[LotusBMW]

Got this warning light. Thing is I noted the day before that there was a large fluid dump on the ground under the car, no doubt the cause. By the time I'd got to it it was semi dry and on a sloped and porous surface so not 100% clear. I did however taste it and it was v unpleasant so not water, probably coolant. Had a big glass of water after!

So to me it's strange that it did it while stationary in the driveway. You'd think if something in the cooling system was to let go it would be under pressure? Perhaps I got lucky and it let go the last time I drove it into my drive.

Thoughts on causes? Water pump was done a few years back by the PO.

I think I'll just truck it down to the workshop...

[DR-JEKL]

It could simply be a split rad tank or radiator. (very common for these items to fail and split/leak)

Try and have a look at the bottom of your rad reservoir or radiator for signs of leakage?

If you need a new radiator the BEHR branded radiator (OEM) is very cheap from FCP euro (by memory $350-400 AUD delivered)

[EB89]

As DR J said, look at the coolant expansion tank on the left hand side of the engine bay, is it covered is white dry stuff?

The tank is prone to cracking.

To get by, top up with distilled water.



If its not leaking, look elsewhere for coolant thats dried

[Rdany]

My coolant expansion tank split from top to botom few days ago. And the only signs I got was a small leak few days before that on the front drivers side after turning the car off. Was a nasty experience.

[SE7EN335]

For the N54 platform, there are a few coolant leakage prone areas. Like DR-JEKL said, the radiator is hugely common especially in earlier models that are coming near 100k kms or above (mine has a leak and will be changing shortly). The coolant expansion tank is another common leak point, upper and lower coolant hoses to the radiator as well, and also the hose that connects to the oil cooler from the radiator is notoriously prone to coolant leak especially at the connection to the oil cooler, where excess heat wears it out over time fast. Also the O-rings on the turbo coolant feed and return lines can crack over time and cause minor leaks especially on older cars.

If you are going to change your radiator, might as well change those hoses in one go to save labour and time.

[Socket]

Originally Posted by SE7EN335

For the N54 platform, there are a few coolant leakage prone areas. Like DR-JEKL said, the radiator is hugely common especially in earlier models that are coming near 100k kms or above (mine has a leak and will be changing shortly). The coolant expansion tank is another common leak point, upper and lower coolant hoses to the radiator as well, and also the hose that connects to the oil cooler from the radiator is notoriously prone to coolant leak especially at the connection to the oil cooler, where excess heat wears it out over time fast. Also the O-rings on the turbo coolant feed and return lines can crack over time and cause minor leaks especially on older cars.

If you are going to change your radiator, might as well change those hoses in one go to save labour and time.

+1 S7
Coolant hoses are amazingly expensive
Be warned

[Testercles]

I had a massive leak cause by the vent nipple snapping on the top of the expansion tank.

[Khy335i]

What a coincidence!

I got this exact warning light on my dash on the weekend. It was a little strange considering I had only added new coolant in a few months ago.

Dropped by the mechanic and he attached something to the coolant box which applied air/water or something into it, during this test, sure enough, there was a leak in the coolant box and water was running out during each pump

Got the coolant box replaced for $250 + 30 mins of labour

All seems good now!