pcupit

I have a 2005 Subaru Impreza 2.0lt EJ20 SOHC engine.  For a while it was making a noise at around 2.5k revs we couldn't identify.  A few days ago the noise got bad the engine failed and I had to get it towed home.  On investigation I found I should have investigated earlier....   Cam belt was chewed, the cams 180 degrees out of time.  The tensioner bolt had starting coming out so the belt was moving forward, the tensioner was also chewing it's way through the cover.  The tensioner bolt (probably through vibration, or previous bad mechanic or both) was cross threaded or at least the threads of the bolt are filled with aluminium from the block...

My question is, is it possible to put in a helicoil without removing the engine from the vehicle, my thought it not since that bolt would probably need to be very accurately in parallel with all the other shafts of the pulleys etc.

Of course RHS valves are probably bent... So it's all bad..

Any ideas appreciated. Images:  20191221_170149.jpg   310.2KB   1 downloads  20191221_172858.jpg   241.69KB   1 downloads

Thanks.