Hard to describe - "clunk" sound on start up

Like the title says, this is very hard to describe, but I'll do my best. After my 01's been sitting over night, the first time I start it I hear/feel a "clunk", like something is engaging or gears dropping into place. It's not a very loud sound, but definitely there and it only does this after sitting for overnight or longer. After the first start of the day, it never does it again until the next time it's been sitting for a long time. I don't even have a clue where to start diagnosing this. It's definitely from the front of the truck, not the rear. Any ideas? Anything you can tell me will be helpful, I purposefully haven't used the truck today so that if any of y'all can give me an idea of what to pay attention to I can go out and start it and see what else I can tell you.

 

Sounds to me like a sticky starter solenoid.

 

That's a new one for me, can you explain? Is this a potential problem or more of an annoyance?

 

Does it take more than one turn of the key to start? I'm guessing here. Sounds are hard to diagnose without being there.
Have someone start the truck while you listen to where it comes from.

 

I'll try that when my wife gets home. Except for the noise/feel, it starts up the same every time. Only 1 turn of the key, maybe about 3 cranks, and it's going. Never struggles, never seems to have any trouble, just this unexplainable noise. It's almost like something is settling, or engaging, but I can't think of anything that would do this ONLY after sitting for hours. It takes a long time of sitting, overnight only. If I drive it to work, it doesn't happen at the end of the day, so it's got something to do with the engine being cold.

 

is the ac or defroster on?

could also be a little after fire and the exhaust muffles it so it sounds like a clunk rather than a pop.

does the noise happen after the truck is already running? like a split second after it starts up?

 

Yep, usually the AC is on, and it does happen immediately after it starts.

 

it probably the ac compressor clutch engaging, clunking when you first turn the truck on

 

Is that normal? I'd never noticed it before, any idea why it does it only when cold?

 

its normal. my 2010 does it every morning. its an electronic actuated clutch so its on off. no slipping like a manual clutch. what may happen is during the day it gets warm. overnight it cools down and water may condense (especially if its humid) and make a slight surface rust making it extra grabby in the morning hense the clunck. after the clutch engages/diengages a few times a day the rust wheres off so no clunk when you leave work. but the engine heat makes the compressor and everything else for that matter warm then over night cooler temps condesation again.... so every morning you have a clunk on startup