See that little slug pointed to in the photo? That goes inside the spring, down at the base of the spring where the spring seats inside the tensioner block, right?

There's a dimple in one end of the slug. Anyone know which way this dimple needs to face? Does it matter?

 

Does the detent fit over the end of the cone-shaped protrusion that is centered inside the piston bore of the valve body, where the oil comes out (there's also a little ball check asembly pushed on over that protrusion, FYI)? I just looked at my old one, but don't have the slug piece and may have lost it when the parts went into the chain case during removal (I was able to retrieve the spring and piston tho).

 

I think the dimple end goes towards the rear of the tensioner. I could be wrong here though ... I would check in the tensioner itself and see if you see a detent. Why is apart, you should have locked it in place upon removal.

Also, I see two tensioners, any special reason?

 

The same thing happened to me. I took apart the old one and new one for a look and did not pay attention to the orientation of the little plastic slug. Anyway, I put the dimple end facing the tensioner body. It has been almost a year now, no problem. Note: If you are having knocking problem in the morning, might as well add the metal gasket. I did not initially and had to do the job again. You can get the metal gasket from the dealer. It is one of those Nissan TSB.