Strange metallic 'rattle' -Vectra DI - Richard P
I have a Vectra DI which when the engine is turned off, there is a fairly prominent metallic rattling type noise from under the bonnet somewhere. I am guessing it is perhaps the exhaust. However, when I start the engine from cold, there is a light metallic rattle when the engine is idling, but this stops as soon as the clutch is pressed. When the engine is warm and idling, this light rattle dissapears! I will get Vauxhall to have a quick look at this at its 30K service. I am just wondering if anyone has had any similar noises like this and what cured them. Thanks
Re: Strange metallic 'rattle' -Vectra DI - Bono Estente
Hi Richard.

Agree about the exhaust.

The light rattle in my experience (not vast, and not with diesels) will be the timing chain. They are never completely silent from new. What tends to happen is you can hear them only under certain combinations of 1.engine speed (in the lower ranges please God) 2.temperature and 3.load.
Hence when you declutch a small change occurs in 1. and 3. HTH.
Re: Strange metallic 'rattle' -Vectra DI - gwyn parry
Had a similar prob. with my Vectra, albeit it being a petrol 2.0litre. The noise was a metallic rasping sound which could only be replecated under certain conditions. I thought that it may have been 1. something trapped (stone or similar) trapped behind the cat, heatshield 2. The Cat itself, heaven forbid. Anyway took it to the dealer who indentified and rectified a blown middle box - according to him "they all do that".
Re: Strange metallic 'rattle' -Vectra DI - Richard P
Coming to think of it, the noise really is a light 'metallic' knocking or tapping sound which is only evident when the engine is cold and idling, but stops as soon as the clutch is pressed. The timing chain is something I did not think of actually, but the noise is a bit too loud for that to be the cause. I think the noise is actually louder right near to the nearside front wheel, but I will listen more carefully sometime soon! I still have a hunch that the exhaust is to blame. Apart from this slight niggle the car drives fine. Thanks for your help!
Re: Strange metallic 'rattle' -Vectra DI - Mike Harvey
The 'Getrag' gearbox fitted to some Vauxhalls used to rattle at idle just as you describe. (I'm talking 80's here) It was the gear teeth chattering together as they were not under load. Yes, they all did it, really!

" It's a feature Sir, not a fault"
Re: Strange metallic 'rattle' -Vectra DI - Moosh
Some rally cars back then used to chatter away loudly whilst on tick over, something to do with the limited slip diff.??
Re: Strange metallic 'rattle' -Vectra DI - Moosh
Some rally cars back then used to chatter away loudly whilst moving very slowly on tick over, something to do with the limited slip diff.??
Re: Strange metallic 'rattle' -Vectra DI - Mike Harvey
Rally cars tend to use straight cut gears which are staggerigly noisy- you know what reverse sounds like- but in all gears. LSD may well have rattled too.
Re: Strange metallic 'rattle' -Vectra DI - Flat in Fifth
Mike is right on this, plus the rattling on idle particularly with the old Getrag and ZF boxes is due to some gears being in constant mesh, and the rattling is from the backlash due to intermittent powere delivery and the gears not being under load.

The noise from slippy diffs, more like a creaking than a rattle, is due to the clutch plates gripping and slipping when one wheel is turning faster than the other, most noticable under low speed manouvreing. The degree of noise depends upon the amount of pretorque, by which I mean how much torque it takes to break the connection between the wheels.
Re: Strange metallic 'rattle' -Vectra DI - pete
Could be the exhast baffle plate as suggested , can be common on some cars
Re: Strange metallic 'rattle' -Vectra DI - Richard P
Thanks for the input, much appreciated. I think the light tapping sound is the gearbox, as a similar noise can be replicated when the car is warm and idling if I move the gear stick to the point of almost engaging gear, without pressing the clutch (not as far as to cause some nasty grinding noises!) When the engine and gearbox is cold, the noise almost stops if I try the same exercise again. The gearbox works fine BTW, no problems at all.
The rather loud rattle when the engine is turned off I think is something else, and is likely to be the exhaust. It has not got any worse in the last 5K miles or so and I will get the garage to give it a quick once over when the car goes for its 30K service. Thanks again!

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