coolant temp cold in winter!!! - BMW Forum

justinbohn77 · 12-31-2008, 12:55 PM

So everything I have read so far deals with engines overheating at idle or becuase someone has changed their thermostat and improperly bled the coolant system. This is actually a little more fun than that so I hope someone can help me

I have a 99' e46 323i. In the summer it never overheats. Now it's cold (freezing) in Pittsburgh and my coolant temperature gauge is always reading cold when I'm driving around. If i turn the engine on and let it sit the coolant temperature gauge will rest in the center with no problem. But, once i take it out for a spin, again the temperature gauge will show coolant is getting cold. I thought that replacing the thermostat, flushing the system, changing the coolant and bleeding the system would fix the problem. NOPE!!!! It did not!!!! When it's really cold outside and I'm driving around that darn coolant temp gauge hangs out near the blue and then somtimes things get really interesting: It will show that the engine is overheating in the blink of an eye. The heat in my car works somewhat but the colder it gets outside the less heat I have in my car. In the summer the heat works great (HA HA) and I have no problems with my air conditioning in the summer either. What gives? any ideas????????

marti5 · 12-31-2008, 01:14 PM

Heater valves, where they are on a 3 series Im not sure, as I only work on 7 series and V8's, but ive had this on many 7's the valves get sticky over the years.

justinbohn77 · 12-31-2008, 01:32 PM

could you be a little more explicit in what you have had happen to your 7-series over the years? are we talking the exact same thing as what I'm experiencing right now? could you explain to me what you have had happen. You might be able to give a little more detail about what happened to you and I can check to see if I'm experiencing this as well. if this is the case is there anyway to prove for sure the heater control valve is the issue? Thanks for such a quick reply by the way

justinbohn77 · 12-31-2008, 02:27 PM

just doing a little searching and I'm curious? why would the heater control valve cause my engine coolant temperature to be cold? My idea for right now is to say screw cabin heat, I just want to make sure that the engine is running at it's normal operating temperature. Can the heater control valve cause the engine to run cold and then overheat all of a sudden? if so....... How?