My Mondeo did this, like a diesel at Idle and rattles at faster revs. It
turned out to be the cam belt idler/tension pulley had broken up, so the cam
belt goes slack and jumped a tooth. I got away without any other damage, do
not run your engine till you know what it is.


"Arfa Daily" wrote in message
...
Focus 1.8 Ghia Estate. 2000. Tad over 100k miles. Last night, it suddenly
started making a nasty noise from the engine, so bad that even my daughter
commented on it, and it's got to be noticeable for her to hear anything
wrong with a car engine ...

When it's idling, it sounds like a diesel. That's honestly the best way I
can describe it. As the revs build, it becomes more of a growl, until at
2k, it smooths out like a switch has been thrown. I've had a listen this
morning with the bonnet up, and it sounds as though its coming from around
the front side of the engine, and doesn't sound as though it's anything to
do with the exahaust system. My tame mechanic friend, who hasn't actually
heard it yet, suggests a leaking injector seat can cause this sort of
problem, allowing excess fuel into a cylinder at low revs, causing random
detonations. This sounds a bit fanciful to me. Anyone got similar
experiences to share ? Anything common on this engine ?

Thing is, it sounds worryingly like my little Fester did, when it knocked
an end out, and which ultimately led to my scrapping the car, although
that may have been slightly different in that the worst of the noise was
when you were on a light throttle at any revs, whereas this definitely
seems to go away as you pass 2k revs.

Any thoughts from the (far better qualified than me) 'usual suspects',
much appreciated.

d:-\

Arfa