Overheating Issue

[Usmc1028]

I'm going to try to explain this the best I can. I have a strange overheating issue. It only seems to overheat when my heater is off, and when the gauge does start to go up, right when I turn my heater on its goes right back to normal. When its on, it does just fine, never goes past center. Things ive already replaced: thermostat, water pump, expansion tank, lower and upper hoes, cap, bleed screw, transmission thermostat, drain plug. Another strange thing, I can leave the car sitting at idle, and it wont over heat, it only happens when i start to drive it and even when i start to drive it, takes about 15-20 miles before the temp starts to go up. I've bleed the system multiple times, no luck. Any clue what it could be? Heater core? Water valve? Temp Sensor?

Also i currently do not have any A/C pressure in the lines right now due to a motor swap. Could that have anything to do with it, if im correct, one of the A/C lines are connected to the heater core.

2006 BMW X5 3.0

[Usmc1028]

No one?

[tmv]

Thread starts in the early morning. We don't wake-up that early however. Give it some time.
How did you bleed the system? Cooling System Bleeding
Did you unlock the cluster and see what the engine core temp is, when the temp needle went up? If it's in normal range and the temp needle went up, you have bad sensor.
Engine under load would generate more heat. That's why your X is fine when idling since the engine is relatively cool.

[TerminatorX5]

even though you bled the system, i bet there is still an airbubble somewhere... do the bleeding on an incline - there are procedures here and bimmer forums... if not an airbubble, then your system is not water/air tight - something is siphoning...

[racingbmwm3]

how many miles? sometimes a blocked or very old radiator (dirty) can cause similar symptoms, its just efficient enough at idle to radiate off the excess heat, but the extra heat of driving is just enough to push it past its peak efficiency. And thus the heater core makes up for that little bit of extra heat and keeps the system from overloading.
Can you unlock your instrument cluster to see the actual engine temperature, or use an OBD connection to do the same? I suspect that even with the heater on, its still running slightly hotter than normal, but it happens to be within the range of 'normal' so that the cluster shows it at the middle mark.

[Usmc1028]

Ive bleed the system 4 times already. This last one, doing it with the front jacked up a little bit. Motor has 83k body has 94k including radiator. The radiator seemed to be flowing good when i had it out of the x5. I hope its just the temp sensor.

Today after bleeding the system for the forth time this time on a incline. Started the x5 from a cold start heat was off. Once i seen needle reach center, i turned on the heat and the needle dropped about 2cm back down. All the BMW ive worked on ive never seen this happen before when i do a bleeding procedure.

Thanks for the replys.

[Usmc1028]

At idle its sitting at 111c and with heat on it drops to normal range of 92-96c. There def something wrong.

[racingbmwm3]

Have an infrared heat gun to do spot temperature measurements? You'll have to remove the electric fan to do this, but take spot measurements all over the radiator to see if it has hot and cold spots. should be almost uniform in temperature. If you have colder spots in the middle or scattered around it, then its the radiator.

[Usmc1028]

Well at least i know its not my temp sensor. Ill swap out radiator with my dads x5 see if this fixes anything. If not i may have a big prob here. So yall dont thing having any a/c pressure in the lines is causing it to overheat.

[upallnight]

Originally Posted by Usmc1028

Well at least i know its not my temp sensor. Ill swap out radiator with my dads x5 see if this fixes anything. If not i may have a big prob here. So yall dont thing having any a/c pressure in the lines is causing it to overheat.

Nope.

Did you have the manual or Automatic control? Heater control should be at full max heat when you are doing the bleeding.