Hi, Ive been trying to check the TDC on my VQ35DE engine but there are two marks on the timing case and I dont know which is the right one. One is the typical grooved line and the other is a timing pin.
According to the factory service manual I have to align the grooved line with the 0 ° in the pulley but when I did that the piston isnt in the TDC, maybe 1/4" before TDC and the camshaft are not aligned as shown by the FSM (in compression) is closed but not at the top. On the other hand when I turned the pulley to the PIN, the cam were aligned and the piston was in te top of his stroke. .

So I need to clarify what is the right mark and why the top of the piston isnt in the grooved line.

This engine has never been disassembled so I dont think that it is a wrong timing chain installation or chain stretched

 

Interference motor. If you weren't timed, you'd be striking valves.

But to answer your questions, (1) yes, that is the correct mark, and (2) I have no idea.

I've had my chain off, and I wouldn't recommend going there unless you're confident with your skills. Timing this motor with cams on can be stressful if you don't know what you're doing. The cams are spring loaded without the main chain and will skip if you're not careful, throwing off your chain position and causing valve strikes. Then you get to pull all camshafts, VTC components, chains, blah blah blah and start from scratch. And hope you didn't bend a stem.