I decided to take the truck (see sig) to town yesterday for my semi-weekly shopping trip. It's about a 90 mile round trip. This is the first time I've really driven it that far since the temps have started to go down. The outside temp was between 35-45 for the whole trip.

I have an Edge Evolution installed and one of the PID's I monitor is the Engine Coolant Temperature. I noticed that it warmed up to around 186 but that is about as high as it would go, driving 60 MPH on the flat's. It would go down as far as 182. When I hit the hills, it went up to 192, where it usually runs, but as soon as I leveled out it would drop back down into the 182-186 range. When I hit the outskirts of town and started slowing down it dropped down as far as 176.

On the way home, it made it up to 176 for the first part of the trip, down the hills and onto the flats. By the time I made it home it made it up to about 186. The only time during the trip that it went up to normal (192 where it normally runs), was when I was going up the hills.

This time last year I noticed that it took a long time (20+ miles) to warm up. Thinking it was just because it was a diesel, I bought a grill blanket from Cabela's and it seemed to be fine, but I'm beginning to wonder if I have a thermostat that is not closing all the way.

Also, I've noticed pretty much as long as I've owned the truck (I bought it August 2007) that whenever I point it down a hill the temperature drops off, going as far as into the 170's on a long downhill run.

So if anyone has any idea's, if this is normal or if it isn't, I'd appreciate the input. I can understand it not wanting to warm up, or stay warmed up, when it is really cold. But it seems to me that 35-45 outside isn't that cold.

As well, any tips on the changing the thermostat would be appreciated. They aren't expensive, but the shop manual I have has me draining all the coolant, taking off the CAC hoses and a bunch of other crap. If I need to change it I'd like it to be as easy as possible.

Thanks,

 

Sounds like fairly normal happenings for a diesel engine cooling system to me.

 

That's good to hear. I really don't want to mess with the thing if I don't have to.

I have a followup question also about the winter grill blanket. Last year when I put it on it seemed like I lost a couple miles per gallon. The thing is, I don't know if it was just that my putting the blanket on coincided with the switch to winter diesel, or if the blanket somehow caused me to lose mileage.

The only things I can imagine are the blanket restricting air through the CAC, or the blanket causing the intake to suck much warmer air from inside the engine bay, instead of pulling it in from outside like it should.

Does any of that make sense? This is my first diesel, so I'm still learning the ropes.

 

Bumping this up, to see if anyone else as any input.

Thanks,

 

I would say it is probably the winter fuel, my mileage always drops a mile or two per gallon...