Low Coolant alarm, but level looks OK.

[mojo]

Hi all, I'm getting a low coolant alarm in my D4. First time I checked it did look a bit low so I added some distilled water. The alarm disappeared for a while but came back, even though the level looks fine. I had it at the mechanics for another reason and asked them to check, and they reported a leak in one of the radiator pipes. But the level still looks fine when I pop the hood. I've now done a quick search on here and see that the sensors can have problems and need to be replaced occasionally, but there was no mention of that from the mechanic. I've booked in to get the radiator pipe replaced, but I'm thinking this won't fix my problem?

[DiscoJeffster]

Well they’re looking at the car not us, so it’s here to say they’re wrong, but I’d suggest you also ask them to fit a new coolant expansion tank at the same time to be doubly sure the problem is resolved.
There are many common leak points on these that an experienced Land Rover mechanic will know to check.

[CountOtto]

Hi all, I'm getting a low coolant alarm in my D4. First time I checked it did look a bit low so I added some distilled water. The alarm disappeared for a while but came back, even though the level looks fine. I had it at the mechanics for another reason and asked them to check, and they reported a leak in one of the radiator pipes. But the level still looks fine when I pop the hood. I've now done a quick search on here and see that the sensors can have problems and need to be replaced occasionally, but there was no mention of that from the mechanic. I've booked in to get the radiator pipe replaced, but I'm thinking this won't fix my problem?

I had the same issue after I had the rear pump belt replaced. I did read somewhere that the float sensor in the coolant bottle checks both the coolant level and specific gravity (concentration) of the coolant. I replaced a litre of coolant with concentrate and the problem did go away. However, I decided to replace the coolant bottle to be on the safe side.

[veebs]

Is your mechanic a Land Rover specialist / independent?

If not, i'm sure there are plenty of good options people can recommend in your area - they will know the quirks of these cars and possibly save a lot of run around

[mojo]

Yeah, they're a LR specialist. I guess I'll just assume the leak needs fixing, and ask them to replace the expansion tank as well.

[twr7cx]

Both our MY12 Discovery 4's had low coolant level issues not long post the timing belt change during which I replaced the water pump, flushed and replaced the coolant. Neither had an actual issue with the coolant level. I now make it part of the process to change out the coolant bottle as part of the timing belt job - I recommend the Meyle replacement bottles - they seem to be the pick for quality and price value.

[BradC]

I did read somewhere that the float sensor in the coolant bottle checks both the coolant level and specific gravity (concentration) of the coolant.

Yeah... nah.. The float looks at the coolant level. As the float ages it loses buoyancy, in between good and bad lies a state where the buoyancy sits between glycol and water and it kinda acts like a hydrometer. Alarm goes off, add glycol and it doesn't go off anymore. All that means is you've reached end of life on the float and pretty soon it'll sink even in 100% glycol. It doesn't measure specific gravity, it's just an increased SG makes it float a bit longer. It's still going to die.

You can't service the float. Replace the bottle.

[John_D4]

Hi all, I'm getting a low coolant alarm in my D4. First time I checked it did look a bit low so I added some distilled water. The alarm disappeared for a while but came back, even though the level looks fine. I had it at the mechanics for another reason and asked them to check, and they reported a leak in one of the radiator pipes. But the level still looks fine when I pop the hood. I've now done a quick search on here and see that the sensors can have problems and need to be replaced occasionally, but there was no mention of that from the mechanic. I've booked in to get the radiator pipe replaced, but I'm thinking this won't fix my problem?

That sounds like a common problem. I know that the coolant tank sensor does give up the ghost after a while. A replacement tank will fix the low coolant warning. You can’t fix the float, just replace the tank with a new one and problem should be solved

[veebs]

Yeah, they're a LR specialist. I guess I'll just assume the leak needs fixing, and ask them to replace the expansion tank as well.

Solid plan - any specialist will know about the saturated float problem, so if they say there is also a leak, there is probably also a leak.