Truck: 2006 6.0, 130,000 miles, bulletproofed, studs, EGR delete, SCT tuner, blue spring mod, coolant filter, new oil cooler, also has new injectors and turbo.

The coolant was recently flushed, but was replaced with ford coolant gold (I know, and it will be changed in the future) within the last 5k miles, when I bought the truck.

Now that temps have started dropping, I've noticed something.

The water temp gauge does not always read where it should be. And after keeping an eye on it, I've noticed a pattern. How high it reads is relative to the outside temps.

OK, at this point, you're thinking I'm crazy. I promise you, that is not the case.

when the outside temps are around 80F+, the temp gauge loks and reads normal. When the outside temps are like this morning, between 30F-40F, the gauge never moves, even after an hour of driving. Truck runs fine (it does hate the initial start-up when cold, but smooths out after I let her idle a few minutes)

Anywhere between the 40F and 80F, the gauge moves to a spot relative to the outside temp, so at 60F or abouts, it is around halfway up, at 50F, around 1/4 the way up, and so forth.

I really was not too concerned with it, as it has been running fine, I've checked the coolant, level was fine. It is now time to change the coolant filter again, will be doing that tonight, going to the dealership to get a gallon of coolant to top the coolant off with. However, this morning, after I got in the truck after letting it defrost, and turned the panel heat on, I noticed that it was not really blowing hot, it was blowing, and it was maybe warm, but not the level of heat that I've come to expect out of this truck, granted this morning was the coldest it has been outside when I've been driving it.

Any suggestions, places to start looking at? Immediate concerns, etc?

Only notice any kind of smoke on start ups in cold weather with a cold start <50F. I have maybe noticed a slight decrease in mileage the past month, I've been attributing that to longer idle times since the weather is colder, and I don't like cold leather seats so I give it mroe time to heat up. I never, or almost never put her in gear within 5 minutes of a cold start, even when weather is warmer.

Thank you,
JD

 

Start with a Tstat, and work back from there. Does your tuner give you OBD numbers from the trucks computer? The temp guage is more of an approximation, or idiot light, than an accurate guage. I use dashboss, do you have a way to read live data? I suppose the guage is capoot, but seems to me that your Tstat is stuck open, at least partially.

 

I'm an idiot. You're right. Tstat has to be stuck open. Makes sense for both symptoms.

 

YOU NEED an ODB2 gauge reader.
The dash gages are not very useful.

Lots of threads on scangauge2, torq app, etc. which will let you read TONS of VITAL information about your engine. It'll show you EXACTLY what your temps are - vs. high/middle/low of the dash gauge.

 

I know. I'm planning on it soon, along with egt gauge and some others. Having to spend funds elsewhere ATM though, like the trashed body mounts, and a bent steering stabilizer, weak driver side coil spring, carrier bearing (probably go with 1 piece shaft), and I have slack in the driveline somewhere, and a vacuum leak to the auto hubs (I think...manual works fine though for now)

The sct I think has some limited obdii reading doesn't it, or at least just read codes? That doesn't work right now due to a blown fuse from running an air pump off the 12vdc plug.