5-Series (E12,E28, E34, E39, E60)Chat relating to the BMW 5-Series of all generations. Specific models include: BMW 518, BMW 520, BMW 520i, BMW 530i, BMW 528i, BMW 530i, BMW 518i, BMW 524d, BMW 525i, BMW 525e, BMW 528e, BMW 540i, BMW 535i, BMW 520d, BMW 525td, BMW 525d, BMW 530d, BMW 525i/xi, BMW 530i/xi. (BMW 5-Series Forum)
Hello everyone, I just bought my first BMW a week ago and I love it! One problem though, its a 98 528I with a million (209,000) miles on it. Perfectly maintained w/records. The weather here is around 20 to 30 deg, and at idle the car will never warm up. Once driving she is fine, and the blower cycles up and down correctly as needed. As soon as I come to a stop at a light first the passanger side blows cold then the drivers side. The engine temp is a perfect 12 oclock, except for one time when it went into the red at idle (clearly the thermostat got stuck). Any ideas on this heat problem. This car is new to me and this HVAC system is quite complicated. Thanks,
Well if it were me, I'd have it in to the BMW service department and their computer readings would tell them right away. But the first suspect is the the thermostat, if its red lined once, clearly there is something wrong with it.
But I can give you my experience with this problem, and you might not like it. There are two other causes of this (other than a sensor needing replacing), one is the heater core has become clogged, which doesn't happen on most cars but it did on my dearly departed Mazda Protege. This will restricted air from warming up, so since you car does warm up it might not be that.
The other your rings, if you are going through lots of oil and smoking a bit, you could have "blow back" which will affect your heating system as well..
Assume a good working system; once your temp needle reaches the half mark, the system had built enough pressure/temp to give you heat in the cabin. In fact when idling, engines tend to get hotter thus rise in coolant temp (this explains why your auxiliary kicks in -sensor dependant- when idling in traffic jams) all in all = hot air in cabin.
But when the thermo is stuck “open” it will take you forever to heat the coolant because “closed” is the default position of the thermo when cold so think 2 things are happening:
A. Less coolant for engine to heat up at cold starts=faster heat in cabin=closed thermo=no coolant circulation; period.
B. This "closed position" aid in building enough pressure/temp to get the system up and running=open (temp dependant)=entire HOT coolant is set in motion; your heater core included. Again assuming good working HCV
Note: Bad Heater Control Valve will ruin a wedding on a nice Sunday afternoon
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