2007 Focus ST 225 - weird engine grumble

[gipized81]

I appreciate this is a long shot, but if any of you could throw ideas at this I’d be grateful.

Basically, at 1200rpm there’s a growl/resonance coming from the cam-belt side of the engine.

https://youtu.be/8d9dyaR3HYw

It’s had a new oil pump, water pump, cam belt cover, cam belt and tensioners. There are no error codes, no warning lights and it goes like it should. There’s no a smoke or anything like that.

To me it sounds like something plastic vibrating at the right revs. I wondered if any of you had heard the same thing..? It’s driving us mad not knowing what it is!

[sherman]

Tappets?

[gipized81]

It’s not coming from the engine itself. More towards the far end on the cam-belt side.

The actual engine sounds sweet as a nut.

[Novexx]

From memory the aux belt runs outside the cambelt & has it's own tensioner - has this been replaced?

Not the same engine, but Mondeo's of the same age used a similar aux belt tensioner & it was well know for going weak & allowing the belt to flap around too much creating a random noise that would come / go at certain rev ranges. If this is going on, the vibration / flap / slap in the belt can be seen when the noise occurs

[sherman]

Is there undertrays?
Is one lose or has something dropped on and got stuck on the tray.

[mikeone]

That sounds similar to mine (ive had two since 2015, still on my second) when the water pumps go off, other than that ive not heard one quite like that.

Otherwise youll need to get a mechanics stethescope and poke around down there when the engine is spinning...