Engine overheat warning

[tam099]

I was stuck in traffic when I noticed the A/C getting warm, a few moments later a yellow warning came on telling me the engine was getting warm and to drive slower. A minute after that I get a big red warning telling me to shut off my engine because it was overheating (~255 F). Had to get it towed to the nearest BMW dealership.


I was thinking water pump or thermostat? Any other guesses? Anything else I should have them check?

2011 E93
27K miles
1 month left of new car warranty

[///M Power-Belgium]

Coolant leak ?

[vlvte90]

Same thing happened to me a few months back. Ended up being a faulty radiator fan. When you turned the engine off, could you still hear the fan running?

[nachob]

Normally, I would guess the fan motor quit but you had the AC on which forces the secondary fan motor on. It's hard to tell because if it's a cool day, the secondary fan would be enough to keep it cool in traffic but if hot, it would take both fans. An easy way to tell is if you drove up to speed and the engine temp dropped. That would let you know that a fan is not working.

The thermostat is the next most likely to quit on you but some thermostats are designed to fail in open state and some stay closed. I don't know how BMW builds theirs but it's possible it closed up causing it to not circulate through the radiator.

Water pump is the least likely because I believe the M3 uses mechanical water pumps not electrical ones like the turbo motors. Mechanical pumps are more reliable but they can also fail if the impeller breaks. Some impellers were composite and some metal. In the E46 they made plastic ones which would break. Usually an impeller can break which would prevent circulation and overheating.


If it was hot, I would say fan or fan thermo switch gave out. If it was a cool day and you run AC out of habit, then thermostat or possibly water pump.

FYI, if that ever happens to you again, turn the heater on full blast and open the windows. It can buy you a little more time since the heat exchange can help cool the coolant too.

Let us know what you find out!

[tam099]

No coolant leak or steam. It was a cool day and I was running the AC out of habit

Now that you mention it...I didn't hear any fans run when I turned off the engine. I heard some clicking when I tried to turn the engine on again after a few minutes though. Soft rhythmic clicking independent of engine speeds

[TomHudson]

Crank the heat next time.....you can use the heater core as a mini radiator..

[Helmsman]

Originally Posted by tam099

No coolant leak or steam. It was a cool day and I was running the AC out of habit

Now that you mention it...I didn't hear any fans run when I turned off the engine. I heard some clicking when I tried to turn the engine on again after a few minutes though. Soft rhythmic clicking independent of engine speeds

Tam, the fan should definitely stay on at least for a moment, when the engine is this warm.

Good luck

[digitalpersona]

Air bubble in the cooling system. You can push those out through a valve in the coolant pipes. I hear it's pretty common due to the way the system is designed.

[TTO898]

With one month left on the warranty, you should use this as an excuse to get the car in and have it checked out. They should be able to pull the history and codes from the car to see the overheat warning and will be able to diagnose it.

[Alohaaaaa]

Originally Posted by TomHudson

Crank the heat next time.....you can use the heater core as a mini radiator..

Had to do this all the time in my E30 during traffic... Middle of summer, heat blasting, sweating bullets... Fun.

[X5-User]

interesting problem...any updates OP?

[Edward]

Your service advisor will probably call you and tell you what is wrong.

You may have to call him though and leave a message because sometimes they get busy or go to lunch.

[tam099]

They are taking a look at it as we speak. I'll keep you guys updated

[TheSnail]

Serpentine belt? Not sure if the water pump and the AC compressor is on the same belt, but if so, it would make sense to me that your serpentine belt went MIA.

[BPMSport]

255F is REALLLLY hot for coolant temperature... Usually the coolant temps will lie between 180 and 210F. Heavy tracking in heat will get you to 220ish.. I would venture to say that it's a waterpump or thermostat failure, or potentially the fan.

Good luck with the fix, and great that it happened a month away from the warranty ending!

[tam099]

Since the warranty was almost up I asked the dealership to look into a few outstanding problems, mainly AC and the driver side door not unlocking from the inside.

Good news: Car was overheating because the fan failed, will be fixed with warranty. Still looking into the AC issue

Bad news: Apparently my 9 month old CPO car had some paint and or body work done. The driver side door and fender have been removed at one time or another to be repainted. I had to consent to a 340 dollar diagnostic charge if they found that the door failed because of "outside influences". That news destroyed my day. Where should I take my car to see if it's been in an accident? Carfax is clean....

[X5-User]

Originally Posted by tam099

Since the warranty was almost up I asked the dealership to look into a few outstanding problems, mainly AC and the driver side door not unlocking from the inside.

Good news: Car was overheating because the fan failed, will be fixed with warranty. Still looking into the AC issue

Bad news: Apparently my 9 month old CPO car had some paint and or body work done. The driver side door and fender have been removed at one time or another to be repainted. I had to consent to a 340 dollar diagnostic charge if they found that the door failed because of "outside influences". That news destroyed my day. Where should I take my car to see if it's been in an accident? Carfax is clean....

did you perform PPI before purchasing the car?

[maloo]

Originally Posted by tam099

Since the warranty was almost up I asked the dealership to look into a few outstanding problems, mainly AC and the driver side door not unlocking from the inside.

Good news: Car was overheating because the fan failed, will be fixed with warranty. Still looking into the AC issue

Bad news: Apparently my 9 month old CPO car had some paint and or body work done. The driver side door and fender have been removed at one time or another to be repainted. I had to consent to a 340 dollar diagnostic charge if they found that the door failed because of "outside influences". That news destroyed my day. Where should I take my car to see if it's been in an accident? Carfax is clean....

I would run an AutoCheck too. Sometimes they have different information than Carfax. Also, sometimes things eventually show up on Carfax because the information can lag.

[TrevorM3]

Originally Posted by tam099

Since the warranty was almost up I asked the dealership to look into a few outstanding problems, mainly AC and the driver side door not unlocking from the inside.

Good news: Car was overheating because the fan failed, will be fixed with warranty. Still looking into the AC issue

Bad news: Apparently my 9 month old CPO car had some paint and or body work done. The driver side door and fender have been removed at one time or another to be repainted. I had to consent to a 340 dollar diagnostic charge if they found that the door failed because of "outside influences". That news destroyed my day. Where should I take my car to see if it's been in an accident? Carfax is clean....

the car was most likely paid for out of pocket, therefore not reported to carfax.

the car was keyed, or had minor damage, on one panel or the other, causing them to paint both panels.

who said the panels were removed? body shops don't remove fenders to refinish them, so if had been "removed" it was because it had to be replaced. same thing with the door.

don't over-react over the paintwork, you didn't see it before so obviously they did a decent job.

half of bmw's, hell i'll say 90 percent of "cpo" cars out there have some sort of paintwork on them. I can guarantee that. I'll take anyone to any dealership in my area and point out every single panel that has refinish work.

[TrevorM3]

Originally Posted by Bimmer-M3

did you perform PPI before purchasing the car?

ppi's don't mean shit. i'm not sure why people are still buying into this premise.

[Beemdog]

Originally Posted by TrevorM3

ppi's don't mean shit. i'm not sure why people are still buying into this premise.

+1 . No amount of inspecting without complete disassembly of moving parts can guarantee a car is without serious defects. A PPI is good for finding things like fluid leaks or other defects only visible when the car is on a lift. If you are familiar with the specific model of car, you can do it better than a generic inspector (knowing what things should look like). If the PPI involves a paint thickness inspection, that can be a plus.