We just reinstalled my factory temp thermastat back into the Rover and properly bled the system just to see what type of temps I would get and to check the rad for any blockages. I had temps of no more than 212* idling and aux fan coming on at 210*. I have no plate on the truck right now so can't check driving temps yet but will be getting a temp plate tomorrow.
As for the rad, I don't have a infared sensor so I did the hand test. Standing in front looking at the windshield and driverside being right side, the rad was really hot top right (inlet) and hot across the top and half way down. The bottom right was cold right across to the left. The difference between the hot and cold was quite sharp and not gradual as I would think it should be. I believe this could point to a plugged rad, any thoughts?

 

Rad is horizontal tubes, all fed in parallel from the plastic side tank. Sludge or calcium build up or Dexcool mud will keep flow low in bottom rows, and they will be a lot cooler (more than 10F).

 

The difference is way more then 10* , the difference is more like grabbing a pot of boiling water versus a frozen juice container as the lower part of the rad is litterly ice cold. I would suspect the lower part of the rad is getting no flow at all.

 

The rad on my dad's truck felt exactly like that when the t-stat wasn't opening properly. I was seeing temps 207-212+ at idle, because the heatercore was doing all the work. Up to speed temps were fine because I think the pressure forced the t-stat open anyway. Your rad could very well be restricted, but it sounds maybe like a t-stat issue to me.

Or maybe you still have a bit of air in the system, it can be hard to work it all out, even following the proper bleed procedure.

 

The D2 has 2 possible radiator/hose configurations. The radiator required for secondary air injection (SAI) is different than the one without. They are in no way interchangeable. I was shipped the wrong radiator and had to eat it.

 

Up here in Canada I don't we ever go the trucks with SAI but we will be careful when ordering our new rad.

 

I came across to your posts here... exactly what I am going through now...
New t-stat, new radiator... no head gasket issue, good water pump ( i removed and checked...) no single reason for overheating...(no air in the cooling) no overheating when idling... no overheating when on the highway, but stop and go will over heat...but never reaches to the red section. Since there is no high pressure pump there...the high pressure is caused by the heat... and also I tried a different fan clutch... same problem again!

A lot of pressure in the upper hoses when overheating starts... top hoses are hot as hell, and the bottom **** from radiator to t-stat, as well as the bottom of radiator is cold...

I did not check if my radiator is the kind for secondary air or not... this is the only think...

I am very good in repairs... and this is mysterious... I have been working on this for over 6 months with no avail!

Your posts ends without conclusion, so I assumed you may give me some insights? Best,
K