Hi, I'm new to this, I have a 2010 Subaru Impreza 2.5i Premium. Well it's been sitting  for almost a year bc the number one cylinder side sparkplug got loose and shot out messing up the threads so bad that the spark plug wont tighten but I fix that put the head back on and now I have a knocking sound coming from that side and it never knocked before that, it's a new motor only 2years old. I'm lost and need help. 

Edited December 4, 20196 yr by Micheal

Michael,

No knocking before you fit the helicoil (assume that you went that route?), but after reassembly you now have a knock.

What comes to mind is that either the helicoil is too long (sticking down into the combustion chamber and hitting the piston), or the helicoil allows the spark plug too far down to do the same thing, or you have somehow got the valve train out of timing and its hitting the piston, or you've dropped something down into one of the cylinders during reassembly.

Let a good mechanic  evaluate the issue first, but I'd be pulling the head again.

Yeah that's what i used and it's not sticking down through too far and the sparkplug is sticking down through the same as the other sparkplug. I'm going to check the timing and and drain the year old gas in it and put fresh gas in it. Thank you for your respond. 

It was out of time, the knocking went away. Thank you again. 

Thanks for letting us know that the fix was

You're welcome.