Bmw mechanics

To any bmw whizzes my son has just purchased a 2005 320i e90 sedan 4cyl he’s just had the orange over heat light come up and has just replaced the water pump thermostat second hand rad as he broke his second hand fan switch and temp sender switch but after running short time the light is still coming back on he had a code for electric fan coolant temp sensor on live data the engine gets to 83 degrees and the rad outlet fan switch ? Reads 20degrees less any help on this as we have run out of things to replace

Did you bleed it according to the service schedule?

Hello saxman it’s been bleed and bleed some more

Should only need bleeding once, did you do it with the ignition on and the heater cranked to max? Sorry if this is an obvious question but some folks don’t realise to do this.

Fix it and dump it. They are an absolute dog. Even BMW workshops advise against them.

Don't you need scantool to bleed as its electric waterpump?

If it has an electric pump you can apparently activate it using the throttle pedal - with ignition on (Engine off) hold down Pedal for 10 seconds to run the pump for a few minutes.

nothing like an opinion that no one asked for.

4 cyl 2 L Be the N46b20 engine? - that’s mechanical water pump that’s mounted to the back of the power steer pump.
They are still a pain to bleed - they have electric circulation pump that pumps hot water through the heater core with the engine off if you want the cabin to stay warm.- you get air trapped behind this pump. The pumps on the left side chassis rail - unplug it and puts some volts on it you will hear it push the air through core. The other way is get the engine warm , shut the engine off and push the rst button on the right climate control knob- you will hear the pump start up and air push through the system.
See if pushing all the air out cures your issues.

Son had a "99 323i which the light would come on when water level dropped down in the thingy where the float switch contacts. If i remember right it was leaking at the radiator tank where that float switch sit in the return line [hard to explain]. Can't remember now what i did to seal it but had a fancy clip to get it off. But--big water leak was in a mushy hose straight down below that area i mentioned. I ended up shortening the hose [think it was maybe a heater hose or bypass hose [if such a thing]. I cut the mushy bit out & back to good stuff then bridged it with some alloy tube i found. Was only heater hose diameter 'sort of', maybe slightly bigger. If ya lean't over the left guard it was straight down in there below air filter stuff or whatever's in that area. That was a 6 cylinder 2.5.--one of a few problems, but was really nice to drive.
Just to add, [nightmare lol] the water was running off the plastic tray at the left rear of the gearbox [trans]. Tracing its origin was fun [not] with garage coming up with nightmare cost but just guessing worst case scenario's which was fair enough without getting into it. Was pretty happy to find what it was {& not at the rear of the cylinder head as suspected].

Thank you all for your reply’s I will try the heater pump thing and it is a mechanical pump