Prius made a loud clancking noise, came from ICE

Hello

2010 with 61000 kilometers.

Yesterday morning it was a rainy and damp weather around 3-4 degress celcius when I started my Prius. Usually I start it up, get out and have a cigarette or something before driving so that the ICE has a minute or two to warm up. Immediately after the ICE fired up I heard a very loud clanking and vibrating sound. I immediately shut the car down, checked all fluid levels and read the codes. No codes, no warning lights. Fired it up again, same thing. This time I opened the hood and went to see what's going on. The ICE made this noise and vibrated like hell. After a few second though the clancking and vibrating slowly went away and it started to sound normal again. Phew!

Scared the living crap out of me! This hasn't happen before or since. I had like 2-3 40km drive cycles after that on the same day with no problems. The day before I had to move the car just a bit, and when doing that the ICE came on just before I turned the car off.

No codes, no warning lights. First thing that comes to mind was a misfire that vibrated the engine like crazy, maybe due to the damp weather effecting spark plugs or a flooded cylinder that was due to the only a few seconds of engine running the day before.

I'm going to have the transmission oil changed soon, so I'm going to tell the dealer about this and ask if they could use a dealer level scan tool to check if anything pops up. Before that, I wanted to ask you what do you think? The sound was really scary to my ears, almost like it ran with only one cylinder accompanied with a metal clanck sound, maybe due to the engine hitting something. Thoughts?

 

Fired it up just now this morning, no problems. Hmm...

 

OK, thanks for the info!