My '79 300D clatters and clanks pretty loudly in the a.m. when it is cold. It stays that way until it hits operating temp.at about 100-150 degrees. I don't hear it any more, even after sitting for a few hours as long as it's sufficiently warm. Someone mentioned the timing chain, but the tech who did my minor "tune-up" told me not to worry about the T-chain until I hit 100,000...I'm at 90,000 now. (He didn't hear the clank as the car was warm). Should I be concerned?