The belly pans serve as noise capsules and streamliners for the floor, The cooling problem is usually a problem with the radiator/condenser/fan. Bugs/leaves in the condenser fan shroud bottom will effectively cover 30% of the condenser and hence radiator. If the fan clutch is not working like it should, the engine wont cool down.

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2012 BMW X5 (Beef + Granite suspension model)

1995 E300D - The original humming machine (consumed by Flood 2017)
2000 E320 - The evolution (consumed by flood 2017)