Overheating on fwy with AC on during hot weather

[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!

[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.

[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]

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]

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]

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.

Well the cars fairly low miles at 80k kms. I doubt any of the passages are blocked, only coolant ever used in the car is BMW OE coolant with water wetter sometimes.

All the other parts are good and I checked the water pump today and no noise plus it probably has 1-2k kms on it tops lol. OE BMW.

[sapote]

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'm sure the same M3s were sold in Bahrain and similar climate countries when they were new, and so they didn't have these problem when new driving in hot weather. If radiator and condenser are new clean OEM then the issue is either not enough coolant flow or air flow.

[0-60motorsports]

I'm sure the same M3s were sold in Bahrain and similar climate countries when they were new, and so they didn't have these problem when new driving in hot weather. If radiator and condenser are new clean OEM then the issue is either not enough coolant flow or air flow.

One theory is that that the air dam (number 2) in the front needs to be changed and there is a part missing on top of the radiator as well that must have fallen out at some point…



Number 1 in the above diagram.

We want to change those first and then test the car and see how it behaves.

[tlow98]

One theory is that that the air dam (number 2) in the front needs to be changed and there is a part missing on top of the radiator as well that must have fallen out at some point…



Number 1 in the above diagram.

We want to change those first and then test the car and see how it behaves.

definitely replace the missing radiator shroud. That’s a huge part of the efficiency of the system.

[0-60motorsports]

definitely replace the missing radiator shroud. That's a huge part of the efficiency of the system.

Yeah got a brand new one sitting here ready to be installed. Will report back once it's done.

[Pklauser]

Do the temps stop at 98c, 3/4 on the gauge? I was under the impression that, while warm, that's a totally valid place for temps to be.

Edit: Also what is Home in that diagram? Would love to see a pic of where that is on-car.

Edit 2: uhh my "number 1" got replaced with a link, weird.

[sapote]

“Edit: Also what is Home in that diagram? Would love to see a pic of where that is on-car.”

Item 1 is the metal bar cross the top, I think.

[0-60motorsports]

“Edit: Also what is Home in that diagram? Would love to see a pic of where that is on-car.”

Item 1 is the metal bar cross the top, I think.

Number one is https://www.ecstuning.com/b-genuine-...p/51717893229/. Not the metal radiator support.

[0-60motorsports]

Do the temps stop at 98c, 3/4 on the gauge? I was under the impression that, while warm, that's a totally valid place for temps to be.

Edit: Also what is Home in that diagram? Would love to see a pic of where that is on-car.

Edit 2: uhh my "number 1" got replaced with a link, weird.

So far stopped at 98 as i didnt want to piss it off more so it blows its top LOL. Coming from a region were the normal temps are 125f with high humidity (ambient temps are almost this or higher up to 140f as i used be standing next to the pirelli guys at the Bahrain F1 in the pitlane when they were measuring). I couldn't care less when people tell me its just as hot in some states in America, ITS NOT.

So after you read the above, im telling you and everyone that when its 125f out and im in the m3 between 1200 and 1400 hours the water temp never used to go above half or a max of 92 in traffic or on the highway. But those were the good days and that was 4-5 years ago! bahhaahhaaha. I think im coming close to really giving up and just using the M3 when temps are below 40c here. FML.

https://www.ecstuning.com/b-genuine-bmw-parts/cover-top/51717893229/

[Slideways]

When did you replace the temp sensor under the manifold? I had a genuine BMW one go bad after 20k miles and 5 years. No codes, but the temp gauge would randomly fall to the first dot or below.

I believe the only other item left in the coolant circuit is the heater core.