Overheating on fwy with AC on during hot weather

[Slideways]

Everything you can think off. Original radiator was returned back as installing the new one didn't change a thing. I have Bimmerworld oil cooler which works perfectly. Condenser replaced too.

Water pump etc all OE BMW brand new.

I was going to suggest the condenser lol. Unless one of the parts is defective, it could be the coolant passages in the block or head are partially blocked. This can happen due to age or the wrong coolant being used. There is a video on a rebuild where the guy is scraping chunks of debris out of the coolant passages around the head gasket area.

I drove an M3 in 100-110F with the original everything other than t-stat and water pump and it did the same thing with the A/C on.

[0-60motorsports]

What have you replaced so far?

Everything you can think off. Original radiator was returned back as installing the new one didn't change a thing. I have Bimmerworld oil cooler which works perfectly. Condenser replaced too.

Water pump etc all OE BMW brand new.

[Slideways]

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.

What have you replaced so far?

[0-60motorsports]

The thermostat housing has a seal where the housing meets the thermostat. It's built into the actual housing and not serviceable. Was your thermostat pretty loose when you fitted it?

Could be having some water leak past that joint. Tho, I'm not sure why that would cause over heating? Anyway, just a thought…

hope you get it resolved. That's a bummer!

No it should be fine. I'll have the tech look at it or I'll do it myself if I get a chance.

[tlow98]

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.

The thermostat housing has a seal where the housing meets the thermostat. It’s built into the actual housing and not serviceable. Was your thermostat pretty loose when you fitted it?

Could be having some water leak past that joint. Tho, I’m not sure why that would cause over heating? Anyway, just a thought…

hope you get it resolved. That’s a bummer!

[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.

[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.

[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]

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.

[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

[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.

[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

[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.

[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.

[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?