[Cooper9999]

Hi everyone

This is a cry for help as I’m at my wits end with my e91, it’s a 320d 2008 with an n47 engine

It was leaking coolant slowly for about a month or so, I put 1 can of radweld in to try and fix it, which failed so I kept topping it up until I got round to fixing it, whilst the coolent was leaking the heater stopped blowing hot air, even on the hottest setting, put this down to low coolent.

Anyway I found the leak which was in the radiator, so I bought a new radiator, flushed through the whole system, I flushed through the heater core whist I was at it, water came out nice and clear as it did with the rest of the system. I fitted the radiator, and topped up with coolent, I followed the instructions for bleeding it using the aux water pump (holding the peddle down etc) let it cycle through.

Everything has stopped leaking but I cannot get the car to blow warm air for any length of time via the heaters, I’ve tried burping all the hoses, I’ve re bled it again using the electric pump. I’ve tried opening up the bleed screw on the expansion tank, (only coolant came out no air)

I’ve also wired up the aux pump manually and let it run off a standalone battery for a while to see if that helps but still no change.

I’ve tried driving it about dor a couple of days and nothing, car gets up to and stays around 83/87c no problem.

Both hoses joined the core are hot

The heater will blow hot air for about 15 seconds before it slowly fades and gets colder.

Really stuck now, any advice on what I can do would be appreciated

[Stuiterbal]

Are you absolutely sure that you turned both the turn wheels in the cabin to hot (red), for both the front and rear seats? And the temperature settings are set to top temperature? (not just a few degrees higher)?

Are you testing with AC/compressor disabled? Does AC cooling otherwise functions correctly as well?

Does anything change if you try to use circulated or outside air?

[Cooper9999]

Yes both set as high as they will go, (28c not sure what this is in F - 80 something) air recirculating doesn’t change a thing unfortunately. Both of the wheels near the Vents are turned to red, I’ve tried with the ac compressor on and off, makes no difference

[Stuiterbal]

If there is initial heat, that would make me think there is a control/sensor issue. Can you inspect both the ambient and cabin temperature sensors? The cabin one can be dusted up.

Otherwise I'd have a read through of https://www.brakeandfrontend.com/bmw...peeds-repairs/

[Cooper9999]

Checked this today, ambient air temperature sensor working fine, I’ve cleaned out the little grill where the cabin sensor is and it’s not changed anything at all.

[Cooper9999]

Just in case anyone picks this up and is looking for a solution, I did finally fix this today, the fault was unfortunately with my heater core, I removed this today and slowly poured water into the inlet side and could see that it would take quite some time to drain down and through the core, my old core would hold about 180mls or water whereas the replacement could easily take 300mls and was very free flowing, I guess it was clogged with something that I couldn’t shift with flushing.

Managed to get older heater core out without draining the AC, and without removing the entire dash, I did have to cut the fan housing to give me room to remove the core, but was easily bonded back together when I’d installed the new core, and saved me hours in removing the whole dash.

My car is an 2008 e91 pre lci, it’s a 320d and it has dual climate control, it has the n47 engine, but took the Denso core replacement not the valero in case this helps anyone

It short a new core has fixed all the issues and I now have red hot heat!