I've noticed a wet spot under my car. directly under the reservoir tank. i couldn't tell if it came from the hoses or the tank. so i filled the tank with some water and drove around the block a few times. pulled back into the driveway and started to hear a dripping noise hitting the cardboard i put under the car. the drip certainly comes from just under the expansion tank because i can see stains dripping down. If i bring the car to my mechanic can he test the cooling system to be sure it is directly a leak coming from the tank?