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I know the thermostat is supposed to open at 88 degrees, but mine is obviously opening sooner than that. As mentioned a few days ago, my temperature gauge has gone intermittent and as I had a trailer towing trip over to France last week, I plugged the Nanocom in to keep an eye on the temperature. Seems I'm running at a steady 85 degrees, saw 87 once while slogging up a hill and 81 when coasting down the other side but even after being stuck in traffic for an hour (in the UK, that sort of thing doesn't happen the other side of the Channel), it sat at a steady 85-86, never getting any hotter than that. OK, so I've got the Direnza alloy radiator that has 50% greater capacity than standard, it's filled with the required 50/50 mix of Ethylene Glycol anti-freeze, a relatvely newish (about 3 years old) Airtex water pump and a two year old viscous coupling. So the cooling system is in good nick but is running at these sort of temperatures something I need to do anything about?

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Mark Adams at Tornado Systems offers a D2 Hot Climate stat with the necessary pipe work to make it fit a P38. That runs it 10 degrees cooler and he swears by it and has done a lot of testing and performance mapping on cars running it so I wouldn’t worry if you’re only a few degrees cool.

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I'd be more worried if it was running closer to 100 degrees and relying on the pressure to keep the boiling point down. More wondering what sort of temperature range is acceptable.

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Mine sits at 97c

But from what I recall the Thor runs hotter, for efficiency and emissions reasons.

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Mine runs at 83 - 85 on the highway, 87 around town and on a 35 degree day (and humid) and stuck in traffic, around 92. Add about 2 degrees if running A/C. I haven’t touched the cooling system in my ownership which is over 2 years, so no idea if it is original or how old the components are. The hoses are soft though so I assume at some stage they were changed.

Speaking to Mark Adams, he said that mine seemed to be “a good one”.

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I think you have nothing to worry about.
After spending tons of kms made with 95-108 degrees and equivalent tons of sweat and worry (would often see 115/117), when my fan disintegrated, I took matters in my own hands (alienating my former "pal-mechanic") and replaced absolutely EVERYTHING (except couple hoses which are bidding their time).
Never saw more than 85-87 deg. afterwards, and 90-92 when at standstill in the heat with the AC on ... which makes me think most stories about the RV8 "too hot" are mostly due to (normal) deterioration of the water cooling components over time, and neglected until the inevitable comes.

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On the site I visit for the Disco (landroverforums) there’s lots of talk about temperature. Anywhere between about 85 and 93 seem to be normal.

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This can vary a lot depending on your source of thermostat...

I had a cheap aftermarket one on my V8 that was clearly stamped as an 82c stat on the actual thermostat metal body inside the plastic housing. It would never really get above 88c with the viscous fan.

The genuine LR ones though I have reliably seen run a lot hotter - not being reasonably well open until 95-96c.

Note - RAVE specs two temperatures for Thor and GEMS... however only one part number is available for the thermostat, and in my experiences, its certainly the hotter end. Nothing else controls engine temperature - so RAVEs figures are meaningless.

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Actually spark plugs / temp sensor can effect engine temp along with rad condition Thor / gems different rads Injectors lambda sensors ---- gems runs hotter than Thor --- strange that 🤔

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Eh? Spark plug temperature has very little to no impact on the engines overall temperature...

The temperature of the coolant is dictated by the thermostat - yes a blocked up rad will make it run hotter if its pushed hard or the ambient temp is high, but that isn't a variable you should be considering. If you're rad is in that poor a shape - its no longer fit for purpose.

Temp sensor has nothing to do with it - that reads the coolant temp. Nor do injectors or oxygen sensors.

I haven't looked in a while but I thought it was actually the Thor stat that had listed a higher opening temp. Can't remember.

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Also - an upgraded rad won't cause any engine to run cooler than specified under normal operating conditions within the manufacturers design and specs because again - the stat controls the temperature by varying or cutting off the flow through it entirely. If you're standard radiator is, under normal situations, failing to keep the engine cool, its blocked either internally or externally preventing good airflow - it isn't a fault of the radiator sizing or design.

Sure, uprating it can certainly give you increase cooling capacity, which you might find beneficial in hot climates under heavy load - at which point the stat is likely going to be fully open and staying that way. But under normal situations, it is hardly necessary. The P38 radiator is huge as standard. I'm not saying I wouldn't have one - they're certainly more robust, and now that I use a GEMS radiator setup in my M57 powered P38, I could drop one in if I wanted.

Just look at some of the custom engine setups the Aussies and yanks do - far more powerful turbo diesel and V8 applications than a P38 will ever see, with comparatively small radiators and electric fan setups.

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Looks like the replacement stat I fitted about 7 years ago is an 82 degree one then. I needed a new radiator some time ago, the one in it (may even have been the original) did the job as you would expect until I was going uphill, towing about 3 tonnes in summer and the gauge started to climb. Putting the HEVAC on Prog so it went to full heating bought the gauge back down confirming the rad was only just flowing enough when things got critical. That was when I fitted the Direnza as it was around £160 at the time, so not much more than a standard replacement so it seemed like a good idea. I've towed up to the 3.5 tonne limit in ambient temperatures up to 40 degrees so keeping the cooling system up to scratch isn't such a bad idea considering what can happen if it isn't.

