Coolant Temp High At the Track. Maintenance and/or upgrades?

[MPowerZ32]

Hi all,

My E46 M3 experienced high coolant temp at AutoClub Speedway in Aug. I started noticing coolant gauge pass 3/4 dot and reaching the red dot in the second and third sessions. The ambient temp was high around 105 degrees. I had to short shift and ease off the throttle to avoid coolant gauge going into the red zone.

In terms of relevant mods, I'm running Turner Motorsport underdrive pulley set including the water pump pulley and CSF oil cooler. My oil temp seemed to be fine on track. The rest of the cooling system and fan setup is all stock. I'm curious outside of flushing coolant and switch to 60/40 water/coolant mix, whether hardware upgrades are called for. I've also been looking at electric fan conversion. I'm not sure if I should be concerned about my lightweight battery not being able to support the fan. Any input would be very much appreciated!

[pMak26]

If your coolant temp was high but your oil temp is low, you have an issue. Either you have no ducting to your rad or your rad is plugged up. My stock rad has no issues keeping coolant temp in a happy range while the oil is another story. I also have underdrive pulleys and a lower T-stat; Not a big enough mod to make a massive difference. I did ditch the mechanical fan because I like blades not flying through my hood, but the fan makes no difference when you are out on track moving above 40mph. I put an oversized electrical fan in and ditched the AC fan (and the AC) then ducted all the air from the front openings to the rad and oil cooler.

[MPowerZ32]

pMak26 Thanks for chiming in! Your first hand experience with the on-track coolant temp is super helpful! It does sound like my coolant system is not working as efficiently as intended. I will start with fresh coolant, making sure no air is in the system.

[bigjae46]

I'd check the water pump by removing the thermostat and looking into the impeller.



But 100% distilled water and some water wetter cools better and faster. Also safer for others if you have a coolant leak.

An electric fan will actually hurt cooling at higher speeds since it creates turbulence on the backside of the radiator and reduces airflow through the radiator.

[sc_tr0jan_m3]

I'd check the water pump by removing the thermostat and looking into the impeller.



But 100% distilled water and some water wetter cools better and faster. Also safer for others if you have a coolant leak.

An electric fan will actually hurt cooling at higher speeds since it creates turbulence on the backside of the radiator and reduces airflow through the radiator.

Do folks really run their electric fan while on track?! 🤦♂️


Sent from my iPhone using Tapatalk

[S14]

Hi all,

My E46 M3 experienced high coolant temp at AutoClub Speedway in Aug. I started noticing coolant gauge pass 3/4 dot and reaching the red dot in the second and third sessions. The ambient temp was high around 105 degrees. I had to short shift and ease off the throttle to avoid coolant gauge going into the red zone.

In terms of relevant mods, I'm running Turner Motorsport underdrive pulley set including the water pump pulley and CSF oil cooler. My oil temp seemed to be fine on track. The rest of the cooling system and fan setup is all stock. I'm curious outside of flushing coolant and switch to 60/40 water/coolant mix, whether hardware upgrades are called for. I've also been looking at electric fan conversion. I'm not sure if I should be concerned about my lightweight battery not being able to support the fan. Any input would be very much appreciated!

What tune are you running?

[bigjae46]

Do folks really run their electric fan while on track?! 🤦♂️


Sent from my iPhone using Tapatalk

Even if you're not running the fan, deleting it resulted in a decent cooling gain of about 10 to 15 degrees lower.

[MPowerZ32]

I'd check the water pump by removing the thermostat and looking into the impeller.



But 100% distilled water and some water wetter cools better and faster. Also safer for others if you have a coolant leak.

An electric fan will actually hurt cooling at higher speeds since it creates turbulence on the backside of the radiator and reduces airflow through the radiator.

I just did a coolant flush to run 10/90 anti-freeze and distilled water. In the process I also installed motorsport thermostat. Unfortunately I did not check the water pump while I was in there. That would be the next thing if my current measures do not solve the problem

[MPowerZ32]

What tune are you running?

