Thread: Super annoying low coolant alarm going off until car warms up (earth issue??)

Well I'm a little stumped at the moment. Took it back to the mechanic and he said that if there was some kind of air lock it would be carrying on in more ways than just the coolant alarm going off. He couldn't actually open the plug because it was too hot but he's confident it will have plenty of coolant in it and also my heaters and everything work fine. Then another mechanic friend of mine also said that if there was air in there it'd be overheating and not running well. It's not overheating and it's running very well.

Another option is a faulty sensor? Not sure, I'm looking into that.

Nothing has really changed that has done anything to that circuit, even had the guys who installed the lights and UHF look at it for a bit and they said they wouldn't have done anything that touched that.

I guess I can check if it's full at the thermostat first thing in the morning when it's cold, and now I have a replacement hex brass plug (with rubber o-ring) ready to replace it after I get that silly round thing off. But then I won't be able to open the one at the radiator with the sensor on it will I otherwise won't all the coolant pour out of there?

Might just have to get a new sensor, but it just seems to consistent for me to think that something is faulty with the sensor but everyone else seems to think the car is just fine.

Originally Posted by Young Angus

Well I'm a little stumped at the moment. Took it back to the mechanic and he said that if there was some kind of air lock it would be carrying on in more ways than just the coolant alarm going off. He couldn't actually open the plug because it was too hot but he's confident it will have plenty of coolant in it and also my heaters and everything work fine. Then another mechanic friend of mine also said that if there was air in there it'd be overheating and not running well. It's not overheating and it's running very well.

Another option is a faulty sensor? Not sure, I'm looking into that.

Nothing has really changed that has done anything to that circuit, even had the guys who installed the lights and UHF look at it for a bit and they said they wouldn't have done anything that touched that.

I guess I can check if it's full at the thermostat first thing in the morning when it's cold, and now I have a replacement hex brass plug (with rubber o-ring) ready to replace it after I get that silly round thing off. But then I won't be able to open the one at the radiator with the sensor on it will I otherwise won't all the coolant pour out of there?

Might just have to get a new sensor, but it just seems to consistent for me to think that something is faulty with the sensor but everyone else seems to think the car is just fine.

Get New Mechanics
These blokes didn't even physically check the system and just made guesses

Originally Posted by trout1105

Get New Mechanics
These blokes didn't even physically check the system and just made guesses

Well I hear you, but I also know they know these engines very well and have loads of experience with Land Rovers in particular the 300Tdi.

So let's say a 300Tdi had some air locked in the system, what actually happens to the engine when you start driving it around heaps? Does it just run as normal or will it misbehave?

Originally Posted by Young Angus

Well I hear you, but I also know they know these engines very well and have loads of experience with Land Rovers in particular the 300Tdi.

So let's say a 300Tdi had some air locked in the system, what actually happens to the engine when you start driving it around heaps? Does it just run as normal or will it misbehave?

First off have you fixed ALL the leaks yet?
Running about with low coolant levels because there is air in the system is Not a great idea, If it was we would all be doing it
Fix ALL your leaks then bleed the system yourself so that you "Know" that it has been done properly, Your 300TDI will Love you for it
Do you really want to cross the Nullarbor with a cooling system that you have doubts about?

Originally Posted by Young Angus

Well I'm a little stumped at the moment. Took it back to the mechanic and he said that if there was some kind of air lock it would be carrying on in more ways than just the coolant alarm going off. He couldn't actually open the plug because it was too hot but he's confident it will have plenty of coolant in it and also my heaters and everything work fine. Then another mechanic friend of mine also said that if there was air in there it'd be overheating and not running well. It's not overheating and it's running very well.....

That was my point re needing a bleed. If it needs to be bled again, it'd be overheating and in this case the dash gauge is almost sure to move.
It's the only time I get to see the gauge move.

Originally Posted by Young Angus

...
Another option is a faulty sensor? Not sure, I'm looking into that .... Nothing has really changed that has done anything to that circuit, even had the guys who installed the lights and UHF look at it for a bit and they said they wouldn't have done anything that touched that. ...

