solved

 

Make sure your fan clutch is working. Do you have the radiator abroad on it? Mine ran hot when I didn't have it on. I replaced it and didn't have any more problems

 

Fan clutch is a new Aisin one and works fine. Factory shroud is in place.

 

might be a exhaust problem, if the cat is bad and causing pressure to build when u are on the gas more due to going up hill will cause more heat, how old is your cat and muffler? did u have this issue with the old motor that was in there?

 

Have your new radiator flow checked and or replace the t-stat.

 

What about swapping out tstat to a 190 or 180? Any downside?

Again radiator and Tstat are new and functioning as designed from what I can tell. The comment about the cat converter makes sense. Mine could be original. Any way to test it?

 

If you have replaced everything, that only leaves the guage sender. Have you tested the sender that sends the tempature signal to your gague? I have no idea what the specs are to test it and it may just be easier to get a new one. This is the one that is on the intake manifold, left of dead center on the head.

You quickly mentioned actual readings of tempature, do you have a mechanical tempature guage?

 

There are ways to test it but tis expensive. Time and mileage are usually the factors for replacement.
Poor driveability, low power, sulfur smell, glowing cat or exhaust manifold are typical indicators of a plugged cat.

Doubt it's your cooling system with the exception of the fan clutch. You should hear a "roar" when the engine is cold. Also you should feel resistance when attempting to turn the fan when cold.

210-215 is ok when pulling a grade in 5th gear. You're truck has an ECU ( I'm assuming it's fuel injected ) Fuel injected trucks run warmer than carbureted due to emission standards.

 

I do have a mechanical temp gauge so I know what is really happening. Both gauges go up together when it gets hot. Seems to be about 205-210 when the stock gauge starts climbing past normal.

According to LC Engineering they recommend a 190 tstat over a 195 stock oem rated one for better coolant flow. Sounds reasonable and I'd think they'd know their stuff. Does that make any sense?

 

i had a 87 pick up that one time i put a lower tstat in and took it out to the desert thinking that a lower one would help with cooling, it did just the opposite it ran over 195 the whole way and going up the hills it climbed over to 220. and all my other items where new too, so i ended up at the parts store getting a new 195 to put back in and it ran better on the way back. still getting warm at times, mine also had a problem if i sat at a light too long it would start getting warm and unless i got moving it wouldnt drop back down in temp. i never could find the issue and i replaced everything.

 

Check the timing and try burping the cooling system. There are a lot of threads on here about doing both correctly. Good luck.

 

Have already burped thoroughly. Timing was set with new motor install.

 

I would tend to say, as long as the tempature never get above 212*F, then you should be fine.

I would check the IACV, you may have some blockage in there and it is causing the entire system to plug up a bit.

 

have you tested the thermostat? Just because its new doesnt mean it works. Water pump maybe? Im kinda new here, but read a thread on only using toyota "red" coolant because the green causes oxidation in the block. plugged water jackets? good luck.

 

Are you using the original fan shrowd?

X2 on the cat. A buddy just replaced the cat on his Cherokee that was partially blocked. The results was a much cooler running engine as well as an overall improvement in performance.

 

Yours is giving the symptoms of a clogged radiator....I know you have a new 3 core but since it only seems to happen at 55mph range with the engine working hard to get up the hill then it looks like a water flow issue....usually the radiator water flow. Your new radiator does not have the external fins clogged with leaves or mud, correct?
Since air is not a problem at 55 mph we don't have to worry about shrouds or fan clutches. So, for some reason, water does not seem to be circulating fast enough....just for fun why not remove the t-stat and let it run wide open.....see if it has trouble on the hills then. I did that once on my old 84 Yota truck (no t-stat) and it took forever to warm up.

 

It it was me, I would also run a pressure test on the cooling system to see at what pressure the system is holding at.

One thing I did not hear you mention as being new - radiator cap??

Beyond that I have nothing left to contribute, its a simple system and it looks like everything has been answered. Don't know what to tell you...

 

What degree thermostat are you running now?

 

Oem 195 now.

 

I had the same problem with a little dodge back in the 90's, tryed lots of different things to no avail. the only thing that gave me some help, was to turn on the heater before I hit the inclanes, (driving on 100 degrees temp. with the damn heater full blast). I know it's not the solution, but may help you.