Thermostat need to be replaced?

[BigClay]

I was driving my truck this weekend (96 Dodge V10) and I noticed that the temp guage was sitting around 180, even though it was hot outside, and I was driving in the city. This got me thinking that the last time I drove the truck in the winter the heat was never really hot. So two questions. First does it seem the t-stat is bad and has defaulted to open. Next, with it so hot outside, is this really a problem (i.e. how bad is it for the engine to run cool)?

 

[shawn]

Well... what thermostat is in it? Are you sure the gauge is correct? If it has a 180F or 195F thermostat, it should sit there at rated temp all day long, and only come up a bit if you're working the engine really hard.

The big question is whether or not it gets up to temp in the winter. If it doesn't hit operating temp within about 10 minutes of driving time in the winter, the thermostat is probably leaking or stuck open. But I'd expect to see some indication of that in the summer, too. Maybe cooling off too much when the truck is idling, etc.

 

[transman731]

from the factory it should have a 195* t-stat.(required temp to run closed loop)
if it's only running 180* i would say it's either stuck open or the fan clutch is stuck on.

 

[Tim C]

from the factory it should have a 195* t-stat.(required temp to run closed loop)
if it's only running 180* i would say it's either stuck open or the fan clutch is stuck on.

X2. Id bet its a bad thermostat. If that big fans clutch was stuck on it'd sound like a prop plane on takeoff, lol.

 

[BigClay]

So planning on replacing the thermostat tomorrow. Would putting in a 180 degree one be beneficial?

 

[transman731]

if it's a dd, you need to try to keep a 195* in it.(unless it calls for something different)
running a 180 in it will cause it to use more fuel. the pcm is always thinking it's cold.

 

[BigClay]

It is a dedicated tow rig, would that make a difference?

 

[transman731]

does it run hot when your towing (higher than normal) ? i would run a stock t-stat and see how it reacts.

 

[BigClay]

It never got real hot, but the temps would rise.


I ended up changing the thermostat, there was a 180 in there and I put another 180 back in. So doing some highway driving for about 30 minutes today, I took a picture of the temp gauge, see below (crappy cell phone pic). 130 is the low number and 200 is in the middle. The needle is right over the 2 in 200. Do you think it is still running cool, or is that about right or a 180 thermostat?

 

[Caver Dave]

Do you think it is still running cool, or is that about right or a 180 thermostat?

That'll be determined by what your ECM *THINKS* the temp is... I'd think the 195* would've been a better route, but...

If you need to hit the block/rad/hoses/sensors with a couple different IR guns to see where it *really* is temp wise, LMK! I've got 2 that are usually within a degree of each other