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MG MGF Technical - Rattle from my VVC

Only had the car a month and this is my 3rd thread! Obsessed or what!! I have a 2001 VVC and notice a quite load rattle on start up at about 1100 RPM on fast idle. It goes away when I blip the throttle and after about 1 minute. My feeling is it is emulating from the exhaust area but couldn't be sure. Seems like a resonance type of rattle rather than something mechanical but am worried about VVC mechanism or something else more sinister. Anybody got any ideas to put my mind to rest. Any thoughts much appreciated
J Boag

Could be the cat But maybe someone close to you could have a listen.
Andrew W Regens

Most likely to be one or two hydraulic lifters taking their time filling with oil, which temporarily leaves excess clearance on the valves, resulting in the tapping noise. As you blip the revs, the oil pressure rises and the lifters fill properly and remove the excess clearance, and once full they remain so until the engine is stopped.

In many cases an oil flush will have a positive effect; slightly gummed up oilways may be the reason the oil isn't getting through at idle speed/pressure, or gumming up of the valve that controls the flow of oil into the lifter chamber. Re-fill with Castrol GTX Magnatec or any other good 10w 40 oil.

Unlikely to be a failed camshaft bolt, but you can check them fairly easily - remove the engine cover, unbolt the top half of the timing belt cover and check the bolt on each camshaft sprocket is tight. But the fact that the noise goes away after a period of running does point more towards lazy lifters than anything being about to fall off.
Mike Hankin

I agree with Mike - this is a very common 'feature' of any hydraulic valve lifters.
Ted Newman

Thanks guys, really helpfull. I checked around the exhaust and Cat and coudn't find anything. I will replace the oil as you suggest, do I need to flush it before adding the new oil?
J Boag

Part of the exhaust has steel mesh around it. Mine makes a rattle at startup and gets a little quiter soon afterwards. I must fix mine soon, as it's annoying me.

Cheers
Branko

Branko

Most engine flushes are designed to be added to the existing oil, run for a short time, then drained out, hopefully with all the unwanted deposits dutifully dissolved in it. Very important to change the filter too!
Mike Hankin

As anybody out there removed the vvc device off the end of the camshaft. I need to know how to set it up to fit it back on, any help would be appreciated.
Martin

Martin, get a member of this BBC and check the archives.

One late I know who got it done was from Portugal
:)
http://www.mgfcar.de/k_engine/valter.htm
Dieter

The rattle could be the catalyst heatshield, it's only held on by one tack weld in each corner. Once they corrode it causes a tinny sounding rattle...

...until it falls off and is seen skittering down the road in the rear view mirror. At which point you think - so that's what it was!
Alan Brooke

Mine turned out to be either the strap that held the back box on had corrodded through and was "buzzing" or it was the braid of the flexi pipe section of the front exhaust down-pipe buzzing. Also have to say if you've ever had any brake pipes re-plumbed and they've bypassed the engine bay make sure the old ones aren't still attached as they were in my f and caused much confusion for a year before they were tracked down!
Leigh

My non-VVC has the tappet rattle when cold. It lasts for about 2 or 3 minutes before the oil gets up there. Several oil changes with Castrol Magnatec haven't made any difference so I'm ignoring it.

Mike
Mike Howlett

Martin, several years ago after an HGF my local garage took the vvc unit off despite being told it was not a good idea. It took them a loan of the MG service dvd, a special tool and five days to get it back together.
Ddraig

This thread was discussed between 20/03/2007 and 14/05/2007

MG MGF Technical index

This thread is from the archive. The Live MG MGF Technical BBS is active now.