"approaching the red..." are you serious right now? just stop giving advice. Don't even comment with ignorant suggestions like this. Some poor guy is going to take heed to this and cause catastrophic damage to his engine.
Here everybody. this quote is taken from another website forum today. The dash gauge does not work the way that you think it does. Stop referencing it. Don't tell others to refer to it. Get an aftermarket sender and gauge or a digital unit that will tap into the ECU via OBD plug.
chasen7:
"All in-town driving, 71 degrees and sunny, cool 15-20mph breeze. Coolant temp rises quickly. It goes right past the normal temp range right on up to the low 220's, settles, then climbs again to 235-239, stabilizes. Then for no apparent reason to me (regular driving, no AC on), it will shoot to the high 240's to high 250's (259!!! was the highest). The dash gauge climbed up to the red zone, threw the red light at me for about 10 seconds, then went off, and it cooled back to 235 and stabilized there. At stop lights, 240-245, then go green it's back down to 230's, occasionally low 220's, but never dropped below 221.
Most of the time, other than the spike at 259, the dash gauge showed right in the middle, so slightly above, even at 244 it was only slightly above the middle range. That just goes to show me that the dash gauge is worthless."
If you are using that factory temperature gauge on a D2 it will read "normal," needle in the middle and the coolant temp could very well be over 230 degrees. This is why there are SO many junkyard/recyclable D2s. People keep referring back to that damn dash cluster gauge for the oil and water but these are nothing but 3-position senders that read ZERO, average, and YOU'RE FUCKED! With that being said, if the needle starts moving up past halfway toward 12, its going to keep going all the way up. its not going to stall at say 2 o'clock position where you would think that its getting hot but not necessarily over-heating. Not the case with a D2 in that if the needle moves past halfway then the engine is already overheating, not "just starting to get hot."
If your needle ever hits the red in a D2 more than a couple of times, the possibility of the block cracking or cylinder sleeve coming loose is pretty good, nevermind the head-gaskets. We aren't talking about Toyota Camry or Honda Civic. The Rover V8 is one of the most poorly manufactured blocks ever put into a vehicle. 2003-2004 was the worst and whenever Ford or Tata bought it in 2005 they completely changed the Discovery and took this engine block out of production because it was junk and nobody wanted to invest in a total rebuild of tool and equipment used in the manufacture of the old V8 so they went with a new Ford-design used in Jaguar. LR had to replace so many of the 4.6s due to the oil pump and engine block failures that they practically ran out of replacement engines and everyone started taking up the slack making rebuilt short blocks with top-hatted liners from the originals that failed.
Just keep your coolant temps under 200 F and you do that by buying an aftermarket gauge and sender so you know exactly what you are working with.