Well, yes it's possible the guide is making the noise....but you will have to check the timing on the chain/sprockets, and make sure the tensioner is fully extended and keeping the chain tight, before putting that cover back on.......when you rotate the engine(put the crank bolt into the crankshaft and rotate the bolt with a socket setup)....watch the chain to make sure it is tight
If you don't know how to time the engine, this is a good video:
http://repairguide.autozone.com/znet...3f8024515f.gif
Basically get two drill bits(don't use the fluted ends) that fit the holes in the cams(not tight, just a little loose)......you rotate the engine until the cam holes are near the bottom...then slowly rotate the crank bolt, and push the bits through the holes in the cams into the mating holes of the rear timing cover....they should go in easily, and should not be forced...if one goes in and the other doesn't, it's not properly timed....with both bits in, look at the keyway on the crank sprocket(should be at around 12 o'clock),,,,the dot on the sprocket should line up with the dot on the block above it...if it does, the engine is timed OK......