E39 Cold air at idle

Hi my 1996 528 has recently started to omit cold air from the vents when at
idle, but warms up when the revs increase to above 1000 revs, I've filled
the expansion chamber until water comes out of the 2 bleed srews but it is
still the same.
Thanks in advance for any suggestions
Dean

replace water pump... they are junk with plastic impeller

"Dean" > wrote in message
...
> Hi my 1996 528 has recently started to omit cold air from the vents when
at
> idle, but warms up when the revs increase to above 1000 revs, I've filled
> the expansion chamber until water comes out of the 2 bleed srews but it is
> still the same.
> Thanks in advance for any suggestions
> Dean
>
>

"zz" > wrote in message
...
> replace water pump... they are junk with plastic impeller
>
> "Dean" > wrote in message
> ...
>> Hi my 1996 528 has recently started to omit cold air from the vents
>> when
> at
>> idle, but warms up when the revs increase to above 1000 revs, I've
>> filled
>> the expansion chamber until water comes out of the 2 bleed srews
>> but it is
>> still the same.
>> Thanks in advance for any suggestions
>> Dean

Partially correct, but... IMO, if that were the problem (bad water
pump) 2 things would happen differently: The engine would overheat
and it would *not* produce heat at higher rpms.

My guess would be the *auxillary* water pump is bad. That's the
little electric affair that is used to mnove heated coolant through
the heater core. When rpms are up the main water pumo (the one that
was mentioned as having a plastic impeller) builds up enough pressure
to get some coolant through the core, but at idle there is not enough
(hence the need for the electric one).

Now, even having said that, if you have never replaced your main water
pump before I would do so as they will self destruct (as zz said -
junk) and may well cause engine damage when it does if you don't catch
it in time.

-Fred W

Thanks Guys
as far as I know the water pump hasn't been replaced 119000 miles so
it's probably a good bet that it's on it's way out.
Thanks again
Dean

"Dean" > wrote in message
...
> Hi my 1996 528 has recently started to omit cold air from the vents when
> at idle, but warms up when the revs increase to above 1000 revs, I've
> filled the expansion chamber until water comes out of the 2 bleed srews
> but it is still the same.
> Thanks in advance for any suggestions
> Dean
>