E36 poor heater

[swansea v6]

I have just bought a 1997 E36 323i for shed money and although happy with the car this morning we had a very heavy frost. Jumped in car and turned on blowers to help melt the ice and even though the temperature gauge had reached normal the air coming out was cold?

The heating improved on the drive to work but now and again it would just go cold, then warm again? I have checked coolant level and that was fine, and other ideas??

[Buff Mchugelarge]

Check the water pump, it could be a plastic vaned jobbie on its way out.

That said, mine would only blow warm air when the dial was just to the left of the screen demist icon

[swansea v6]

Any easy way to check, or is just remove it?

[fushion julz]

Possibly you have an airlock in the cooling system...

When cold, turn ignition on and heater to hot..car should be level or front higher than rear
Remove radiator cap and also remove the plastic bleed screw beside it
Now slowly fill the radiator until no bubbles are coming out of the bleed screw
Refit bleed screw and rad cap and run till temp gauge in centre...air should be hot at full hot position.

If that doesn't work, but the engine doesn't overheat or the temp gauge move (it should be rock solid in the centre of the gauge when hot and running), then it probably isn't the waterpump....it may be a blocked heater matrix or a failed/failing water tap to the heater matrix (part 1 in this diagram http://bmwfans.info/parts/catalog/E36/Sedan/Europe...

Worth also checking that the gauge is accuarate and not giving a false reading.

However, if you have just got the car then consider changing the waterpump for a metal impellor type as the plastic ones do fail.

[rallycross]

the E36 have a cabin filter which become blocked and result in very little flow of air from the heater check this (flow of air would be weak but should still be warm).

[Dino D]

I had these symptoms and ended having a new thermostat and viscous fan coupling. A year later problem reappeared and this time it was due to failing bearings in water pump (had already been changed for a metal pump 2 yrs before).

The cooling systems really are as weak as they say. I advise having it checked out before it overheats on you.

[HustleRussell]

If there are no other symptoms then surely the heater valve is a prime suspect?

[swansea v6]

HustleRussell said:

If there are no other symptoms then surely the heater valve is a prime suspect?

Is that an easy job?

[HustleRussell]

As fushion julz described in his post, bleeding the system afterwards is the trickiest part of any BMW cooling system job- most of the components are easy to change. If I were you I'd change the cabin air filter first and then go from there, it's not too hard to diagnose this stuff by checking hose temperatures. The heater valve itself is easily accessible (on my E34, at least) and not difficult to remove/inspect/change. They have been known to seize up.

[HustleRussell]

ACTUALLY I've only just noticed the warm then cold bit in your original post. It is most likely an airlock, attempt to re-bleed the system.

[swansea v6]

Cheers will bleed the system later and see what happens!