how common is it that it actually does damage and not drop down into the pan?

 

I've never heard of it causing anything besides just breaking and falling. but im sure there are freak occurances where it has like pieces that get between the chain and gears and snaps the chain or something.

 

Just remove both guides so you won't have to find out! And I've heard of a few times where it has caused quite a bit of damage.

 

The chances depends on the condition of the guide itself. If its completly cracked and is only hanging by a thin piece of metal, chances are its going to fall down and eventually some other moving part will pick it up and try to eat it. There are horror stories about this online. Some motors survive it, some dont.
I removed my old KA when i had to replace the valve and spark plug gasket. took me only 1 min to take them out. When i looked at the guide, which is only a piece of steel angle, there was a nice long crack underneath it.

Just unbolt the valve cover, and take a #10 socket wrench and remove the two bolts.
I called up nissan to see if they have a replacement for it, the parts lady said that Nissan discontinued it.
It was simply another mistake that nissan made in the past.
The lower guide is harder to remove, so i didnt bother touching it since the upper has a better chance to break off.

 

k, thanks. thing is it`s already broke and in the timing cover somewhere. i`ll tow it.

 

My friend broke his and it got cought on the chain. It destroyed the engine inside. It left a nice hole on the block too!

 

Hey, sounds like what happened to me!