I might be wrong but I thing the life of the valley pan and the coolant pipes O-rings in the back of the engine (M62) can have a longer life if the coolant circulates through the engine after it's shut off.

Last year I had the engine out of the car and I replaced all the gaskets, O-rings... everything. When I did that I found that the two O-rings on the coolant pipes at the back of the engine were squared and harder rubber than the front or a new set. The interesting part was that these O-rings have been replaced a year and a half before that when I did the valley pan. There was no coolant leak from these O-rings last year but I assumed it was coming.

This year I had the tranny out for a rebuilt and I found a coolant leak which it was coming from one of the O-rings. I don't remember if the big or the small one but both looked square and hard. The front o-rings looked good and soft.

I replaced them again and I suspect the cause of this is the heat that builds up after the engine shuts off or it can very well be because there is less ventilation during normal operation behind the engine.

Now, one solution I am thinking of is to have the auxiliary water pump running a few minutes after the engine shuts off. To accomplish this you can use the REST button or code the car to turn that option on if that's an option with NCS Expert. I am not sure for controllers that have MAX instead of REST.

I will also try civdiv solution to lower the engine temperature which will also help for this problem.

Any thoughts?

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4.8is 2004 imola red
4.8is 2005 Black on Black - DINAN/2 sold
4.4 2004 X5
2003 330xi
2008 328xi - sold
4.4 2000 X5 - sold