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View Full Version : Overheating mystery '06 325i 117k



mdefilip
09-28-2012, 03:44 PM
I have read a ton of posts about overheating 325s, but

First time was after 30 min of normal highway driving after sitting in airport parking lot for a week. Actually was pulling off interstate when orange temp light appeared followed almost immediately by the red temp. Pulled over immediately, let car cool and refilled the coolant as it was below min having blown out the cap. Restarted car and with no probs and drove like a church lady another hour home. No further problems, monitored coolant level and just assumed - having not happened again assumed I'd been low on coolant.

Next time was about 2 months later, at end of 4hr interstate trip. Orange light, then immediately red light. Hit shoulder as soon as was safe. Let car cool some. Again coolant below min having blown out cap. Had to add h2o as had no coolant up to min. Started no prob or additional warnings. Next exit filled up w coolant and got home without other hitches.

Have seen several posts about the car going into limp mode, not sure if this isn't happening to me or I've just stopped before I could notice.

Took car to local BMW specialty shops. Reputable but had not used them before having been going to dealership for CPO/extended warranty until recently. The shop was not able to find anything. No codes. None of the usual suspects typically associated with overheating or mentioned in other posts. No probs with pressure test and couldn't replicate overheating after several days with the car. Did coolant flush since I'd had to use water and sent me on my merry way with a gallon of coolant in my trunk.

Suggestions? Do I go spend couple hundred bucks for dealership to tell my same thing? Kind of at a loss. Thanks in advance.

mryakan
09-28-2012, 03:47 PM
Usually either a tsat or pump on its way out. If you have not replaced them yet, it seems you are due soon for that mileage.

White94RX
09-28-2012, 11:21 PM
Water pump. Guaranteed.

Jimmay84
09-29-2012, 05:18 PM
There is a weep valve on the water pump and it would be worth taking a look at it. If there are no obvious leaks the weep valve on the water pump is a good place to start! When the pump starts to go the seal breaks on the pump and drains your coolant. Also replace the tstat at the same time as the water replacement. Hope this helps

mdefilip
09-30-2012, 01:12 PM
Thanks for the suggestions, folks. Ah the fine line between failing parts and failed parts. Be preemptive or be on the side of the road. Thanks

02325
09-30-2012, 04:27 PM
There is a weep valve on the water pump and it would be worth taking a look at it. If there are no obvious leaks the weep valve on the water pump is a good place to start! When the pump starts to go the seal breaks on the pump and drains your coolant. Also replace the tstat at the same time as the water replacement. Hope this helps


you do realize that he has an electrical water pump not mechanical. They are totally different.

If its never had a water pump and t-stat, change them. I have seen cars overheat and leave no faults in the DME. Fom what i have seen and read the elec pump last an avg of 80k miles. If you got 110K out of it, than you got more than normal.

turbovrGTI
09-30-2012, 07:54 PM
you do realize that he has an electrical water pump not mechanical. They are totally different.

If its never had a water pump and t-stat, change them. I have seen cars overheat and leave no faults in the DME. Fom what i have seen and read the elec pump last an avg of 80k miles. If you got 110K out of it, than you got more than normal.

yep-had more than a few not set a single fault and come in on a tow truck.

Jimmay84
10-01-2012, 05:48 PM
you do realize that he has an electrical water pump not mechanical. They are totally different.

If its never had a water pump and t-stat, change them. I have seen cars overheat and leave no faults in the DME. Fom what i have seen and read the elec pump last an avg of 80k miles. If you got 110K out of it, than you got more than normal.

I did not realize they were electrical! I guess I am stuck on the old bmws when things were easier... Thanks for the info

bigturk
10-09-2012, 09:22 AM
Waterpumps on these cars have electronically driven NdFeB 3-step DC motors. Communication between the ECU and microprocessors in the pump's circuit board using the engine parameters (temp, pressure, etc...), the pump speed is infinitely varied. Basically car tells the pump when to run and how fast.

Circuit board inside the pump is highly complex, aerospace circuitry and connections. What you're seeing could be that the microprocessor or one of the connections is going bad.

Mine went out at 103k. Dealer had a 2 yr parts & labor warranty so that's what I used. $$ hurt but had to be done.

Good luck.