Temperature and cabin heating

[sitrom]

Hi,

I own a BMW X5 2001 3.0i. Yesterday I went on a long trip in the snow (during which i was more that impressed with the car's performace and handling) however I run into a couple issues. As I was driving I noticed that the temperature gauge went off the scale passed the red indication. I immediately pulled over and went to check the engine over but everything was fine. As soon as I restarted the engine the temperature gauge was barely coming out of the blue region. I then drove the car for another 70 miles and the temperature gauge did not move out of the blue zone at all. I put that glitch (the gauge going of the scale) down to the freezing cold affecting the sensor or something because it happened within seconds. However I then noticed that I couldn't get almost any hot air out of the car's heater. And the temperature gauge was sitting quite low considering the car was driving at 70mph for about two hours. I would expect that the engine would warm up and the heating inside the cabin would work normally. I appreciate that the weather outside is below freezing (-10 to -6 C) however I don't know if it justifies the low engine temperature. One of my thoughts was that the thermostat may have been stuck open causing the fan to work all the time. Is that something that might happen? Finally, are there glitches something that are a result of the cold weather or would you recommend taking to the dealers for a check up?? One note that I need to make is that I have never seen the gauge half way apart from when I am stuck in traffic for a long time. As soon as I drive away the temperature drops close to the blue region. Attached is the photo that I took after I parked the car.

[5wany]

Had a similar prob year ago and it was the thermostat, but that was a vauxhall. Sounds like yours could be dodgy. Best get checked out as you dont want to ruin an engine for the cost of a few quid on a new thermostat.

[thedweeb]

I carn't help but thinking air lock altho' I may be wrong.... For the temp gauge to rise as high as it did theres either no water across the sensor or the stat has stuck closed and therefore the engine will "super" heat the water. If you're stating you had no cabin heaters whilst this was going on, then that leads me to think air lock as the heaters should be very hot if the stat had stuck closed.
For the car then not to get above the blue would indicate a stat stuck open.... My advise as already said would be to change the stat as you will need to blead the cooling system anyway so should remove any air lock.
Dweeb

[sitrom]

thank you very much for your comments. As mentioned the engine does not overheat despite the momentary indication where the temperature gauge went of the scale. I drove it for two hours after that and the car was fine. I would have thought that if the car was overheating it wouldn't last the two hours that I drove it. I am led to believe that the thermostat must have stuck open, causing the cooling system to work overtime and not letting the engine get to temperature. I guess I will have to pay a visit to the garage for some diagnostics.

[Bench]

Do you have the correct amount coolant/anti freeze mix?

[sitrom]

That is something that I haven't checked. I do know that the level is correct however, I cannot tell if the ratio is correct. Called BMW and they quoted me £400 for a replacement thermostat plus VAT. It seemed quite expensive to me. Maybe I need to look around a bit more.

[jas328sport]

Temp gauge reading that low would definately point to the thermostat being stuck open although no hot air could point at either an air lock or the water pump not working as it is the pump that pushes the hot water through the system including the heater matrix.
Definately needs looking at asap before any damage is done.