Overheating on fwy with AC on during hot weather

[Johnvu]

I had this same issue on hot Houston summer days. I ended up getting Mishimoto electric fan kit and it solved all of my overheating issues. My water temp gauge never goes beyond the center now.

[cozmo kraemer]

What I noticed today after driving some more is while driving up hill at a constant 75mph on the fwy, both the engine temp and water temp rises as well. I had to ease off the throttle and slowly go up hill at 65 to get the temps back to normal. At this point it seems like my radiator cant cool my engine sufficiently. Should I replace it with a genuine OEM radiator which I usually buy from FCP or are there any brands that will perform better than stock?

Most people on here will recommend stock. It is sufficient, even for track use. There are not very many aftermarket options that improve upon it.

[yhp2009]

I had this same issue on hot Houston summer days. I ended up getting Mishimoto electric fan kit and it solved all of my overheating issues. My water temp gauge never goes beyond the center now.

So a single mishimoto fan had a better result than the 2 fans(engine fan + aux fan) that come stock?

[Johnvu]

So a single mishimoto fan had a better result than the 2 fans(engine fan + aux fan) that come stock?

I replaced the mechanical fan with the mishimoto and kept the oem AUX fan. This combination has kept my temps perfect.

[Cisco Kidd]

I replaced the mechanical fan with the mishimoto and kept the oem AUX fan. This combination has kept my temps perfect.

I have the same setup mine moves a bit still if im burning down the freeway and temps are 100+ in the summer but as stated in the manual its normal for our cars to jump a bit. ive had the setup maybe 4-5 years now with no real issues aside from adjusting the fan control here and there cause they tend to run for longer than need be.

[yhp2009]

I replaced the mechanical fan with the mishimoto and kept the oem AUX fan. This combination has kept my temps perfect.

That sounds like a better setup. Is it a relatively safe/simple fix to get two electric fans working simultaneously?

[M3steve]

I’m going to jump in here (rather than start another thread) because my issue is nearly identical to OP.

I had a similar overheating issue last summer not long after purchasing the car, and it threw a low coolant temp code (thermostat). Over the winter I did a cooling overhaul... thermostat, water pump, flush, and I ditched the clutch driven fan and went with the Mishimoto (like Johnvu above). I did NOT do a new radiator.

Last weekend I went for a drive in the mountains, ambient temp around 80, A/C on. About 5 min into an uphill climb at about 60mph (~4K rpm), I started overheating. I hit 3/4 water temp and pulled over to let it cool down.

Radiator replacement is about the only thing I can figure. My coolant mix is 50/50. I appreciate any input.

[old///MFanatic]

Before throwing expensive parts and time at this you really should replace the lower radiator hose temp sensor (for pusher fan) and the other temp sensor (coolant/engine) by the t-stat.

[0-60motorsports]

Before throwing expensive parts and time at this you really should replace the lower radiator hose temp sensor (for pusher fan) and the other temp sensor (coolant/engine) by the t-stat.

Just ordered both of these since they are so cheap and my thermostat one has not been changed since the car was built

[Johnvu]

That sounds like a better setup. Is it a relatively safe/simple fix to get two electric fans working simultaneously?

Yes, pretty easy to do. The fans run independently on separate electrical systems. The Mishimoto kit includes a fan controller that uses a radiator probe or npt sensor to read coolant temps. You adjust the activation temp by rotating the knob on the fan controller. All in all a pretty easy install.

Make sure you wire up the fans to pull and not push. I had them wired correctly but then I later installed a waterproof electrical connector, making it easier to disconnect and remove the fan. Well, the connectors can install upside down, reversing the fan to push. Needless to say, nothing cooled down and the fan ran for 20+ minutes after shut off because it was shooting hot air from the engine into the radiator lol.

[yhp2009]

Yes, pretty easy to do. The fans run independently on separate electrical systems. The Mishimoto kit includes a fan controller that uses a radiator probe or npt sensor to read coolant temps. You adjust the activation temp by rotating the knob on the fan controller. All in all a pretty easy install.

Make sure you wire up the fans to pull and not push. I had them wired correctly but then I later installed a waterproof electrical connector, making it easier to disconnect and remove the fan. Well, the connectors can install upside down, reversing the fan to push. Needless to say, nothing cooled down and the fan ran for 20+ minutes after shut off because it was shooting hot air from the engine into the radiator lol.

Woah, that would have been a head scratcher. Thanks for the tips

[0-60motorsports]

Ok today's update is that after monitoring AC pressure during warm up and overheating the pressure goes UP. So first thing to be changed and easiest will be the drier and Expansion valve (later). I will be picking up the drier today. Updates to come by Saturday or Sunday.

[Elgonz13]

Ok today's update is that after monitoring AC pressure during warm up and overheating the pressure goes UP. So first thing to be changed and easiest will be the drier and Expansion valve (later). I will be picking up the drier today. Updates to come by Saturday or Sunday.

Any solution?

[0-60motorsports]

Any solution?

Fuck NO same shit different day. As the temps go up above 38c the M3 starts hitting 98c water temps which is 3/4 on the gauge. Turn the AC compressor off and temps drop off or if I start driving and stay around the 60mph mark they come back down the normal half or 93c approx. AUX fan is working happily and so is the clutch fan.

Everything is new so I don't know why I can't the demon out of the cooling system of this car. Compassion and leak down came back good.


Noticed that my front radiator cowling disintegrated so got a new one.

[Cronenberged]

MODINE no longer produces our radiator. BMW uses some company from Germany that has one factory in Germany, three 3 others in China. Right now it's unknown where our OE radiator is coming from.