Water Temp Fluctuation - Rising while driving. Normal when idling

[sapote]

Do you recommend doing a full system flush and seeing how system performs thereafter? Thinking about flushing the system and maybe installing a new radiator - my current radiator appears to be the original one and may be gummed up.

On radiator gummed up, if the thermostat housing inner surface looks clean with minimal mineral scale built up, then I would expect the same for the radiator. If the overheat issue happened only recently then I don't think the the rad could change this suddenly. I'm thinking Tstat or e-fan failed (low chance on water pump).
Try to clean the debris on the rad and condenser fins.

[AWE46M3]

sapote , Obioban , Casa de Mesa , bigjae46

8/2 Update: 80 degrees and sunny weather in So Cal.

Replaced the radiator, water pump, aux fan switch, radiator hoses, and installed high temp o-rings on all connecting points. Besides the O-Rings (bought from WOLFN8TR ) all parts are OEM BMW.

My water temps are still off center. Not as bad as they were before (nearing the middle dot), but off center. Temps return to center when I turn the heater on and allow the heater core to evacuate some hot air. The temps are normal until I turn the AC on, and then they begin to creep off the center line.

Car running, AC on - apologies for the glare, taken while driving.


Car running, AC off, Heater On:





I installed a new temperature sensor and thermostat last September and have about 3K miles on the car since those were replaced (OEM BMW).

Clutch fan was obstruction tested and appears to be running full power (could not be stopped by rolled up newspaper test). I am not sure where to go from here.

I had my alternator replaced before all of this started happening (also OEM BMW). The alternator is showing 13.3-13.7v when operating (reading this from my Avin head unit). I've never hit 14v when cruising. I am wondering if the alternator is not providing enough power to the aux fan. See Post 55 from this thread - member installed a 140A X5 alternator and it fixed his cooling issues when his AC was on.

Could this be my alternator not powering the aux fan sufficiently since all other major components and points of failure have been replaced?

Open to any and all suggestions for next steps to take. Car is driven modestly around town and it is ~80 degrees out. I expect more from this cooling system...

[Slideways]

Did you replace both coolant temps sensors, one under the manifold and the lower radiator hose one?

[bigjae46]

Also, did you turn the heater to the highest temp and fan on low when refilling the coolant? This circulates coolant through the heater core loop and gets any air out.

and check the bottom front of the condensor…that is usually beat up. Might be so beat up it’s reducing air flow through the radiator.

[AWE46M3]

Did you replace both coolant temps sensors, one under the manifold and the lower radiator hose one?

I’ve replaced oil/coolant sensor 13621433076 last summer.

13621433077 was replaced yesterday. Both have been replaced. Thank you for calling that out

[AWE46M3]

Also, did you turn the heater to the highest temp and fan on low when refilling the coolant? This circulates coolant through the heater core loop and gets any air out.

and check the bottom front of the condensor…that is usually beat up. Might be so beat up it’s reducing air flow through the radiator.

I’ll verify that. The condenser was cleaned before the new radiator went on. No major damage or notable issues other than typical patina due to age.

If the process you’re suggesting was not completed, the system self-bleeds, doesn’t it? Any manual bleeding just expedites that process - is that correct?

[nextelbuddy]

can you post a pic of your cluster temp needle when ignition is off?. it would be interesting to see your needle placement when at rest. if anyone has ever touched the cluster for work involving needles, ten they could be off after being reinstalled or bumped by accident from other work when cluster was open.

[bigjae46]

I’ll verify that. The condenser was cleaned before the new radiator went on. No major damage or notable issues other than typical patina due to age.

If the process you’re suggesting was not completed, the system self-bleeds, doesn’t it? Any manual bleeding just expedites that process - is that correct?

There’s a check valve in the pump but it’s probably doesn’t fully seal. So you get some drainage from the heater core loop which introduces air. So unless you get flow through that loop you’ll probably have air. It might eventually bleed itself but it usually results in a slightly higher reading especially if it causes the coolant level to drop enough.

[sapote]

"There’s a check valve in the pump"
I think you meant the Tstat.

[sapote]

[I had my alternator replaced before all of this started happening (also OEM BMW). The alternator is showing 13.3-13.7v when operating (reading this from my Avin head unit). I've never hit 14v when cruising. I am wondering if the alternator is not providing enough power to the aux fan. See Post 55 from this thread - member installed a 140A X5 alternator and it fixed his cooling issues when his AC was on...

1. Did the e-fan run when the gauge needle passed the center?
2. Use a genuine voltmeter and measure the battery voltage at various engine RPM. 13.3 to 13.7v variation is not normal.
3. Can you check the engine temperature using INPA or any OBD reader to verify the dash gauge when it passed the middle center?

[Anri]

Do you recommend doing a full system flush and seeing how system performs thereafter? Thinking about flushing the system and maybe installing a new radiator - my current radiator appears to be the original one and may be gummed up.

Hi,

Seems like you are still with the same issue.

If you want to resolve your over heating, reach out to me, bring me the
car and I will fix it. You are not the first one I have fixed the same
issue you have..

I am in Los Angeles area


Regards
Anri

[AWE46M3]

can you post a pic of your cluster temp needle when ignition is off?. it would be interesting to see your needle placement when at rest. if anyone has ever touched the cluster for work involving needles, ten they could be off after being reinstalled or bumped by accident from other work when cluster was open.

Cluster has not been touched. It returns to the center line when the AC is off, so I suspect it is not a cluster alignment issue. I appreciate you mentioning that thought - it would suck to spend all this time and money chasing a cluster needle alignment issue...haha.

1. Did the e-fan run when the gauge needle passed the center?
2. Use a genuine voltmeter and measure the battery voltage at various engine RPM. 13.3 to 13.7v variation is not normal.
3. Can you check the engine temperature using INPA or any OBD reader to verify the dash gauge when it passed the middle center?

1. Yes
2. Copy that - what is the correct range when the car is running? The head unit is not perfect, but it is giving me a ballpark. I saw the head unit hit 14v with my Valeo alternator, but that thing whined like a supercharger and had to be returned. I went OEM BMW. No lights flickering or other issues to note but I am seeing a relatively low voltage reading for my liking.
3. That has not been done, but will be done this afternoon. I'll report back.

Hi,

Seems like you are still with the same issue.

If you want to resolve your over heating, reach out to me, bring me the
car and I will fix it. You are not the first one I have fixed the same
issue you have..

I am in Los Angeles area


Regards
Anri

I'm heading your way if I can't figure this out!

[sapote]

F2. Copy that - what is the correct range when the car is running? The head unit is not perfect, but it is giving me a ballpark. I saw the head unit hit 14v with my Valeo alternator, but that thing whined like a supercharger and had to be returned. I went OEM BMW. No lights flickering or other issues to note but I am seeing a relatively low voltage reading for my liking.

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

[AWE46M3]

nextelbuddy - nailed it. It was the cluster. I think something happened behind the scenes with the motor or needle alignment when I began overheating initially.

Needle alignment with the car off:




Temps test with the car in test mode. Car reading mid -80 degree celsius but the needle was well into the hot range...




Performed a gauge cluster reset and it re-aligned the needle (link to youtube video).

[AWE46M3]

sapote Pklauser - thank you for calling out verifying coolant temps despite the needle's position. That helped me resolve this one.


bigjae46 - thanks for taking the time to offer some great suggestions for bleeding - followed all of those steps this afternoon and even topped off the system after noticing it had bled quite a bit.

Anri - Thank you for offering to take this on and fix it! Glad to have you as a local resource.

Appreciate yall!