Overheating on fwy with AC on during hot weather

[0-60motorsports]

My Alternator (specifically my voltage regulator) were going out and I noticed my water temps starting to move off of the center line! This could be it

I will keep everyone updated as soon as fcp fix an issue with shipping system so I can order the alternator

[AWE46M3]

All I can tell you is I have my car and another M3 next to each other in the shop and mines missing lol

Also an update on the overheating, seems to be an electrical power issue. When the car is overheating at 3/4 water temps and we connect another running car to my M3 to boost electrical output temp drops in 2 mins! I'm thinking alternator is not working at a 100% under load etc. so I'm going to order an X5 140amp alternator or a 150 Amp Z4M alternator.

My Alternator (specifically my voltage regulator) were going out and I noticed my water temps starting to move off of the center line! This could be it

[0-60motorsports]

Yea see, what on earth is that? I'll have to go out and look at my car, but that piece is not looking familiar to me even after having had the whole front clip off.

All I can tell you is I have my car and another M3 next to each other in the shop and mines missing lol

Also an update on the overheating, seems to be an electrical power issue. When the car is overheating at 3/4 water temps and we connect another running car to my M3 to boost electrical output temp drops in 2 mins! I'm thinking alternator is not working at a 100% under load etc. so I'm going to order an X5 140amp alternator or a 150 Amp Z4M alternator.

[Pklauser]

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

Yea see, what on earth is that? I'll have to go out and look at my car, but that piece is not looking familiar to me even after having had the whole front clip off.

[0-60motorsports]

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.

Replaced with a brand new one last year. And the sensor in the lower radiator hose too.

The heater core you mean the one under the dash? Brand new evaporator and heater core installed last year too. No difference whatsoever.

[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.

[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/

[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.

[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.

[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.

[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.

[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]

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.

[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 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.