Hi there
So I am not sure if this noise has always been present or is new but in short the best way I can describe it is as follows:
Car engine runs and idles fine, sounds fine like a sewing machine which is how an M20B25 should sound, valve lash set at 0.010" (0.25mm) and I have double and triple checked this. Cas has had major service so every filter and fluid in car is fresh.
At 3500-4500rpm under heavy or full throttle I get what sounds like top-end tapping/ticking/rattle noise, it increased with RPM, so my thoughts were valve adjustment or the dreaded bottom end knock (rod bearings) but if I accelerate gently through I get no noise, if I accelerate hard past 5000rpm I get no noise, it is only 3500-4500rpm on medium/heavy to full throttle, the noise does seem louder the harder I apply the throttle but then quietens off as 5000rpm approaches and confirmed by driving through a tunnel, no noise.
Very quick video but phone does a bad job of picking the noise up, play it on loop and you should hear it:
Would a bad rod bearing(s) stop making the noise under light throttle I thought if bottom end was in question then it would not at all RPM and irrelevant of throttle load?
Could it possibly be pinking/detonating and hence only happens under heavy throttle?
Maybe a really loud injector clicking?
Or the valve lash need setting tighter maybe?
Any other ideas?
So I am not sure if this noise has always been present or is new but in short the best way I can describe it is as follows:
Car engine runs and idles fine, sounds fine like a sewing machine which is how an M20B25 should sound, valve lash set at 0.010" (0.25mm) and I have double and triple checked this. Cas has had major service so every filter and fluid in car is fresh.
At 3500-4500rpm under heavy or full throttle I get what sounds like top-end tapping/ticking/rattle noise, it increased with RPM, so my thoughts were valve adjustment or the dreaded bottom end knock (rod bearings) but if I accelerate gently through I get no noise, if I accelerate hard past 5000rpm I get no noise, it is only 3500-4500rpm on medium/heavy to full throttle, the noise does seem louder the harder I apply the throttle but then quietens off as 5000rpm approaches and confirmed by driving through a tunnel, no noise.
Very quick video but phone does a bad job of picking the noise up, play it on loop and you should hear it:
Would a bad rod bearing(s) stop making the noise under light throttle I thought if bottom end was in question then it would not at all RPM and irrelevant of throttle load?
Could it possibly be pinking/detonating and hence only happens under heavy throttle?
Maybe a really loud injector clicking?
Or the valve lash need setting tighter maybe?
Any other ideas?
