I had the same issue with the engine in my motor home for over a year. It kept losing coolant, the low coolant light would illuminate, and I had to add more coolant after each outing.

After several "pressure tests" by Caterpillar techs found no leaks, and no drips were ever noticed, a dynomometer test revealed a leaking (read, blown) head gasket at the number 3 cylinder. The warranty claim paid for several thousand dollars of labor to replace the $150.00 head gasket. Because the problem lasted for such a long time, the number 3 piston also had to be replaced.

Don't let this issue slip past your end of warranty date as the labor to change out the head gasket on any engine is prohibitive to pay out of your own pocket.

This may or may not be the problem with your vehicle, but ask to have it checked out the next visit to your dealer's service center.

Good luck--from experience,

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DeanLinAZ
2011 X5 35i, Sport Activity
Black Sapphire/Oyster
M Sport, Tech & Conven packs
Premium sound, Side camera opt