Slightly overheating after prolonged idling

I'd put in a new fan clutch. Sub 100 dollar part, easy to do, see if it makes a difference. Mine died at 80k~ miles.

 

https://static.nhtsa.gov/odi/tsbs/2019/MC-10166026-9999.pdf

First time I've heard of that. Should have been factory imo.

 

Sad thing is, it is factory for some other markets. If you read that TSB, you'd NEVER want it done. It's hack job on the wiring harness. Can't believe a room full of engineers could come up with a better fix.

 

I would be concerned. My truck doesn't get that hot. Middle of the gauge is around 190-200. You are getting 220 and up based on the needle. 210 is as high as I've ever seen on my OBD2 gauge and it correlated to slight right of center on the dash.

I think something is wrong with your cooling system.

 

Do you mean you don't notice a cold engine at startup reads all the way to C and as you drive it the needle moves to the middle?

 

Should have clarified. I've seen it go from C to the middle of the gauge, but I haven't seen a temp needle do anything else. Based on my OBD scanner I expect it to move all the time. In the winters the engine runs about 185-195 and in the summer when towing I've seen it run up to 210. 185 to 210 is 25 degrees and probably represents 10% of the full sweep of the gauge assuming (probably incorrectly) that the gauge is linear. Even 10 degrees is probably twice the width of the needle. For car guys, we would definitely notice that needle moving constantly even as the fan clutch cycles on and off at a stop light.

I have motorhome on a Ford chassis and I know those gauges are idiot lights. Folks on the Ford forum say they are three position needles moving through heavily damped motion to represent cold, normal and overheating. In the desert I can go from 225 climbing a hill to 180 coasting down the other side in less than 30 seconds and the needle never moves. I wish it did and then I wouldn't need a OBD scanner.

 

I added that fan to my truck and while it does help with the AC, it’s weak enough that it isn’t going to do anything to help engine cooling.

 

It’s really not, it’s inserting or splicing two wires into two connectors behind the dash and then running the harness through the firewall and installing the fan and plugging it in. There is really nothing hack job about it. It looks a lot scarier than it is.

 

For the sake of the initial post, I would be concerned if my gauge went anywhere beyond half. I have never seen mine do that even in 110°F heat with AC at full blast while idling. That to me means that going beyond half is not normal and something should be done to fix it if possible.

I would change the fan clutch and read the actual temp via OBD to see what it is. Also verify no mud or anything else clogging the radiator. And if you can’t solve it to get it back to normal, you might consider upping your oil viscosity to a 30 or 40 grade so the oil doesn’t thin out too much in those conditions. Oil pressure is already not very much at idle, if you thin that oil out with an extra 20° of heat, that could be bad, especially if happening often. I don’t know how high above normal temp you are currently, but the needle doesn’t budge for much. I bet you’re in the 230s at that point, which really starts bringing the oil down in thickness from where it should be.

 

Im shocked that there are so many people claiming that it's the fan clutch. These are stupid easy to diagnose. Cool engine results in free spinning fan
Get the engine up to temp and the fan should be harder to spin. Verify no off axis movement and the fan clutch is fine.

This could be a low coolant issue, clogged radiator fins, system not keeping pressure, even older coolant doesn't cool as efficiently if he's running the same coolant for 130k miles

 

Is the front of the radiator dirty with leaves and bugs?

You can try spraying water on the radiator with a hose and see if temp comes down. If that helps then sometimes it means there isn't enough heat exchange going on through the surface of the fins. I do that more when troubleshooting a/c problems but the theory is the same

 

Crossing the border?.... make damn sure your PAPERS ARE IN ORDER ..!!!...

 

Cause OP is not the 1st with these symptoms.

 

Earlier revs of the TSB was a hack job. (They were literally taking a fan from a different vehicle and hacking off the mounting ears.) Current TSB is a clean installation with application-specific fan and repinned connectors.

You can also just buy the fan and dumb-wire it to an independent switch on the dash. Just turn it on manually for extended idling.