coolant light on/off.

endautrestermes · Post by **endautrestermes** » Fri Dec 28, 2012 7:31 pm

so far, I can reply to these:

Stuart Truman wrote:It could be as simple as a sensor. Is the car misbehaving in any way? Running rough etc? Nope

No sign of oil contamination in the coolant? Nope
No sign of mayo in the oil filler cap? Nope

What's the temp gauge doing? (although iirc that's oil temp) Stable in normal temperature

not sure how to check this though:

Before anything else, see if the wire has come off the sensor. Although I don't know the zed specifically, a lot of these work by grounding the line when they overheat, so if the wire comes off and is flapping around it will short and the light will come on. I'd expect that to cause flickering on and off though.

by sensor, do you mean the little stick floating when removing the cap? or do you mean something electronic? ok I'll go look if I see any wire, just that I don't know where it could be

I'll check and come back, thanks again!

Stuart Truman · Post by **Stuart Truman** » Fri Dec 28, 2012 7:35 pm

The sensor is electronic. There will be a wire from it. No idea where it is though. Anyone?

Bleeding the system is probably next then I'd check with a dealer or indie on the cost of the sensor and thermostat, I'm more inclined towards the sensor and its probably the cheaper option.

Is the heater operating normally?

slick · Post by **slick** » Fri Dec 28, 2012 7:43 pm

The low coolant sensor is in the bottom of the expansion tank

Marius · Post by **Marius** » Fri Dec 28, 2012 7:44 pm

Stuart Truman wrote:The sensor is electronic. There will be a wire from it. No idea where it is though. Anyone?

Bleeding the system is probably next then I'd check with a dealer or indie on the cost of the sensor and thermostat, I'm more inclined towards the sensor and its probably the cheaper option.

Is the heater operating normally?

the sensors is on the bottom of the coolant tank , don't visible from the top,need to remove undertray to gain the access

endautrestermes · Post by **endautrestermes** » Fri Dec 28, 2012 9:00 pm

Marius wrote:
Stuart Truman wrote:The sensor is electronic. There will be a wire from it. No idea where it is though. Anyone?

Bleeding the system is probably next then I'd check with a dealer or indie on the cost of the sensor and thermostat, I'm more inclined towards the sensor and its probably the cheaper option.

Is the heater operating normally?

the sensors is on the bottom of the coolant tank , don't visible from the top,need to remove undertray to gain the access

thank you very much all, I'll check this sensor, see what happen

the heater is functionning ok, although the aircon is a bit weaker than it used to be (but that's something I noticed way before the coolant light problem)

Stuart Truman · Post by **Stuart Truman** » Fri Dec 28, 2012 9:55 pm

Sounds more and more like a sensor. If you had air in the coolant I'd expect the heater to be acting up. Likewise if the thermostat was faulty. I misread your original post and interpreted it as coolant over temp.

yg54sg · Post by **yg54sg** » Fri Dec 28, 2012 11:44 pm

i would fill it so you can see the water then do a couple of long high rev runs let it settle then check it the next day, it seems on mine after lots of high revs the water was dropping and the light coming on. I thought the worst head gasket but turns out to be a tiny crack in the expansion tank which gushes more water when the engine is worked hard and only when warmed up fully. Short runs /cold / low engine revs there is only a tiny amount of leakage so takes weeks to get the level to drop.

Dgutz646 · Post by **Dgutz646** » Wed Aug 14, 2019 10:57 pm

I m having a similar problem. I have a 2008 Z4 I recentally purchased and while checking the fluids I didn't close the radiator cap correctly. Next day all coolant is on the ground and I presume it's a broken hose or expansion tank but after inspection no hose or leaks are apparent. I bleed the radiator and put new antifreeze conclude the cap wasn't sealed correctly. I drive the day after and the low coolant light is turning of and off on occasion and I've already topped off the radiator. So I again look for leaks and none are apparent so I have no clue why the light turns on then off

z4dan · Post by **z4dan** » Thu Oct 14, 2021 6:46 pm

ben g wrote: ↑Wed Apr 18, 2012 7:08 pm the dash light has gone off after i added some water, so no worries there.

just don't know where my float has disappeared to

same happening to me today. in my manual it says be careful what coolant you use as the wrong ne can damage the engine

Scooba_Steve · Post by **Scooba_Steve** » Thu Oct 14, 2021 9:54 pm

z4dan wrote: ↑Thu Oct 14, 2021 6:46 pm be careful what coolant you use

Genuine BMW (isn't bad value as it can be diluted with tap water within hardness limits) or G48. There is a long list of approved but I've only seen the G48 here in the UK.

OE concentrate was cheaper than G48 ready mixed.

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