As some of you already know I recently fitted one of the very nicely made, twin core, alloy radiators (one of these http://www.ebay.co.uk/itm/DIRENZA-TWIN-CORE-ALUMINIUM-RADIATOR-RAD-FOR-LAND-RANGE-ROVER-P38-V8-4-0-4-6-94/350591602189) and have been extremely pleased with it. But I decided to be a bit more scientific (anal?) than simply watching the gauge on the dash and the last few days gave me the chance to try it. Having one car that needed to be trailered to the south of France and another to come back, I sat the Nanocom on the passenger seat and monitored the coolant temperature. Now obviously we don't want an engine to overheat but it does need to be within the correct range. Running at a constant speed with ambient at around 22 degrees, it sat at 87 degrees, on that way back last night when ambient got down to 3 degrees, it had dropped to 86. Slogging up some of the hills, it crept up and the highest I saw was 91. Interestingly, giving it a big boot full of throttle so it kicked down and the revs were up at around 3,000 rpm, caused the temperature to actually drop rather than go up as I had expected so it proves the water pump and viscous fan are doing their job. On a long downhill with a closed throttle at about 70 mph and I saw it drop (as low as 79 on one occasion) as you would expect.

Then for the real test. The car I was bringing back had to be picked up on Saturday but I wasn't due to set off for home until Sunday (yesterday) afternoon so it had to be taken up to my mates place after we'd picked it up. Now he lives just over 2,000 feet up the side of a mountain and the access is a very narrow, potholed stone with the odd bit of concrete, forest track that rises 1,850 feet in two miles as it winds it's way up the side of the mountain, including two very steep hairpins. So with this

hooked up to the back, I stuck it in low (not a cat in hell's chance of getting up some of the steeper bits with that amount of weight on the back in high) and set off for the top. The temperature started off at 87 and started to rise as I made the engine work for a living. By the time I was halfway to the top, it was up to 94 but didn't go any higher and started to drop back as soon as I let the engine idle for a few seconds. That was all on LPG too when all the naysayers will tell you it'll ruin your engine as it burns hotter than petrol. Later we decided to check my mates P38 (another 98 GEMS only a 4.6 compared with my 4.0 litre). By comparison, his runs at 94 when running but rises very quickly when sitting in traffic to the point that the Nanocom got grossly offended when it hit 100 degrees compared with mine that stays at 87 no matter how long I left it idling. So we reckon that his cooling is a bit marginal and, as the water pump is new, his radiator is likely due for replacement in the not too distant but what should they run at? I think we can safely say his is running a bit too hot, or at least getting a bit hot when left idling but is mine running too cool?

Would running cooler be an issue? Isn't heat just a by-product?

Sounds like the radiator you fitted is good though. Would be interesting to have someone else fit one and compare the results.

As far as I know, you don't want to run too cool as you start to get inefficient combustion.

I swapped my old factory rad for a locally made one and, whilst I haven't put the Nanocom on it, over the months it's been on the gauge has only crept above half once and that was only by a hair after spending 2 hours to make 1.5kms in around 39 degree ambient. The old rad would have managed around 30 minutes, then climb steadily. So I'm happy with that.

Since my latest engine change, mine never goes over 1/4 of the way up the gauge. Would be interesting to know what mines actually running at, have LR opened up some of the water ways on there later exchange engines ? Hmmmm ! I’m certainly not pulling it apart to find out, I know the engine number was completely different to 60D,, that reminds me I must change it on log book, lol

The Thor uses two different temp sensors (in one sender unit) Chris. One feeds ECM and thus diagnostics, the other BECM and gauge. They differ in what they report. On mine, the temp gauge sits steadily at 5 to 12 and the Nano reports 95 to 100 degrees. Maybe your gauge is the other way round, or your stat is stuck open?
Gilbertd- using the thermostat figures, the GEMS is fully open at 88 degrees, so that's what LR think it should run at.
The Thor is more random as they state 85 degrees +/- 5 degrees fully open

I've looked into thermostat figures quite a bit, and have decided that frankly, they're bollocks!

As you say OB, RAVE lists two values based on year, but being +/- 5 degrees, making it anyone's guess as to what its actually starting to open / fully open at...

And there is only one part number available, which is presumably the later vague option, at this point.

Our red P38 has a genuine stat on it now and a new Nissens radiator after rebuilding it, and the rad doesn't start getting properly hot until 93+ celcius is indicated on the nanocom. That's with the fan removed too as a fair test with mine.

Mine has a cheap thermostat on it and the electric fan. The bottom of my rad is always hot, because its opening much earlier than the genuine stat, (and I don't have a constant source of airflow while stationary) - I'd say around 82-87. Which, interestingly, if you search for the proper part number and come across the cheap copies, is what they actually state as the opening temp.

So... vagueness all round. I prefer mine running slightly cooler via the coolant thermostat, as my fan thermostat lets things get up to 95 indicated before cooling off to 90-91. Underway, the fan doesn't come on unless crawling or around town. If I have a bit of a long downhill descent, the temperature does drop a bit until the stat closes back up fully.

That was all on LPG too when all the naysayers will tell you it'll ruin your engine as it burns hotter than petrol

It burns hotter than petrol but that's more than taken care of by the amount of heat dissipated boiling off the LPG in the vapouriser, surely?

No idea, but it might well do, particularly when working hard. I looked it up some time ago and providing the mixture is spot on (as it will run hotter if weak and cooler if rich) I found info that said petrol burns at 1530 degrees C and LPG at 1550 C so hardly any difference at all, not enough difference to worry about. However, I'm not sure if that is right as aluminium melts at a lower temperature than that which wouldn't do the cylinder heads or pistons a lot of good, although it does explain why running an engine with a weak mixture for a very long time will melt a piston crown.