Strange noise from the engine

[Peter M]

I spent a few hours at the weekend draining/flushing and filling the cooling system with antifreeze ready for winter. Whilst I was running the engine up to temperature, I noticed a strange noise.
This is not the first time I have heard it, and I am sure that it is nothing to do with the coolant change.

The noise is like whirring gears, or a ratchet sound coming from around the front nearside of the engine. Possibly within in rocker box ? There are no blowing gasses and I even pulled of the plug cap, but his made no difference. The noise changes with engine speed. I can't pin point it, due to exhaust noise, and hot moving bits.

Am I going mad? anyone else heard this? Any explanations...
PS the engine still runs fine and power is as normal.

Thanks

Pete

[GreenV8S]

Don't know, but I would guess the noise may be coming from the timing chain? You don't want to go listening to the engine, you'll hear all sorts of alarming noises even if the engine is fine. The time to start worrying is when you can hear these noises from inside the cabin!

[Peter M]

The V6 does not have a timing chain up to the rocker box, as the cam is in the block (as far as I know).

Perhaps I should just enjoy the rumble from the pipes and not stick my head under the bonnet too much with the engine running.

[spivvy]

water pump ?

[GreenV8S]

Peter M said:

The V6 does not have a timing chain up to the rocker box

The cam is in the valley, driven off the crank (obviously). I think it's a chain drive but it could be a gear drive. Either way, it's in broadly the same sort of area as the noises you're hearing.

[steve j]

Definately not a chain drive to the camshaft, its a direct gear drive, nice pic in the bible. Check the welded seams on your manifolds and downpipes, had a similar noise on mine and the left manifold weld had gone. Clivef welded it up for me no more noise, symptoms were similar to yours.

[heyiga]

Just a suggestion, but could it be the tappetts need adjusting - unless of course you have the self adjusting type! (am not sure which S you have?)

[peter m]

I have never looked under the rocker covers, so the tappets could have a wide gap, but that would "tap" rather than a ratchet type noise. Also the noise frequency is higher than the revs.

Could be the cam drive cogs, never thought of that. It is an S2 with the 2.9 EFI engine. I will take a look in the bible.