MORE HELP!! Coolant light staying on - full expansion

S

sk93

Veteran
 Nottingham
right.. expansion tank changed, all hoses reconnected, cable reconnected to sensor at the bottom. no obvious leakage anywhere.

refilled with ready-mixed coolant to the max level, opened the bleed screw halfway, turned ignition on (didn't start car), turned heater to max heat, turned fan on to the first click (lowest speed), continued to top up coolant level to above max until it stopped going down and constant coolant came from bleed screw.

tightened bleed screw, replaced cap, started car.

engine warms up as expected, but coolant light comes on after about ten seconds of ignition and remains on.
car heats up and holds at around the straight up position on the dial - doesn't rise further.

stopped engine, waited for it to cool, checked level and it's fine (just about max mark - where I left it effectively).

restarted engine and same situation - coolant light comes and stays on.

dafuq is going on? what have I missed here??

:headbang: :headbang: :headbang: :headbang: :headbang:
 
ordered a new one from eurocrapparts for collection tomorrow am.. simple to swap out, and only a tenner, so fingers crossed!!
 
sk93 said:
right.. expansion tank changed, all hoses reconnected, cable reconnected to sensor at the bottom. no obvious leakage anywhere.

refilled with ready-mixed coolant to the max level, opened the bleed screw halfway, turned ignition on (didn't start car), turned heater to max heat, turned fan on to the first click (lowest speed), continued to top up coolant level to above max until it stopped going down and constant coolant came from bleed screw.

tightened bleed screw, replaced cap, started car.

engine warms up as expected, but coolant light comes on after about ten seconds of ignition and remains on.
car heats up and holds at around the straight up position on the dial - doesn't rise further.

stopped engine, waited for it to cool, checked level and it's fine (just about max mark - where I left it effectively).

restarted engine and same situation - coolant light comes and stays on.

dafuq is going on? what have I missed here??

:headbang: :headbang: :headbang: :headbang: :headbang:
Click to expand...

You did what?

If you don't start the engine the water pump doesn't move, the engine doesn't heat up, the stat won't open and you can't bleed out the air!

Running the heater fan will not circulate water around the cooling system. You should leave the heater control on max heat so as not to airlock the heater matrix but you'd be unlucky to get an airlock there anyway.

You need to run the engine with the cap off until up to heat so the stat opens, then you'll see the level drop. Top up until level is stable, replace cap and keep bleed screw open until no more air bubbles come out.

Go for a spin then try bleed screw again. Check level next day when cold and top up if necessary.
 
no no no.. you never start a BMW when changing the coolant!

turning on the fan to low and setting the heat to max without starting the car opens the thermostats and engages the water pump sporadically.
this forces the coolant through the entire system correctly without risking starting a car with an airlock.

I guarantee this is 100% correct procedure, but can't find the proof yet!
 
here's the TIS linky :thumbsup:
http://translate.googleusercontent.com/translate_c?depth=1&ei=EN7hUMDzEOqY2wXU04DABg&hl=en&prev=/search%3Fq%3Donline%2Bbmw%2Btis%26hl%3Den%26client%3Dfirefox-a%26hs%3DbQ6%26tbo%3Dd%26rls%3Dorg.mozilla:en-US:official%26channel%3Dnp&rurl=translate.google.ca&sl=ru&u=http://tis.bmwcats.com/doc1080540/&usg=ALkJrhhw5hU6x-zskCAzWt5dnhqgR48xeg
 
sk93 said:
no no no.. you never start a BMW when changing the coolant!

turning on the fan to low and setting the heat to max without starting the car opens the thermostats and engages the water pump sporadically.
this forces the coolant through the entire system correctly without risking starting a car with an airlock.

I guarantee this is 100% correct procedure, but can't find the proof yet!
Click to expand...


Mmmm. I find it hard to believe that opening the valves on the heater matrix without starting the engine can also open a mechanical thermostatic valve or indeed turn (sporadically or otherwise) a belt driven water pump. :o
 
Some quick googling shows that M54 engines use a traditional belt-spun waterpump and would need the engine operating to move coolant, whereas the N52 engines use an electric one and would be able to move coolant without the engine operating. I don't know if the Z4 M54/N52 differs but it's an important distinction.
 
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