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Old 12-08-2012, 12:26 AM   #723
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Originally Posted by wildirish317 View Post
So, how do you diagnose a water pump, wait until you hear it scream?If you have no engine cooling problems, check for leaks and bearing play. If there is a leak, determine if it can be repaired, and if not, or excessive bearing play, replace it. What if it dies before it screams? Thermostats fail open, so you can run them to failure.If you follow your car's service booklet, during inspection 1 you read engine diagnostics, and a faulty thermostat will give you a message about how the engine is taking too long to reach operating temperature. If you are getting this message, replace the thermostat. However, you might as well replace it when replacing the water pump, since you're that deep into the engine. That's not very deep into the engine. Fan shroud and fan off, takes about 15 minutes.

Expansion tanks are notorious for cracking the length of the tank with no apparent warning. I suppose you have a strain gage attached to yours so that you will be warned of impending failure. How much did that cost?

Belts, you can see, so periodic visual inspection is okay. I just like to do it all at once and not worry about it until the next inspection interval, which is the subject of another debate.

It's a balance. Figure out the interval that you can live with, then replace the other components under the "while I'm at it, might as well...." category.
Answers included above.

You just inspect everything to make sure it's operating as it should. If it's failing, showing signs of failure, or it's near or past BMW's recommended service interval, replace it. Some parts will randomly fail, and you just replace them when they do.

BMW doesn't list "replace the entire cooling system when you feel like it" in their service booklet for a reason; you don't need to.

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