Dave Bullock

I don't know if what I'm hearing is detonation or whatever the tech term is but my MY99 seems to have a slight knocking noise at idle. It isn't there all the time but is very noticible at times.
I'm running mainly 95 RON UL but I have put through a tank full of 98 RON but I could still hear it knocking.

Stef

Mine knocks too Dave. I think they all do to a certain extent.

Stef.

MorayMackenzie

Mine has a special sensor to listen for the onset of the knocking and prevent it!

MorayMackenzie

Seriously though, it may be the valve lifters, which can make tapping noises until the engine warms up. Is the noise on idleing a cold engine?

Moray

Dave Bullock

Nope cold or warm.
I've got to take it back to the dealers for something else so I'll get it checked out then.

ChrisL

Had a 'knocking' noise on my car back in April this year (UK MY96) and pondered on the cam/lifters clearance idea, oil pressure, etc.

Took the car in to my dealer who diagnosed piston slap. One month later I had a new MY99 short-motor installed FOC under warranty.

Not saying it's this, but the noise never went away 100% and was very obvious within the first 10 mins of driving.

Still, "Knocking" can be a zillion things but best get it checked out.

AlexM

Hi,

My MY98 sounds like it has piston slap, or a tappetty-type noise which is much more apparent during cold weather.

I remember that MY97/MY98 engines are supposed to have low friction pistons - does this mean that they have a shorter skirt on the piston, and if so would this cause there to be more piston slap?.

If this is a common problem I won't worry, but I am curious.

ChrisL - did your dealer disclose why your engine suffered from piston slap? was it due to premature wear, an assembly error, or a component failure?

Cheers,

A.