I've got a 97 Expedition, 5.4L. I have noticed at various times that it has a noise similar to the piston slap described here. Basically, it sometimes taps for about 20 seconds or so in cold weather after sitting overnight. My wife reported hearing the noise to me once as well when she drove the vehicle. It's only done it once recently, when it got real cold here. (It's now warm again). I took it in to the dealer and reported the problem, along with a number of other things that needed doing. Even though it was cold when it went into the dealer, they didn't hear it. It's now warm again, so I'm not sure I'll hear it again until it gets cold again either.

Problem is, I've only got about 200 miles and two weeks left on the original warranty. I'm picking up the car in the a.m. Is there anything I should say to them about keeping this item "open" on the repair ticket, so that it if shows up this winter I'll be covered?

By the way, I haven't used the words "piston slap" with the dealer. I merely reported the symptoms, i.e., occasional knocking on cold start-up. The service advisor's initial response was to tell me that it could be anything, he didn't know the service history, and maybe I needed an "oil treatment." I'm more than a little P.O.'d at his this response, which could be interpreted as attempting to sell me service that Ford does not recommend. (BTW, the engine has had Mobil 1 5W30 with either a Mobil 1 or Motorcraft filter every 3000-4000 miles since new.) He then said they'd check it out, which they've done, with no problem found.

Anyone see a downside to telling them that I'm concerned that it has piston slap and that I want it covered under warranty it it appears in the future?