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Im new to the BMW worldf to please dont roast me haha. I drive a 1999 bmw 528i with 309k miles. It has a misfire in cylinder 5. (just some more details about the car idk if that means anything.) Ive been driving my car for about 2 weeks and ive noticed that when Im driving that my coolant temp would go to the red for about 15-30 seconds then go back to normal. I also have the fan behind the gill doesnt work. I went to put coolant into the resivoir and when I did i noticed that there was some coolant leaking so I took off the plastic cover under the car and I noticed that when i went to add water to the coolant that it started to leak really fast and it looks to be behind the water pump. I know the gasket is fine cause nothing leaks from there and its showing no symptoms of a leaky gasket. Any help would be great!
 

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2001 BMW E39 540i Automatic Sedan, 200 k miles
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Whatever it is, fix the coolant leak asap. It is the Achille's heel of BMW cars. It is probably the water pump, coolant hoses and pipes, thermostat, expansion tank, or radiator -in this order.
 

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You’d be smart to not drive the car until you get this issue resolved-temp spiking into the red zone is not good, these inline 6 motors with long aluminum heads can be damaged severely if overheated for even 1-2 Minutes or less.


Sent from my iPhone using Bimmerfest
 

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None of us can diagnose where the leak(s) are coming from; that has to be done by you or a mechanic. The car has high miles, do you have any idea how long the various components in the cooling system have been on the car?

Many E39 owners basically refurbish the entire cooling system at 90K-125K mileage intervals - replacing:

- water pump
- thermostat and housing
- main hoses
- radiator is not uncommon either

Food for thought going forward.

The way to diagnose where the leaks are coming from is best done with a pressure tester, pressurize the cooling system when the motor is cold and identify leak points.

Good luck/Bill
 

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Thanks for the help. Everyone is so friendly. Ill be taking it into our school shop to look at it more. My mechanics teacher had a bmw and is going to help me diagnose it.
Good luck...attached article is old but some good info about the weak points of the E39. They are solid cars but the cooling systems are THE weak point on this model.

Bill
 

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