Before chasing a cracked block, I’d check that the water pump is actually still fine. Unfortunately new parts do come defective.

 

@Discoidiot

If you are still overheating that much my suspicion would be head gasket or cracked block. But start very simple :

1. Observe your coolant bottle is coolant circulating - see video below.
2. Check your fan and fan clutch - do you have the right fan is the fan clutch working at 220 it should be roaring
3. If the coolant is circulating - remove the thermostat does it overheat with no thermostat. Also confirm you have the thermostat in the right way -see Extinct's page to confirm
4. Add a coolant catch bottle

Coolant Flow

https://drive.google.com/file/d/1ZXJ...ew?usp=sharing


My grille area for refernence

Fan from driver's side

Overflow bottle, makes it easy to check for over pressure issues

 

Thanks for the responses, you guys are great:

I'm definitely seeing movement in the coolant reservoir, I assume that's circulating?

Fan is spinning like crazy, yes.

Have not removed the thermostat but I have replaced it and verified both the new and old open just before boiling (pot of water on kitchen stove) and I've installed the thermostat with the spring facing towards the interior of the car, the "dome" facing towards the front of the car.

How can I check water pump short of pulling it? I've pulled the serpentine belt and spun the water pump by hand and it flows nicely and no bearing sound

Thanks all

 

@Discoidiot If the coolant is moving in the back of the coolant tank as per my video, your water pump is working or there would no movement. I would try with no thermostat, it does two things it will force any air out of the system, and if you are still running too hot proves an engine issue as most likely.

Pull the thermostat, raise the coolant tank as high as possible and remove cap. Start the engine and monitor the tank level,top as required. If you have an engine issue the temps should continue to rise even in this state.

 

Agreed, remove the thermostat completely. You can put a pressure gauge on the cooling system with a simple tee if you want, or maybe just loosen the cap one full turn from full tight. Slip a hose over the overflow tube and run it up to the cowl area so it does not spit out on the ground. When did this issue start? Overheat event?

 

OK - quick update. Prior to new radiator, without the thermostat it would climb and climb. New radiator, with thermostat = climb and climb. New radiator, no thermostat = temps around 168-173 on a 60 degree day outside.

I thought I read without thermostat I should be running 150-155. In Santa Fe at 7500ft, is that increase due to that?

OK to run without thermostat? Can't send video, file size too large

 

@Discoidiot No thermostat,you hit the average running temp. My Disco runs that with a 180 high flow, an only climbs under higher RPM and hills as expected. Generally speaking @Extinct can confirm our engines can hold about 100 over ambient more or less.

I would run no thermostat for a few days, you may get a low temp code. Try a long up hill drive if you have a hill locally and see what happens

Then add the thermostat back you may of had a big air bubble, trapped somewhere that can really mess with your engine temps.

 

For those few interested - took the truck for an errands run around town for a few hours today with the thermostat removed. Outside temperature was 69-72 degrees here in Santa Fe. Mostly stayed around 180 degrees, but for a bit in stop-and-go traffic it got up to 195 but once on the highway with good speed it was down around 182. I opted to turn on the AC full and we were around 190 for 30 minutes. Never above 200 and overall maybe 2 hrs of driving.

Thoughts? I'll drive some more tomorrow before re-installing original Extinct thermostat and see what she does...

 

Yes, seems to be normal without thermostat, I would also drive a few more days without. Hopefully it is just a bad thermostat element (lifetime warranty if it was one of mine). I did have a local customer with similar issues we chased for three + years. It all started with an overheat event (ran over a ladder on the highway, busted the lower hose) that got progressively worse and worse. At then end, running no thermostat at all it would overheat super quick. Turned out to be cracked block. But hopefully you do not have that. How did this all start?

 

@Extinct it was one of your elements, but it looks to work fine in a pot of water on the stove, along with another one I bought from local parts store, thus baffling me.

As far as an event, early April was the trip up to Denver and back, over Raton pass on the way back we hit 238 and quickly 242, but no more than 10 seconds and I blasted the heat before coasting down the mountain and temps dropped back to 215. After that, I swapped over to the Extinct Inline from the new factory I installed in January. Temps after that never got above 205. Then last Sunday I drove down to Albuquerque and noticed my temps were high again, back to 240, and again, blasted the heat and dropped back to 215. After that is when I decided to test/swap the thermostat element and started this chase. On the test drive with the new thermostat I hit 250 for a brief second and the red light came on (I was already on the way back home from the 1 mile away test drive) It definitely got hot quickly, so that's when I decided it must be a plugged radiator and ordered a new one.

I'll keep running like this for a few days and see what comes of it. The girlfriend wants the truck back, but I'm nervous because I never know if she watches the temps...