I am looking for some guidance on overheating situation.
Here are the facts:

2003 Discovery 2 ~125 k miles
Truck overheated a few weeks back
Pulled the heads off and pressure tested the block-OK
Machined the heads and replaced head gaskets, oil pan gasket, oil pump and timing chain
8 mm Kingsborne wires, new low $ thermostat from Lucky 8, Ultraguage
Throttle body heater delete
Purged the coolant system, truck fired right up but temperatures are high
I have since pressure tested the coolant system (held 15 psi for hours with plugs out)
With pressure tester connected to expansion tank I observed the following:
7 psi at 100 F
10 psi at 180 F
15 psi at 208 F
Electric fan kicked on at 210 F
18 psi at 221 F
20 psi at 230 F -shut it down

I am still using Dex Cool
My next step was to put in a new radiator and switch to regular green antifreeze.
Is there any other troubleshooting I should do?
Thanks

 

Definitely replace with green coolant. The thermostat could very well be your problem. The cheaper thermostats do not like to work sometimes. I'd drop it in some water on the stove and make sure it's opening.

You can see if the radiator is blocked with an IR temperature gun. $12-15 online, $20 at Walmart. Let her get up to 170-200 and see if the radiator is consistent temps top to bottom. Side to side the temp should change as a gradient. Up and down should be pretty consistent.

 

Are your facts at idle and standing still? What are your temps when driving the vehicle at 25-45mph?
......

 

I have a friend with a thermal camera, I will borrow it and get an image. In regards to the thermostat the upper hose has pressure when it warms up so I assume its opening.

 

These temperatures are at idle.
I'm nervous to drive the vehicle for fear of overheating.
While revving the engine at 2000 rpm the temperature still creeps up.

 

Or do like the pro's do here, and park it on one of these

I'd make sure you don't have an air pocket in the cooling system. I personally fill it, run to 195F shut off until it cools, fill thru the bleeder, and top off reservoir, then run up to 195F again, and top off one more time thru the bleeder, and top off the tank.

You might want to test the flow thru the radiator as well. Replacement radiators can be purchased online for as little as 55.00 to 300.00 just depends on what you want to spend.

 

The factory system is a bypass system, so hot coolant will still circulate and build pressure.

 

Why did it OH a few weeks back?

New thermostat a good idea. Did you inspect the old one for debris?

Bled properly?

If you take a short ride and keep an eye on the temps you're not likely to crater it. It would also help to get more coolant flowing through the system to eliminate possible air pockets that might prevent a good flow.

If it doesn't OH when driving at a moderate speed you should be able rule out a radiator and look at a fan clutch. Electric fan should lower the temps & keep it from OH but there's no guarantee of that since the temps are already up there and the fan is old.
......

 

I do not know why it originally overheated.
I was a knucklehead and tore the engine apart convinced it was a head gasket.
The coolant system is definitely bled, I've checked a few times.
I did not know the top hose would have pressure even if the T-stat was closed.
I'll check the thermostat and get a look at the radiator with the thermal camera.

 

Park it on a hill. Its the only way you can insure the heater hoses are pointed in the upward position.

Do you have heat? When it gets hot, do you turn on the heat to see if it drops the temp?