tom-r33

iTrader: (2)

my mates scoob knocks it's nuts off until the temp gets to around 50-60deg, then goes almost silent (all i can hear is injectors ticking and exhaust)
turn it off and let it cool down and the knocking is very apparent again until engine warms up.
he was told it has forged pistons and this is what the noise is. but i would expect it to be consistant on all 4 cylinders, and the frequency to be twice that of the injector ticks, but it's not. it sounds like it's coming from just 1. i know what piston slap sounds like as my old mans forged pistons slap around for abit when cold, but it's no where near as loud as my mates
he drives it so hard it's unreal and has done for about 2k and had no real issues apart from turbo oil seal going. the noise has always been there
he changed oil and filter, tried millers 10w40 and was the same and now valvoline 5w50 and no difference
any ideas?
i'm thinking it could it be a follower/lifter sticking?
cheers
tom

chocolate_o_brian

iTrader: (22)

Does he drive it hard from cold?

Jacko4130

iTrader: (3)

On cold mornings i get piston slap but the noise is more of a tap than a knock, After a few minutes it's soon gone.

TonyBurns

iTrader: (3)

What year and model car?

ShotgunUK

iTrader: (9)

Assuming that you have an STi lump with forged internals it's more likely to be a bit of piston slap. Logic seems to dictate that in order to allow them to rev higher they need to be a bit "looser" which would be more noticable when it's cold.

I used to get this on my V4 STi - even after I'd replaced the block with one from a V8 STi.

Something about the engine bay on the classic seems to amplify the noises too.

tom-r33

iTrader: (2)

NEVER!

Like I said i know what piston slap is and if i thought it was that I wouldn't be on here. I just want to ensure he doesn't do any damage as we're both pretty skint at the mo and love our cars to bits. Having to replace an engine on his a couple months after buying it would be a real kick in the teeth

V2 STI I believe

Shaks-STI

iTrader: (7)

https://www.scoobynet.com/general-te...ston-slap.html

Some info there mate.

tom-r33

iTrader: (2)

it's such a loud noise it just doesn't sound right!
on par with my merc that done a big end! but that never gets quiet

hopefully we're worrying about nothing
time will tell

cheers guys

Shaks-STI

iTrader: (7)

Try to get a video of it and post it

tom-r33

iTrader: (2)

ok. i'm going see him end of this week so will do that

Bristol98

Its not the water pump failing is it? A neighbour of mine had his let go on a celica and I thought he'd done the big ends it sounded that loud!! Don't know if it would be the same on a scoob though?