loud noise on startup intermittently?

[prez1967]

Every now and then when I start the Expedition after its been sitting over night or for a decent amount of time (independent of weather) it'll make a loud "roar" like it has an exhaust leak...

Any ideas what this could be?

 

[stamp11127]

Could be one of many things. If possible try and post a video of it when it happens.

 

[Jeckler]

As it's starting, or a few seconds later? Mine does the few seconds later thing, make the whole truck shudder. It's the AC clutch. It only does it once a day and goes away after maybe 2 seconds. Believe it or not, I read somewhere that it's normal.

 

[soundtransmissi]

My '06 EB (165k miles) has done it for years, and does it more often than it used to. The 3 or 4 independent shops I've taken it to throughout the years to have them check it out (when I had it in the shop for something else) had no clue what it was. The last time I had the guy tell me that he thinks there might be an internal engine failure somewhere, or something. If it really is just the AC clutch, then you have made my day!