Overheating on fwy with AC on during hot weather

[0-60motorsports]

Same 11v with new regulator installed?
I don't believe that the working stock alternator can't output enough current to keep the voltage at 14v when fan is running. I'm interested to see what the batt voltage is when cold engine idling with no fan running; I bet it's not 14v.

I'll do a full logging of the voltage when I get the car back. But bottom line issue resolved.

[sapote]

I did that and it was the same.

Same 11v with new regulator installed?
I don't believe that the working stock alternator can't output enough current to keep the voltage at 14v when fan is running. I'm interested to see what the batt voltage is when cold engine idling with no fan running; I bet it's not 14v.

[0-60motorsports]

11V means the old alternator has worn brushes (or bad internal regulator chips), so just replace the regulator and the old alternator should work with close to 14v output again, no need to replace with higher wattage alternator.

I did that and it was the same.

[sapote]

11

11V means the old alternator has worn brushes (or bad internal regulator chips), so just replace the regulator and the old alternator should work with close to 14v output again, no need to replace with higher wattage alternator.

[0-60motorsports]

Saw what? What was the measured battery voltage (whatever apps or blue tooth devices) with the stock alternator?

11

[sapote]

That's what we saw but I really discovered it through my battery monitoring app and Bluetooth device.

Saw what? What was the measured battery voltage (whatever apps or blue tooth devices) with the stock alternator?

[elrichmeister]

Nice work OP. I too have my water temp go high on hot days 95F+ with the AC on while on the highway. I will monitor my battery voltage. On my car seems like the previous owner has replaced it with remanufactured unit in the past.

[0-60motorsports]

Op, measures that batt voltage when the radiator fan running to cool down the hot coolant, AC on. Much lower than 14v will cause slow fan running.

That's what we saw but I really discovered it through my battery monitoring app and Bluetooth device.

[sapote]

Op, measures that batt voltage when the radiator fan running to cool down the hot coolant, AC on. Much lower than 14v will cause slow fan running.

[tlow98]

Well, didn’t see that one coming, but very happy you got it corrected.

[0-60motorsports]

Installed the 140amp X5 alternator and problem solved, before it used to go up to 98/99c and very quick. Nope it goes up to 94c and drops fast after.

Note the outside temp is an indicated 50c/122f! The angle of the pic is deceiving but the water temp gauge was right in the center. Ali this was done after a two hour test drive, mixed highway and traffic rush hour.


Basically the alternator was the culprit and not supplying ample current to the vehicle in order for it give full power and performance to the aux fan while AC was running (blower fan).


Sent from my iPhone using Tapatalk

[0-60motorsports]

I know I know, telling you to open your manual is as about as useful as telling you to turning it off and then back on again, but ive seen this sort of thread posted literally dozens of times, only for everyone to suggest to each other to replace every little thing in the car, only to have no improvable result afterwards. These cars do run hot, especially in hot weather, and nearly always when driven hard. I dont mind being the guy to tell you that perhaps what youre experiencing in 100+ degree weather might not be abnormal, just to save you from the wild-goose chase. But in the end you are just caring for your M, so I can respect that. Hope you resolve the issue, will be following.

Thanks I got it lol. And when I'm telling you it's not normal I don't understand why people aren't believing me. You want me to line up All the E46 M3s in a hot day and show you how stable the water temps are going to be in 125f temps and mine are going to jump to 98+ in under 5 mins of standing still amongst them? It's probably not possible to gather them all but I hope you get my point.

Any way hopefully we will resolve it this time. I'm done after four to five years of this issue. Time to show my car the love that I show my customers cars 👍🏼

[Thrifty S50]

I know I know, telling you to open your manual is as about as useful as telling you to turning it off and then back on again, but ive seen this sort of thread posted literally dozens of times, only for everyone to suggest to each other to replace every little thing in the car, only to have no improvable result afterwards. These cars do run hot, especially in hot weather, and nearly always when driven hard. I dont mind being the guy to tell you that perhaps what youre experiencing in 100+ degree weather might not be abnormal, just to save you from the wild-goose chase. But in the end you are just caring for your M, so I can respect that. Hope you resolve the issue, will be following.

[0-60motorsports]

Has any one here opened their owners manual? Im just going to leave these here...



Im not saying that its isnt a good thing to be concerned about "rising" oil/water temps, but rising indication on the gauges are not necessarily abnormal. Some cars gauges creep up, some do not. I do wonder if the gauges had this characteristic when the cars were new off the lot, however I would wonder why BMW would include these provisions within the manual if they didnt.

That was funny 🤣

[Thrifty S50]

Has any one here opened their owners manual? Im just going to leave these here...



Im not saying that its isnt a good thing to be concerned about "rising" oil/water temps, but rising indication on the gauges are not necessarily abnormal. Some cars gauges creep up, some do not. I do wonder if the gauges had this characteristic when the cars were new off the lot, however I would wonder why BMW would include these provisions within the manual if they didnt.