Strange Noise On Overrun

[Gaz 29]

CF1 2.0 TS 16v in a 145 Cloverleaf

 

Engine is well maintained, regular oil checks/top ups, new plugs every year. Equipped with half decent panel filter, Alfatune exhaust system and Alfatune remap running 170bhp

 

When the engine has been warmed up, it pulls very strongly but when slowing down or when the revs are falling from mid range to tickover, it makes a strange rattly/ticky/grinding noise around the 2500-2000rpm mark. Doesn't do it under power or holding the revs steady, only when the revs are falling. It is due a full belt change soon but this noise sounds like its coming from the passenger side, or certainly to the left of the drivers side, could be a central noise.

 

It is definitely engine related, nothing to do with gearbox (that i know of) as it does it when either driving along, in any gear, or when stood still.

 

Any thoughts guys? If it needs a new clutch and/or flywheel, sod it. Its getting ripped out and replaced with a 20v turbo from a Fiat Coupe!

[Smaky 73]

Is this a daily use car?

[Gaz 29]

Varies. It can go weeks without being used but i have done 26k in 2.5 years

 

Or if you mean its had it and needs engine surgery then no its not a daily user

[Smaky 73]

Try it with the balance belt off.

[Gaz 29]

Will do. Its only started making the noise recently if that makes any difference?

 

If its that, would that be a case of just re-timing it or a new balance shaft?

[Smaky 73]

If that silences it then just leave the belt off as you probably have a failing bearing shell and these require removal of the engine to rectify, but we haven't confirmed anything so don't panic yet.

[Gaz 29]

Tidy. Cheers Alex