Water Temp Fluctuation - Rising while driving. Normal when idling

[AWE46M3]

At the battery it should be 13.85 minimum and steady with engine running.

Battery tested at the source (vs head unit reading). 14.08v! All good there also.

[Slideways]

Has the needle always been in that position when the car is off?

[tlow98]

Should prolly do a leak down compression test as well. If the head lifted or warped temporarily there could have been some HG damage.

better safe than sry as once the HG starts to degrade you risk etching the iron block surface between the cylinders. It’s much easier to swap an HG than rebuilding the motor.

bummer about the raccoon incident. They can be big little beasts!

[AWE46M3]

Has the needle always been in that position when the car is off?

It has not - I believe the alignment got messed up due to the initial overheating episodes. After verifying temps were in the optimal range by putting the cluster in Test mode and checking with an OBD2 scanner, we knew the issue was cluster related. The old radiator hoses were blooming and browning from the inside and my radiator was the original one with 120K+ miles on it. It was time to replace hoses and the radiator. Water pump was good, but I wanted to replace it all to be safe and keep those components on the same maintenance schedule.

I assume the needle has been stopping at the center line for 20+ years. Deviating into the middle dot between center and Red did something to the alignment of the old needle gauge motor behind the instrument cluster. Likely an issue I'll have to fix if I overheat again in the future. Fingers crossed I'm all set for the next 60K miles.

Should prolly do a leak down compression test as well. If the head lifted or warped temporarily there could have been some HG damage.

better safe than sry as once the HG starts to degrade you risk etching the iron block surface between the cylinders. It’s much easier to swap an HG than rebuilding the motor.

bummer about the raccoon incident. They can be big little beasts!

Wrong thread? I avoided racoons for most of this process 😅

[sapote]

[B]2 part issue - initial overheating resolved by cooling system refresh. Water temp needle positon got thrown off during the overheating process and I needed to perform a gauge cluster reset to realign the needle. Everything is dead center after the cluster reset (video linked in my response) and the system is cooling perfectly..

If it was overheated bad enough for the temp needle to hit the end travel and stuck to the red zone, then I wonder if it's enough to affect the head and gasket? I don't know about the M3, but when my wife 325iT wagon overheated that the needle stuck to the red zone even when engine turned off, the event pull 4 head bolts off the block but head was still OK. I ended up added Timeserts to all thread holes and it was running like new until an idiot totaled it (left turned 45* into my lane from already stopped/disable position with hazard lights flashing on the right lane).

[Obioban]

If it was overheated bad enough for the temp needle to hit the end travel and stuck to the red zone, then I wonder if it's enough to affect the head and gasket? I don't know about the M3, but when my wife 325iT wagon overheated that the needle stuck to the red zone even when engine turned off, the event pull 4 head bolts off the block but head was still OK. I ended up added Timeserts to all thread holes and it was running like new until an idiot totaled it (left turned 45* into my lane from already stopped/disable position with hazard lights flashing on the right lane).

Sadly, agreed.

[bigjae46]

Sadly, agreed.

A 325i has a very different motor. Assuming it's an E46 then a 325i has an M54 which is an aluminum block and head. It is extremely common to have an M54 car overheat due to the extremely fragile coolant system - expansion tank, radiator, fan, thermostat housing, water pump are all frequent failure parts with a recommended replacement interval at 60k...its that bad! I've seen 4 BMW techs buy cheap E46s. I told them all, you got it cheap because it was overheated. Low and behold...all of them had to timesert the block. Its very easy to find an M54 in the junk yard, difficult to find one that hasn't been overheated. Most of them are at the junkyard because...they were overheated and people couldn't fix them.

Not really an issue with an S54 since it has an iron block. You can overheat it and then be OK. At this point, I'd drive it and see how stable the coolant temps are. If its running hotter then I'd say its time to pull the head.

[AWE46M3]

If it was overheated bad enough for the temp needle to hit the end travel and stuck to the red zone, then I wonder if it's enough to affect the head and gasket? I don't know about the M3, but when my wife 325iT wagon overheated that the needle stuck to the red zone even when engine turned off, the event pull 4 head bolts off the block but head was still OK. I ended up added Timeserts to all thread holes and it was running like new until an idiot totaled it (left turned 45* into my lane from already stopped/disable position with hazard lights flashing on the right lane).

I never went past the dot between red and center. This was the worst it got before I did the cooling system refresh (documented in posted 1). I consider this "overheating" - from what I've heard others share, this is within the acceptable range for coolant temps. It doesn't become a true problem until you reach the red zone (which I want to be abundantly clear I did not).

Appreciate you calling that out, but I want to clarify this point in case my quote lead you or others to a conclusion that may not surmise my original problem.






This is the furthest it ever went on me... and it was clearly not calibrated correctly when this was happening. That was fixed by the gauge cluster reset.

[sapote]

I never went past the dot between red and center. This was the worst it got before I did the cooling system refresh (documented in posted 1). I consider this "overheating" - from what I've heard others share, this is within the acceptable range for coolant temps. It doesn't become a true problem until you reach the red zone (which I want to be abundantly clear I did not).

"It has not - I believe the alignment got messed up due to the initial overheating episodes"

OK.
Somehow I thought the gauge needle alignment messed up due to it ran into the end zone and distorted. So what caused the alignment problem?

[AWE46M3]

"It has not - I believe the alignment got messed up due to the initial overheating episodes"

OK.
Somehow I thought the gauge needle alignment messed up due to it ran into the end zone and distorted. So what caused the alignment problem?

I found this thread that had a similar issue/resolution. The stepper motor/gears behind the needle can start to go bad, resulting the in needle gauge sticking. I was speculating it's been going to the center line for the last 20 years...the overheating sent it 1/4 turn further than it normally goes, possibly resulting in the alignment issue.

I'll look into sending the cluster off to have the motor replaced/rebuilt if the issue persists. For now, engine temps and gauge alignment are working as expected.

[0-60motorsports]

Anyone know if doing the cluster reset will mess with your cluster coding settings like CSL Oil level and warm up lights etc....