Hi,
I have a 2000 Forester S with 90K miles on it. If I have been driving the car for ~15 minutes or more, then I stop to get gas or something similar, when I start the car again a few minutes later there is one loud knock/klunk. After the one knock there are no more bad sounds, just the normal hum of the engine. The knock is strong enough that I can feel it in my hands on the steering wheel when the car starts.
Any idea what could be causing this?