Coolant Low level alarm but level normal

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ktm525

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No idea on the LR3s but there is no float inside/attached to the tank on the LR4s. The float is the thin vertical black piece that the sensor is attached to. When you buy a sensor it comes with a float/sensor together. This is what the wires plug into. See two posts up for the diagram from the service manual. You do not need to replace the entire tank to replace the float, although the dealer may tell you that. They are about $15.

Capture1.PNG
 

bbyer

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In the LR4 version pictured above, does the vertical black "stick" get wet?
If so, there must be some sort of gasket located at the base of the sensor or in the hole at the bottom of the tank.

From my reading of other LR3 expansion tank posts, (and perhaps my misunderstanding of them), I presumed that there was some some sort of a separate float within the tank that surrounded a tall plastic "dimple".

My assumption was that on the LR3 version, there was no water seal required for the sensor as it merely slide up inside the hollow dimple and was able to sense the float location thru the plastic. In other words, the sensor remained dry all the time.

I guess when my old tank is removed, I will be looking at it and will report back as to what I determine, plus pictures.
 

ktm525

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Yes the vertical black stick is in the tank. There is a rubber seal at the base that prevents the tank contents from leaking.
 

John Robison

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Change the whole tank, as others have suggested. Both Jaguar and Land Rover are prone to this, as they use the same tank. We see it all the time
 

rjowenusa

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I had the same issue on an LR3. I replaced the sensor but the 'low coolant' warning would still come on, usually once the car warmed up. The sensor is actually two components, the 'stick' sensor that fits into a void in the bottom of the coolant tank and a 'float', fitted inside the tank around the void that floats on the coolant. The 'stick' sensor is not actually in the coolant and can be changed without draining coolant. The 'float' component becomes less buoyant over time and warm coolant is less dense than cold coolant so eventually the float no longer floats, especially when the car is warm. If the fault is intermittent and mostly when the car is warm (at least to start with) its time to change the tank (no way to change just the float). If the fault is constant then you could start with the sensor. That said, an OEM tank with sensor included isn't that much more and covers all the bases.
 

bbyer

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My independent installed the new coolant expansion tank in my LR3 today and all good - the low fluid level warning no longer displays.

The fluid level setup is per the previous post, a sensor that is removable but inserts into a dimple on the underside of the tank and does not get wet per the newer LR4 tank design.

There is a separate float that gets wet and moves vertically in the fluid and is dependent upon fluid level. I guess the float eventually soaks up the coolant, gets heavy and stays at the bottom or at least does not rise sufficiently in the hot fluid. When the fluid is cold, the sensor tends to not alarm so that suggests the float is affected by fluid temperature. Perhaps the specific gravity of coolant reduces as temperature rises.

In the first and second jpg's, the float is the light coloured item behind the F500 numbers on the tank. The tank is on its side in the jpg and hence the float moves to the right as fluid level rises. What this means that if the fluid level alarm goes on and all is working as it should, there is not much fluid in the tank.

The third and forth jpg's show the connector end of the fluid sensor.

Expansion Tank float sensor and float a.jpg Expansion Tank float sensor and float e.jpg Expansion Tank float sensor and float h.jpg Expansion Tank float sensor and float c.jpg
 

bbyer

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Only JLR would use a float that saturates with coolant. Junk
To give LR some credit, I guess on the LR4 they decided that was a problem rather than a parts opportunity.

As to heavy floats, I am on about my third float in my Marvel Schebler carburetor in my airplane. Over the years the float has been changed from a welded hollow brass shape where in some situations, the weld of the halfs had pinholes that over the years would allow gasoline inside.

The fix was the new wonder plastic float that turned out to be some variation of the LR float. I suppose the LR float did not like gylcol; the Marvel Schebler plastic did not like gasoline.

The third float is also plastic, but is space age plastic, so time will tell.

And yes, ignore the Airworthiness Directives and in time, the engine stops. Usually one is in flight when this occurs and gravity being very reliable, takes over.
 

rjowenusa

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I have to admit to being slightly nervous at present. After finally taking the time to fix the erroneous 'Low Coolant' warning, I have no warning lights or other fault messages on any of my three LR's. Something is sure to go horribly wrong very soon!
 

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