Why is there an engine knock after removing the bolts from the engine head?

[notACoolKid]

Hi all,

I’m new to these forums and to cars generally, so I don’t really know what I’m doing all that much but I’m trying to learn. Today I wanted to check the timing chain on my Yaris as some people were telling me it was coming loose, so I tried. I unbolted the engine head but for some reason it wouldn’t come off no matter how hard I tried. So after that I bolted everything back on and when I later turned my car on I now had a knocking noise.

If anybody could explain why this could have happened I would appreciate the feedback, I’m so lost as to what it could be from just undoing a few screws.

[remcafee]

i admire you trying to learn and work on your own car, however you need to have some experience with mechanical equipment if you are going to tackle timing stuff, it is near impossible to telediagnose a problem for you and most shops would run away if you took it to them and told them you messed with it and now shits not running right, so you said you loosened the head? as in the cylinder head bolts that are that special 8mm bihexagonal socket?

[WeeYari]

Oh man. Sounds like what you were attempting to undertake is like saying "Hey, I can cut paper with scissors so I'm good to go attempting open heart surgery."
For help here at this point, you need to photograph everything that you touched. Practically every bolt on an engine is subject to specific loosening/tightening sequences and precise torque specifications.