Annoying check control problem?

[Hap]

right guys, my coolant light comes on whilst driving, mainly on longer runs, i have checked the levels and these seem fine, when the egine is cold the water level is adjacant to the mark levels on the expansion tank (the tank is the earlier one), but when i look when its hot, it appears to be about 15mm down. not losing water, temp is fine.

could it be the sender unit? fault in the check panel itself? pls help as it bugs the hell outta me/worries me and looks gay. It never used to come on before whilst driving? any tips?

ta

[wildeian]

maybe got an airlock in the system??

Try bleeding it.

[Brianmoooore]

Float on the sensor wrong way up? Wrong sensor fitted? Faulty sensor?

[Hap]

cheers guys, i fink it cud be air lock as the anti feeze was changed 300 miles ago when water pump done, but surely it shud b ok by now?

[Hap]

cheers so nothing to worry about? bled system.. this was done 300 miles ago when car was re antifrezed after water pump was changed, so surely it shud b ok or will air locks continue to persist?

[Geeman]

Did you end up taking it back to the guys who replaced your waterpump for you the other week?

[Hap]

yeah it was fine giles, no water leaks, pipes ok, no marks on floor pan, plus level was normal...i looked a rite twat.

[Geeman]

Sorry... but it was worth going just to make sure dude.

[Hap]

yeah must be just the sensor thats fecked or not workin properly

hap

[ceri325isport]

i had the same problem as you i had to pressure bleed it its fine now takes a while to do though once youv done it just keep an eye on it.

[Hap]

ceri325sport, i have recently had it reantifreezed, do you think the garage shud do it again free of charge since they put the fluid in etc?

[Hap]

ps from what the posts says it may have an airlock. will this clear up by itself with driving/releasing the cap , or will it need bleeding as stated above?

[ceri325isport]

thats all i know is mine was losing alot of water all the time i thought it mite of been the head gaske that was leaking but after i pressure bleed it its holding water fine if the garage did the fluid for you you should take it back to them as they did it id tell them the problem and ask them for a free diagnosis say if they can tell you whats wrong with the cra youl have the work done with them is it over heating alot afetr youv driven it for a while? whats the oil level and water level like?

[Brianmoooore]

OP says he's not losing water, and an airlock will send the temp gauge off the scale and crack the head in minutes.
There are small pockets of air that hang around in a M20 after it has been filled, which can take a few days to all come out, with the coolant level gradually dropping, nessecitating topping up a time ot two.
It's normal for water level to be different hot and cold, but as long as it returns to the same level every time it cools there's not a lot wrong.
Don't be too anal about keeping the water level exactly on the line. My daily driver 328 consistently stabalizes at about 1/2" below the correct level.
Not familiar with the very early coolant tank, but the water level in the later seperate tank and combined with radiator arrangements has to be way, way down before the lighr comes on.

[kirils]

... i have the problem with check controll, some times with the motorol light? the car is full with oil and the light sometimes comes on , than back off....
this is a pic of my car engine, has anyone seend this thing on the left before in another BMW? it's a spare ol reservoir?