Z3 heater, good at times...

[TriumphZ3]

Hi y'all, sorry for thinking out loud here on a very cold Friday morning without actually looking over the car but just wondering about the heater system in my 1998 Z3 1.9. It's normally very very good and I've commented on that before now, but the frost is here and it seems to be clearing the windscreen on the passenger side only, not the driver's side. I've felt the air coming up and it's warm on the passenger side but cold on the driver's. Any idea why, and what should I look for? I can also idle the car all morning with the thermostat reading normal temperature but the heater cold so the screen doesn't clear at all, until I drive for a mile or two then it comes on fully. Is this normal?

 

[TriumphZ3]

Just to update - been out this morning, engine at full 'normal' temperature and heater freezing. I'm assuming the entire heater system is hidden behind the dashboard?

 

[Fender2004]

You may have air in your water system and just need to removing it to allow the warm water into the heater?

 

[TriumphZ3]

You may have air in your water system and just need to removing it to allow the warm water into the heater?

Any tips? The heater came on yesterday as I was driving but I needed a good 20 miles at motorway speeds before getting any heat at all. The engine heats up - according to the gauge - and I've replaced the thermostat when I bought the car, but the heat doesn't seem to be transferring to the heater as readily as it once did. All help welcome!

 

[Fender2004]

These cars can be a pain to get all of the air out to give you a warm heater. If you lift the front of the car to help with the air movement. Then I always disconnect the top hose from the radiator and turn it 90 degrees by loosening the clamp on the other end of the pipe, and then fill the coolant slowly till it’s full, then fill the radiator slowly until it’s full I use a flexable funnel. Then reconnect the top hose and start the car, and loosen the bleed screw on the top of the radiator, till any air comes out then tighten the screw, and hopefully you will be sorted.
Hope this helps.

 

[Pond]

Just beware of the BMW temp gauge; it is a 'rough guide' at best. I would put a decent code scanner on and see what coolant temperatures that is saying.
Is the coolant expansion tank full when cold?
If it was OK before and there are no coolant leaks I can't see it suddenly getting airlocks.
Have you run the car up to temperature at standstill, checked the stat is opening and checked everything is hot?
It could be that your heater matrix water valve is sticky, or got a bad connection so is preventing coolant circulating through the matrix.

I don't know the 1.9 engine but the coolant system on all are very similar.