[wsouthb2]

Help please!!

My 2012 E93 335i N55 shows an overheat problem after about 20 miles of motorway driving. When it does this, the bottom radiator hose is stone cold. So i initially thought it must be the thermostat, so resigned my self to replacing the waterpump and thermostat. However, I then noticed that even from cold, the cooling fan was acting erratically various speeds etc...I've now found that if I start and drive the car with the heater control panel off, I do not get any issues and the bottom radiator hose gets nice and hot. Everytime it shows an over heat problem, I get a code "ECU has requested the electric water switched off due to blockage" I assume the blockage is the thermostat being shut? The most obvious question is has anybody come across this? Is it possible its the software in the heater panel corrupt? How does the heater panel interact with the thermostat? and any other answers you may be able to throw up. Car has done 70k miles and not sure if it's ever had water pump or stat. I should add, that with the heater panel on, although i know it will eventually go into limp mode, the heater and aircon all work fine.

[robthewrench]

You have the same blockage code that I got when my waterpump went out. It's the waterpump. Do the thermostat at the same time.

[wsouthb2]

Thanks for the reply dude. How sure can you be mate? I'm confused by the heater control panel situation.........

[Josegut303]

Hey guys any idea what the coolant capacity is on a 2011 bmw 335i n55 e90.? Also how exactly do you drain all the coolant out of the coolant system i remove a pipe connected to the water pump but that only gets about a gallon of coolant out.

[robthewrench]

Originally Posted by wsouthb2

Thanks for the reply dude. How sure can you be mate? I'm confused by the heater control panel situation.........

Based on the significant number of people who have the waterpump fail and also knowing that I've never seen a post about the control panel not working, I'm still leaning towards the waterpump being shot.

Nothing is for certain tho....

[PichaDis11]

Originally Posted by Josegut303

Hey guys any idea what the coolant capacity is on a 2011 bmw 335i n55 e90.? Also how exactly do you drain all the coolant out of the coolant system i remove a pipe connected to the water pump but that only gets about a gallon of coolant out.

2 Gallons. You'll need to drain the radiator too. There's a plastic drain plug to the bottom. Though you will not get the full 2 Gal out as the engine will retain a little.