Hi guy's just wanting to find out if anyone else has the same noise as me,
i have a 95 ej20 scooby i have just fully rebuilt the engine with Mahle pistons , acl race bearings, cometic gaskets and ported and flowed heads.
My problem is i have a knocking noise from engine (i understand when idling i have the usual forged engine noise) when i accelerate the noise disappears as i let the throttle off or cruse at a constant speed the knocking comes back and does not make any difference if its hot or cold, it seems strange as it has never missed a beat and pulls well, i have done 2000m since rebuild would be good if anyone can shed some light on this thx.

 

Sounds like your bottom end has gone.
Mine was fine under acceleration or deceleration but if I held it at constand revs above 2k it knocked like hell.

 

I agree with Burbling1

Who built it?

Mine rattles when cold but only at idle, slight blip on the throttle and it goes away then comes back as it idles again, did this from the day it was first struck up after being built.

(Fully forged rebuild about 5k ago)

 

As above mate id say its the bottom end problem as mine has a slight knock when cold as the clearance is larger on forge piston's but once fully warm there is no knock especially when holding constant rev's above 2k.

 

Hi thanks for your comments, i built the engine as am a mechanic i would be suprised if bottom end is gone as i measured crank and fitted acl bearings and run in carefully still have not used much boost and warmed up not exeded 4000 rpm yet, i only rebuilt the engine as the head gasket was leaking and water had pitted the bores the old big end bearings were in good condition indicating the crank is in good order, just done a 350 mile journey and noise has not got any worse its is the same sound as is makes on idle. most big end faults i have encounterd at work sound noisey when engine is reved and is a much louder sound than mine and def didnt go away when accelerating.

 

I've heard the crank pulley can come loose or move on woodruff key,makes similar noise to knocking
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