degree thermostats will not affect your emissions output either.

i also backflushed my system when i put in the new thermostatwith a Prestone flush and fill kit, ($4.00) and followed the directions on the package...got some light brownish water and old coolant coming out for about 5 minutes and flushed til the water came out clear, added a gallon of new coolant, topped it off with water and i was good to go. i have usedthose Prestone kits in other cars and theywork as well as spending $70 to have the cooling system flushed at a shop and once installed you can easily do it again anytime you want in about 10 or 15 minutes, your only cost is coolant.

 

Funny...first, the 195*F thermostat is ideal for emissions. Then, the 180*F won't affect emissions. It can't be both ways...

The warmer thermostats are used for reasons other than emissions. One of the most important reasons to keep the engine that warm is oil life. Without a proper warm up, contamination in the oil won't get boiled-off, and oil life and engine wear suffers. Just as the article is correct in saying that all modifications work together, and complement each other, so too does the factory engineering. Change out one thing and there are cascading effects down the road (often times negative) that you don't realize. The engineers do know what they're doing.

I'm not saying not to change to the colder thermostat. But knowing the consequences, I wouldn't advise it (since NatesDakota did ask).

 

you forgot to highlight "but not so good for performance"... there is always a give and take with anything and the engineers dont see everything at the time they design vehicles. it takes people like us to tweak things a little to make things better. i think that somewhere along the line someone tried a 180* thermostat and it worked for them. they took the variant to the lower temperture edge and still make it work. thereare variants and tolorances in everythingand this happens to be one of them. 180 degrees is also at the lower end of the temperature range before the check engine light comes on, so if it is good enough for the computer, then it is good enough for me.if you try something different and it works, then its all for the better.

i dont feel 15 degrees is going to make a difference. many people on this site and elsewhere have tried it and it works, including techs, admin., and moderators in this site and i trust them. i can see in a colder climate it may not work as well but where i live my truck runs better with a 180 so i am leaving it in.

 

What is the diffiuclty level changing a t-stat out....on the 3.9l? Any walkthroughs or threads made?

 

scandall669, it's all good. I wouldn't advise you to go to the trouble to change it out either. Just so long as someone who hasn't done it before knows that there are pros AND cons to any modification.

On the 5.2L, the service manual recommends removing the alternator and A/C compressor and associated bracketry to get access to the thermostat housing. Indeed, when I look at it, you can't even SEE the thermostat housing, it's so far down in there. It looks like a good hour or two of work. Hopefully someone who's done it can confirm or deny what the service manual says about it.

 

i changed mine to a 180 a couple months ago and i didnt have to take out the alternator or A/C compressor or any brackets. it is about 5 inches under all that stuff, but there is access to the t-stat housing with a socket extention...it took me about 15 min. to change it. the hardest part for me was lining up the gasket in that cramped area but i could have solved that by using some silicone to "glue" the gasket down. so, in other words, the service manual is wrong.

here is a link on how to change it out...note the replys at the bottom of the page, one guy says he didnt have to remove any parts to reach the housing just like what i did.

http://www.dakota-truck.net/UPGRADES/TSTAT/index.html

as far as heating up to burn off contaminates, if one just runs to the corner store and back the engine will get hurt but i always let the motor heat to full temp even if i have a short trip.

im not a mechanic or an engineer, but i have had 318's and 340's in other cars and have worked on these for years. i know what they can do and what they cant do and these engines are not fragile as long as you take care of them.dodge, as with any other manufacturer says things to cover themselves and sometimes they go too far with it. its like tylonol saying not to take any more than 2 pills every 6 hours, but if you have a nasty headache i have taken more and it works. tylonol is covering their asses for legal reasons.things can be tweaked to add or help and as long as one uses common sense things will be fine.

 

This is correct. Colder stat would not allow the oil to get as warm as the factory stat. This causes the oil to be less viscous, which will decrease fuel economy AND performance. The change is probably small enough that it is unnoticable (fraction of a percent decrease in efficiency), but you would still traver further on a gallon with the warmer stat.

 

JRogers---

i am going by my experience...this has helped in my truck so i wont be putting the 195 back in. in a colder climate like i said in previous posts, i might not have done this, but the weather in NC is mild, even in the winter, so i dont have problems with warming up. my CEL isnt on, so it is obviously ok with the computer. 15 degrees is not going to make a difference in burnoff, if you put a pot of water on the stove, water evaporates at 180 degrees,plus i change my oil often enough to where i dont have to worry about contaminated oil...

 

I run a 180 degree thermostat in my4.7 Dakota. As for a colder climate- i also run an electric only fan that doesnt come on until the truck is fully warmed up; i get plenty of heat in the winter.

Asfor breaking down the oil: i totally disagree with other posters on this. I've runseveral trucks over the years stock (result is a blown head gasket and black oil - black oil is dirty oil) and i have run several more with 180 degree stats.Make a note of themileage when you change your oil and change the stat to a 180. I've always found the oilcontinues to look like honey (cleaner) far longer than stock. I've actually went to 10,000 mile oil changes - i've never lostcompressionon any motor-neverany problems.Not shorter oil life - much longer.