I'm more inclined to suspect wiring as a priority. Can you trace the wiring, or is a messy install?
Not saying that those guys stuffed anything, just that with the additional 'load' maybe it's playing havoc with the alarm thing.

Originally Posted by Young Angus

....
I guess I can check if it's full at the thermostat first thing in the morning when it's cold, and now I have a replacement hex brass plug (with rubber o-ring) ready to replace it after I get that silly round thing off. But then I won't be able to open the one at the radiator with the sensor on it will I otherwise won't all the coolant pour out of there?

Might just have to get a new sensor, but it just seems to consistent for me to think that something is faulty with the sensor but everyone else seems to think the car is just fine.

Definitely do the thermostat housing plug now you have a proper one.
Rip into the other one any way you can. A long-ish screw driver or piece of flat steel or something used like a lever bar across the slot isn't too hard to do. Hopefully when the timing belt mechanic redid it up when they bled it it's freed up enough for you to remove easily(ish).
They seem to 'weld' themselves on over time with non use. I think the heat-cold cycles tighten them up and makes them harder to remove .. why that design is so silly.

Wouldn't worry about the rad plug. When you remove the thermostat plug fill it up with water/coolant from there. Cap it finger tight so that you can undo it easily and then do the old drink bottle cut open and inverted on the coolant reservoir trick. Fill the drink bottle to above the height of the thermostat cap.
Keep adding coolant/water to the drink bottle so that it's always higher than the plug, open the plug to allow excess water to escape. I do it a few times(3, 4, 5 .. whatever), and you get the occasional air pocket come out of the bung.
I think the main issue on level ground is that the heater hoses are just a touch higher than the plug itself, so the extended height of water via the drink bottle method helps to get air out of the heater hoses.
If you can park the D1 slightly uphill, so that the heater hoses can be a bit lower than the thermostat bung it'd probably help a little too.

Originally Posted by trout1105

First off have you fixed ALL the leaks yet?
Running about with low coolant levels because there is air in the system is Not a great idea, If it was we would all be doing it
Fix ALL your leaks then bleed the system yourself so that you "Know" that it has been done properly, Your 300TDI will Love you for it
Do you really want to cross the Nullarbor with a cooling system that you have doubts about?

Leaks are fixed but have not bled it myself yet so I guess that's next. I've never bled the system so that's some good experience to add to the list for my trips

Originally Posted by AK83

I'm more inclined to suspect wiring as a priority. Can you trace the wiring, or is a messy install?
Not saying that those guys stuffed anything, just that with the additional 'load' maybe it's playing havoc with the alarm thing.

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Wouldn't worry about the rad plug. When you remove the thermostat plug fill it up with water/coolant from there. Cap it finger tight so that you can undo it easily and then do the old drink bottle cut open and inverted on the coolant reservoir trick. Fill the drink bottle to above the height of the thermostat cap.
Keep adding coolant/water to the drink bottle so that it's always higher than the plug, open the plug to allow excess water to escape. I do it a few times(3, 4, 5 .. whatever), and you get the occasional air pocket come out of the bung.
I think the main issue on level ground is that the heater hoses are just a touch higher than the plug itself, so the extended height of water via the drink bottle method helps to get air out of the heater hoses.
If you can park the D1 slightly uphill, so that the heater hoses can be a bit lower than the thermostat bung it'd probably help a little too.

Might try checking out the wiring, make sure they're good decent wires.

I actually emailed David from Engine Saver and he suggested taking out the sensor plug in the radiator and cleaning it with an old toothbrush and some Jif, so might give that a go before it warms up, also he said if I leave the header tank cap on there shouldn't be too much spillage...we'll see about that haha

Someone actually wrote somewhere online that they unbolted the whole header tank and just had someone hold it up higher than the rest of the engine for the bleed process so there was no mucking around with a coke bottle, I haven't actually looked yet to see how it's bolted on but kind of sounds like a nifty idea if it's actually possible.

Originally Posted by Young Angus

Leaks are fixed but have not bled it myself yet so I guess that's next. I've never bled the system so that's some good experience to add to the list for my trips

Perfect