This most likely pertains to daily drivers. Had thermostat replaced (that's going to be another thread). Tech thought he dropped a bolt under the cover by the power brake unit. I took the cover off and found the plastic tub that houses the Power Brake hardware was almost full of water. There is a rubber grommet on the engine side of the tub which would keep it from filling to the top. My concern was the number of electrical connectors that were lower then the grommet. Another inch of water and all kinds of stuff would have shorted out. I don't have a shop-vac so I used my Little Green Clean Machine to pump out most of the water. The rest I soaked up with a towel. Sure enough a leaf was covering the drain hole. Another thing I will checking from time to time. Jack