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SO after owning my land discovery sport 2018 for literally just over a month, my low coolant light came on today. I commute 5 days a week from the Long Beach area to Beverly Hills (I work in bev hills) and I take a winding road that has hills so that possibly could be it? My car is still under warranty so I think I’ll check that out.
 

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It looks like electronic system of Land Rover Discovery Sport is very poor designed. I got 2015 Land Rover Discovery Sport and engine maintenance light constantly coming up , took it 6 times to garage and no one knows what it is? Garage replaced 3 parts and the same problem.
I am having the same engine light issue with my discovery 2015 too. Also coolant level warning since a week now. Where you able to get rid of the engine light? I brought the car to Canadian tire for oil change , they said coolant level was not low. I don't know if they are false warnings
 

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The low coolant warning is very sensitive and a small drop n level will cause it to give a warning.

Mine had come on early in ownership and level looked fine but adding 250cc of water ended the problem.

OOPS IT SHOULD HAVE READ 250 ML
 

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Isnt it somewhat dangerous to overfill the coolant? My light keeps going on and off during long drives. And the coolant level hasnt changed as far as I can tell. It appears to be at the upper limit. I'm happy to add a bit more, just to make the error go away. But I dont want to overfill it either.
 

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BTW, coolant won't easily evaporate by itself as cars are designed to seal the coolant. Any mechanics who say "it can evaporate" are all BS. It only evaporates when its sealing is faulty. Scientifically, the alert happens when 1) leaking, 2) faulty sealing, 3) faulty/sensitive sensor, 4) low temperature (contraction), 5) and some other rare problems in cooling system.

I had a few coolant level alerts on winter but it was gone after a few minutes. So it was 4) to me. (I know cars... so I closely monitored engine temp while the alert was on. If it goes up, everyone must stop the engine.)
 

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When a car is operated on a hot day and the engine has been run for a long time pressure will build up when car is shut down. The engine block is hot and causes coolant temperature to rise as well as pressure. The "rad cap" will open to relieve the pressure and some vapour may escape and it is almost like evaporation. With newer cars the rad fan runs to help cool down the coolant after shut down.

I always let my engine run for a short time after a long highway drive, lets coolant temperature stabilize and more importantly lets the turbo cool down as well.
 

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When a car is operated on a hot day and the engine has been run for a long time pressure will build up when car is shut down. The engine block is hot and causes coolant temperature to rise as well as pressure. The "rad cap" will open to relieve the pressure and some vapour may escape and it is almost like evaporation. With newer cars the rad fan runs to help cool down the coolant after shut down.

I always let my engine run for a short time after a long highway drive, lets coolant temperature stabilize and more importantly lets the turbo cool down as well.
AFAIK, when radiator cap opens, the coolant will just flow into its reservoir thru hose. If everything is sealed properly, there won't be any evaporation in the process. It is simple law of conservation of mass. The coolant won't go anywhere, and it must be kept in the cooling system. Some very minor evaporation might happen a little bit over time because the sealing can't be always perfect. But it should be very minor.
 

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Ahhh if you take the time to actually look at your car you will see there is not actually a rad cap on the Discovery at the radiator. The rad cap or pressure relief cap is located on the reservoir itself.so if the valve opens it is then vented to the air. Take a look and you will see the pressures are stamped on the reservoir cap.

years ago the coolant was vented into the reservoir and then sucked back into the rad as the temperature dropped. The pdf is for the Diesel but same test is used for gas.
 

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Ahhh if you take the time to actually look at your car you will see there is not actually a rad cap on the Discovery at the radiator. The rad cap or pressure relief cap is located on the reservoir itself.so if the valve opens it is then vented to the air. Take a look and you will see the pressures are stamped on the reservoir cap.

years ago the coolant was vented into the reservoir and then sucked back into the rad as the temperature dropped. The pdf is for the Diesel but same test is used for gas.
Ahaha, now are going pretty deep. Let's be nerdy together!

1) First of all, you brought a very right point that Disco uses expansion tank instead of overflow tank. That's why there is no radiator cap. I didn't realize that.

2) Yes, again, expansion tank cap is supposed to vent the air once it reaches to the limit. If my argument sounded like "the cooling system must be vacuum-sealed", that is my bad. It is not, it can't, and, more importantly, it shouldn't be. I just meant "properly sealed". It might explode someday if it is vacuum-sealed everywhere. The system can hold the pressure to a certain level for sure, but it needs to vent after the limit.

3) Yes, again, because the vented air contains some of evaporated coolant, we would lose some small amount of coolant. So my arguments "there won't be any evaporation in the process" and "The coolant won't go anywhere" are misleading. I want to rephrase those as "there won't be any significant evaporation in the process if the system works properly" and "The coolant won't go anywhere under normal conditions if the system works perfectly." I will explain those in the next.

4) If there is too much coolant, the expansion cap will vent the air. So we lost some of the coolant. If we repeat this process, we would lose more coolant again and again. In the end, we would reach to an 'optimal' amount of coolant naturally. In that status, the overall pressure of the system would stop at just below the maximum. It won't reach to the maximum easily now as there is less coolant to expand. This is what I meant "The coolant won't go anywhere under normal conditions if the system works perfectly.". Now the cap won't vent anything, so the law of conservation of mass persists.

5) Even though the cooling system works perfectly, under certain conditions like long/fast drive on a very hot day, you will lose the coolant anyway. However, that is something minor you can just top off coolant on 1 year/10,000miles maintenance. Less than half inch mostly. Also, very likely you won't see any alert too unless you have faulty/sensitive sensor. Most garages will do it for free if you pay for oil change service. This is what I meant by "there won't be any significant evaporation in the process if the system works properly."

6) However, if the cooling system doesn't work properly (i.e. can't cool the engine down effectively) with some reasons, the temperature will keep going up, expanding more, increasing pressure, and making the cap to be vented. Now even though you don't have enough coolant, it still expands too much due to overheating. So you will see the alert. You add more coolant. But you didn't address the cooling system issue. So you will lose coolant again and again. In the end, you will see the alert again very soon. This stupid repeating adding and losing coolant is not expected in the proper cooling system. This happens when your cooling system is out of order.

7) So, yeah, if the system works perfectly, it won't evaporate. And if the system works properly, it won't evaporate easily at least. That's why I mentioned that any mechanics who say "it can evaporate" are all BS. By accepting that, you will end up losing coolant unnecessarily, see the alert frequently, have to keep adding up more than once a year. It is better to find the root cause. That said, I do understand that it is a quite difficult, painful and time-consuming job to find a minor leakage. So lazy mechanics just give up and say "just top-off". But some experienced guys are able to identify the cause fairly quickly and give you a peace of mind.

Sorry for being nerdy. But I believe we all can learn something from this :)
 
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