John Durose

My 08 WRX STi UK has only done 30k miles. I'm not an engine abuser and I have good slippy stuff put in. However, on cold start up after work one day, there was a momentary knock. Initially, I thought it was just one of those things, but as I drove home, I could hear a slight knock when I released the accelerator. This got worse as the engine warmed up, becoming evident at lowering rpm, but only when I backed off and dipped the clutch, (as in changing gear). So I could drive without knocking as long as I didn't change gear.
After a few miles, the engine light came on, cruise and Sport lights flashed and it went into limp mode.
A friend with a code reader said it's showing a cam to be out of phase/time and suggested it could be a AVCS solenoid failure, but he knows little about new age subarus and said I needed to get it to a specialist.
I got it to someone who has worked on subarus for me in the past, but I now know he's not done much on new age models. He and his colleague are strongly suggesting it's big end failure and the cam timing fault could be linked to that.
I'm a bit loathed to sanction engine removal and strip based on "sounds like", but I don't know what else to do. In any event, I'm told that if it is big ends, then it would probably be better to get a replacement long engine rather than rebuild mine.
From what I can tell, a decent used engine will be circa £2000 and then there's a new oil pump, new oil cooler, fitting, etc, so I'd be looking at at least £3000.
Is a rebuild such a problematic option that most technicians don't want to do it?

Any comments on the above would be welcome.