My exhaust system is new from the manifolds back. New O2 sensors as well. No codes either.

As I said, prior to the mod, my highway temps were around 185-190. I'm not sure why the mod would give me lower surface road temps, but higher highway temps.

I guess as long as it stays below 210 F I should be fine.

 

That's not normal, I am thinking you have an issue. I would recommend we start by removing the thermostat element completely and see what it does on the highway. One of the forum members was having similar issues last September, his radiator was replaced the previous January and he was having problems with it running 217-221 on the hightway. He replaced the radiator and it went back down to 100 over ambient (south Florida, so 95 was ambient). I will ask him to chime in here with his experience.

You are not far from me, If we get to that point I have two pullouts that were in good shape I could let you use to test before you use order another one.

 

Got a pic on the drive home from NC last night. Orange circle is intake air temp,red is the engine temp. You will have to zoom in but the engine temp is 177.



225k on the factory engine, winch bumper with winch, factory spec 16" tires

 

Hi TimInNova / Extinct

Yes I had the same issue when I installed the inline thermostat. My always high temps reduced in town driving but on freeway they would spike and stay there. Frustrating because everything in the cooling system had been replaced. Troubleshooting with Extinct we determined it must be a flow issue even though the radiator was less than six months old and was purchased from Atlantic British. So it wasn’t a generic radiator from a no name company. I purchased replacement from lucky8 and did the replacement myself (this time) and noticed the AB radiator was really banged up for being new! Not sure if this applies to what is going on with yours. One thing that was really handy, Extinct may have already mention but a handheld temp gun was very useful to troubleshoot and see what temps you have at each side of radiator and throughout the cooling system.

 

Had someone ask, obviously the AC was blowing wide freaking open - wife was in the truck and she likes to be cool.

 

@tim
My radiator is a new Nissen, but that's no guarantee that something didn't get lodged into it.

Outside temp today is suppose to be 94 F around 3pm. I'll take it out again onto the highway and bring my hand-held IR temp gun and take some pre/post temps on the radiator.

I think what adds to some of the confusion on this thread is that folks don't always state where they are getting their temperatures from; the engine sensor (via OBD2 port) or a remote sensor. My remote sensor for my physical gauge is right before the intake of the radiator, and is always 8-10 degrees higher than that of the OBD2 port reading. I suspect that is due to extra heating time between the intake manifold and the radiator.

 

If you have time go ahead and pull the thermostat element out of the housing and run it with no thermostat element installed

 

I will try this tomorrow, as it will need the rest of the day to cool down. I just got back from a quick drive on the highway. Outside temperature is 90 degrees.

The OBD2 speed is actually 6pmh less than actual speed due to my larger than stock tires. So 59 mph is really 65 mph

At 65 MPH my OBD2 temp almost hit 200 F. Once off the highway, temps never went lower than 195 F.

Due to the housing being effectively "glued" shut with sealant, it make take more than a day to remove the 180 thermostat and reseal the housing for a new run.

 

I wouldn't worry about resealing super tight without the element as you know you are not going to run it that way long term. Just slap some silicone on it and go, if it drips a little so what, it is just for testing purposes.

200 degrees running at 95 ambient isn't completely out of the ballpark, but I don't want to see 110-120 over ambient. I am highly suspect of your autometer also, usually it gets colder farther away from the engine. As stated above an IR gauge can be used to doublecheck..

 

@Extinct For clarity when you say 100 deg F over ambient is that thermostat dependent ie 180 or 170 or in general ? Mine goes in this afternoon, seems like a nice job to do in 90 deg heat in the sun