Chaps,

My car is losing water but there is no warning on the OBC when the water gets low, is there supposed to be? Where is the sensor as I think I need a new one. Also, my water temperature guage keeps dropping to nothing like it's got bored of it's job and gone for a tea break. Occasionally it comes back to life. I've searched around and this looks like a bad sensor too but i can't find that one either...:rolleyes. This is not a good combination of problems with an aluminium motor! Cheers. Nick

http://bmwfans.info/original/E31/Cou/850Ci-M70/ECE/L/A/1992/06/mg-11/ill-11_1092/

Hi Nick have it pressure tested for leaks, also a good time to change the antifreeze.

Is there any puddles?

If you have a Coolant level sensor it should be in the bottom of the expansion tank.

The early 8's had one but the later models do not.

If you still have the light colored bottom expansion tank you will need to change it because they are a leak waiting to happen. The New style ones are all black.

My expansion tank is black but the car is early (Dec 1990), it's had a new radiator at some point and I guess the expansion tank must have been changed out too. So I'll just have to keep checking the water level until I work out where the waters going as I assume that means that there's no water level sensor (seems a bit mad as there are sensors everywhere on that car :confused).

There are no obvious puddles and I checked the conditon of all the main hoses and they look fine. One of the hoses to the aux heater pump came off in my hand so I re-attached that firmly, but there was no sign of a leak so who knows. Hope it's not the head gasket......but i mustn't be so negative! :nono

Top the car off with water, Run it warm and Bleed out the bubbles, Jack it up and look beneath the hose connections for leaks, Look for coolant runs under the hoses, As mentioned above, A pressure test will find it as well, Just don't over pressurize.

Do a gauge test.....If the gauges pass its time to replace all coolant sensors. The one on the radiator is for the aux fan. The one on the bottom of the expansion tank(where you fill & Bleed) is your level sensor. You have 3 more sensors on the back of the engine where your heater hoses are..take off the AC/Heat air filter housing to get access. You might find the leak there....also there's a bleeder hose under the radiator shrout..1 house comes from the thermostat, runs into a T , one end goes to the expansion tank the other end is connected to the top driver side of the radiator. Do your belts squeel? Water pump may be leaking.
Find the leak
If you don't see a puddle, check the bottom of the oil fill cap and dip stick if you have a milky residoo on it...then remove spark plugs and inspect for water dammage to your spark plugs....meaning? .........head gasket..if its a severe leak your car will blow white smoke like you never seen before..lol