330S seems noisier or am I paranoid?
 

Hopefully I am being paranoid but my 330S seems to be a bit noisier in the engine department. There seems to be a clicking sound on idle particularly noticeable on cold start but then less noticeable after. I can't really detect it with revs. Any suggestions what this could be? I have had a blob wrx with a bottom end failure in the past and I could hear that in the car. This you don't really notice anything in the car, admittedly the hatch is better soundproofed. It still starts and appears to drives faultlessly and no warning lights or other symtoms.

I bought the car with a 5,000 mile fresh build with Mahle 2618 Pistons, ACL bearings and a new crank and steel rods. The car has done a further very easy 5,000 miles mostly with my wife on the school run and a little by me (as I work abroad most of the time). Although I have never driven it properly as I always have the wife or little one in the car. The average mpg has never dropped below 28.2 to give you an idea of the use. It's had 2 oil changes in my ownership.

My local Subaru dealer (Abergavenny) can't look at it before Christmas and I would just like to know asap as I need to use it to visit family over the Christmas period. Is there any fool proof way to rule out the bottom end? It sounds more top end to my limited experience. Is there any one around the Hereford area who could lend me their experienced ear?

I have not had much luck with the Subarus I have owned despite treating them like baby's hence I am particularly worried now.

Any advice would be gratefully received? Thanks

Maybe this is normal? Would you expect a forged build to get a bit noisier as it loosen up or is it a sign of problems?

with those pistons I'd expect a degree of noise as they require a little more running clearances.

Mine was pretty quiet when first built. well to be fair still is but slightly noisier in the winter months but has covered 16000 miles of hard road use.

Thanks Rob, I have only noticed it in the last week or so. Maybe it is a winter thing but why is that?

If I change the oil and there isn't metal particles present then can I rule out the bottom end or not necessarily?

Somthing to do with forge pistons being loose in the cylinders when cold (winter) as they heat up the expand for a tight fit. A problem less comman with cast or so ive read

Piston slap.

I'm no expert but I don't think it's piston slap. I think it could be the cam belt tensioner on the way out (at least I hope that's all it is). I will get it booked in asap. Assuming it is the tensioner can I use the car for short journeys in the mean time or is that asking for trouble? I don't have access to another car at the moment so it will mean hiring one over the Christmas period which isn't going to be cheap!

By the description its piston slap

Well it was the cambelt tensioner! Got it changed and much quieter now!

Result ....

Yes I was worried for a bit. Still a hefty bill but far better than a rebuild!

The later style cambelt tensioners are not as robust as the earlier ones, seen a few fail on race engines.