I run OEM tune with ECU SMG adjustments. Nothing custom in terms combustion parameters

[MPowerZ32]

Updates on recent cooling system work:
1. Flushed the cooling system and filled 10/90 water/antifreeze + 1 bottle of water wetter. I was running 50/50 water/antifreeze before.
2. Remove debris stuck in the AC condenser and straightened bent fins to improve airflow
3. Removed the aux fan

I do not have custom oil and coolant temp gauges. So the following observations are from the OEM gauges:
1. It takes much longer now to warm up the oil and coolant.
2. Street driving around 70 degrees ambient temp, it takes 10 miles to get oil gauge to the 1/4 spot, and coolant near 1/4 spot.
3. Extended highway driving the oil temp is around 165 degrees, coolant is between 1/4 and 1/2.
4. Oil and coolant temps vary quickly based on car's movement
5. If car is stopped and idles for an extended period of time (10 mins), coolant can get to 3/4. This is not optimal. Oil temp still stays under 210.

I'm sure on the track i will see improvements due to car movement. Observation 5 probably means my aux fan removal has greatly reduced the car's ability to cool when not moving. In CA I'm worried about coolant temp when stuck in traffic on a hot summer day. I'm thinking about converting my clutch fan to electric and use the aux fan controller. Would that be a reasonable / correct approach to improve cooling at zero or low speeds?

Thanks!

EDIT: typo on the water/antifreeze mix. I'm actually running 90/10 water/antifreeze

[S14]

The overheating you observed in #5 is from lack of airflow. The stock clutch fan almost always moves more air than electric fan conversions.

Your issue is the CSF radiator. swap it for new OEM, that drastically reduced my overheating on track. Also, 50/50 distilled water/antifreeze will absorb more heat than your current 10/90 ratio. In CA where it never gets cold, you could run 90/10 distilled water/antifreeze + water wetter and probably be good to go.

Edit: shifting at redline will exaggerate your overheating issue. See if shifting earlier in the rev range helps keep your temps under control on track.

[ken o]

Check the impeller on the water pump. The fins can begin slipping in housing and no circulating the coolant. I had this happen to two different OEM water pumps. I switched to a water pump with metal impellers. Also adding a real water temp gauge, The OEM gauges are crap and buffered.

[CrookedCommie]

You will need an electric fan to keep the car from overheating when stopped. It's fairly easy to bolt in a SPAL fan to the stock fan shroud and wire it to the aux controller.

[MPowerZ32]

The overheating you observed in #5 is from lack of airflow. The stock clutch fan almost always moves more air than electric fan conversions.

Your issue is the CSF radiator. swap it for new OEM, that drastically reduced my overheating on track. Also, 50/50 distilled water/antifreeze will absorb more heat than your current 10/90 ratio. In CA where it never gets cold, you could run 90/10 distilled water/antifreeze + water wetter and probably be good to go.

Edit: shifting at redline will exaggerate your overheating issue. See if shifting earlier in the rev range helps keep your temps under control on track.

S14 , sorry I made a critical typo in my post about the water/coolant mix I'm running. I actually run 90% water and 10% antifreeze. I have the CSL oil cooler and OEM radiator. It sounds like I'm running the recommended setup.

I have some updated observation from a day at Streets of Willow on 10/9. The ambient temp in the afternoon was in the high 90s. With my current setup my water temp gauge stayed right in the middle, never passed middle. But my oil temp went as high as 255 by my estimation by looking at the OEM oil temp gauge. I'm aware the OEM gauge is probably not linear, nor super accurate. I looks like I still have some degree of oil temp issue on track, but no coolant temp problem.

[MPowerZ32]

You will need an electric fan to keep the car from overheating when stopped. It's fairly easy to bolt in a SPAL fan to the stock fan shroud and wire it to the aux controller.

If I understand you correctly, it sounds like you recommend removing the clutch fan and replacing it with SPAL electric fan, and keeping the aux fan deleted. Is that going to be sufficient for when the car is stopped without the aux fan?