But it does sound like running at 85-86 degrees isn't going to do any harm and gives me plenty of headroom if things do start to cause it to run a bit hotter.

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my experience with the cooling system in rovers in general is quite good , the only things that cause temp rises is worn impellers on water pumps blocked rads or the fins have rotted (generally copper core rads). thermostats can be a problem but they generally work or dont work , most thermostats have the temp stamped on them , also dont discard a bad earth to the engine, this can really screw with your temps
Question , with anti freeze how dose it work when the anti freeze bit evaporates at around 75 dec when thermostats run at 82+ dec . do you have a specific thermostat for colder areas ?
PS i dont think i would like running my motor at that lower temp, not very efficient?

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mad-as wrote:

Question , with anti freeze how dose it work when the anti freeze bit evaporates at around 75 dec when thermostats run at 82+ dec . do you have a specific thermostat for colder areas ?

Huh? Neat Ethylene Glycol has a boiling point, the temperature at which it will evaporate, of 197 degrees C, so if mixed 50/50 with water, with a boiling point of 100 degrees C, that means the coolant will have a boiling point of around 149 degrees. But that is at atmospheric pressure and the reason the cooling system is pressurised is to raise the boiling point even further. Hence you can often run at 120 degrees without it boiling over as long as the pressure cap is good and it doesn't spit the coolant out (then you overheat due to a lack of coolant). That's why running on plain water isn't a good idea as, other than it corrodes the engine and clogs the waterways, it has a lower boiling point that an anti-freeze mix.

No idea what the spec of this orange OAT stuff they recommend for the Thor is though.

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Main difference between the two is the corrosion inhibitor, the Oat stuff is supposed to be good for 5 years, the blue one only 2 years. Downside to the oat one is that it's not compatible with some materials, I think copper is one of them. And obviously mixing them isn't recommended either.

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Gilbertd wrote:

mad-as wrote:

Question , with anti freeze how dose it work when the anti freeze bit evaporates at around 75 dec when thermostats run at 82+ dec . do you have a specific thermostat for colder areas ?

Huh? Neat Ethylene Glycol has a boiling point, the temperature at which it will evaporate, of 197 degrees C, so if mixed 50/50 with water, with a boiling point of 100 degrees C, that means the coolant will have a boiling point of around 149 degrees. But that is at atmospheric pressure and the reason the cooling system is pressurised is to raise the boiling point even further. Hence you can often run at 120 degrees without it boiling over as long as the pressure cap is good and it doesn't spit the coolant out (then you overheat due to a lack of coolant). That's why running on plain water isn't a good idea as, other than it corrodes the engine and clogs the waterways, it has a lower boiling point that an anti-freeze mix.

No idea what the spec of this orange OAT stuff they recommend for the Thor is though.

on the bottle it says anti freeze anti boil , you explained the boil part (that bit we know) but the bit that stops it from freezing is what i was asking , if it boils out at 75 deg and the car runs at 82 deg then its no longer anti freeze , so how dose it do the two jobs when one part is over cooked, so to speak, bye the other part
in other words is it one or the other . i dont live in this type of climate and i dont use it ,i just use inhibitor. so how do you stop it freezing without the plug in heater system i hear of occasionally. so how cool is to cool:😀 the other end of the story.

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Ethylene glycol has a freezing point of -12.9C and a boiling point of +197C. When mixed with water at a 50/50 ratio, the freezing point is depressed further to -45C. It is the same compound acting as antifreeze and anti-boil, not two different products, so given its high boiling point it isn’t going to vaporize at 75C. Even if it did, it is trapped in a closed and pressurised system, so as soon as the system cooled, it would return to a liquid.

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Is it supposed to have 50/50 mix of water and antifreze? Water has a higher specific heat capacity than antifreze, so a cooling system with a greater water:antifreze ratio has better cooling capacity than one with a higher ratio of antifreze.

Another thing I'd check is mixture but I expect you have ;-).

Again none of this should affect temp because the thermostat controls temp... but if the engine is going to get hot due to pushing the cooling system with the stat open it's more likely to get hot with more antifreze in the mix and leaner mixture.

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Yes it is, from the manual:

enter image description here

If it was running hot, I'd be checking the mixture but as it is running cool (and still doing the usual 200+ miles per tank of LPG), I don't think it's running rich. Point is, it isn't getting hot, after idling for over an hour it had crept up to 87 degrees and no hotter when slogging uphill with a trailer on the back.

Seems that it's running cool but not too cool so I'm happy with that. I'll have to check it again when the ambient is much higher just out of curiosity.

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Let it idle with the viscous fan removed and you'll soon see it creep up - I bet you with it in place, you'll almost never feel the bottom of the radiator get hot - short of after a run as you say up hill with a heavy load.

It's because the fan always moves so much air while free wheeling that as soon as the stat opens a little bit, enough heat is rejected through by the radiator with the airflow that it pretty much closes up again or is open jussssst enough to let enough coolant pass at idle and keep things in check.