Hey guys, in the middle of a timing belt job, and I noticed something that seemed not quite right. I took one spark plug out (#4 cylinder) and I was rotating the engine via the crank to get everything to TDC. As I was rotating (the other 3 spark plugs still in) I hear air escaping from somewhere. Albeit slowly, I can still hear it. Am I crazy or is that something that isn't really supposed to happen?

 

The sound of air escaping could be from the other 3 cylinders that have compression. Compressed air is probably leaving through the exhaust valve when it opens, which is normal.

To make turning the engine by hand easier, you may want to remove all the spark plugs.

 

ok thanks for the reply. I was quick to jump to "this shouldn't be happening". Just a little paranoid i guess.

 

At really low RPM (like rotating the engine by hand) the piston rings are far from airtight. Pretty normal to hear air escaping from the combustion chamber into the crankcase.