Hey guys, I just bought a 2003 350z with 135k miles on it. Right after I bought it the Service Engine Soon light came on, I had it checked out and it turned out to be a misfire on plug #1. So today while waiting to put new plugs in it I decide to seafoam the car via the vacuum line. I put about 1/3 in the line very slowly and 1/3 in the gas tank. Soon after I began to hear a knock while the car was in neutral with the clutch out, however if I push the clutch in the knock/ticking noise goes away. Any idea what could be causing this? Could it just be the spark plugs or maybe the input shaft bearing? Any input is very appreciated.

 

Track down exactly where the ticking is coming from. If tranny, it's probably throw out bearing. Mine makes the same tick when it neutral after it's been driven for more than 10 minutes.

 

If it's gone with the clutch in it's probably just the gear lash in the transmission acting 'normal'. If you have a misfire it's going to be worse.

 

Throwout bearing.. Mine does the same when first started.
Should go away once the car is driven...

 

Throw out bearing is very common on the z. I personally have had that sound since i bought the car with 30K miles now at 45K.

I think it's not going to hurt the clutch or tranny but be very annoying.

 

I bet it's the throwout. Mine was awful, and when you turn the car off with the clutch it sounds like you're murdering a duck. But I just upgraded to JWT clutch and flywheel and it's now gone.