vibration at 2.5k?

Giomani · Post by **Giomani** » Thu Nov 15, 2012 7:28 am

Here is a mystery for you gurus of Lude

.

It doesn't sound too bad, but when I'm reving down normally under load it sounds like there is a vibration noise coming from engine area when I drop to 2.5k. It doesn't happen above or below these revs or when reving up. I'm not feeling anything and apart from this slight sound everything runs smooth and purrs nicely. Any ideas cuz I can't make it happen and be looking in the engine bay at the same time... This is on my A8.

Post by **NafemanNathan** » Thu Nov 15, 2012 8:32 am

Check your engine mounts and all belts and pullies.

Post by **vanzep** » Thu Nov 15, 2012 8:40 am

It will be your exhaust - id put money on it
I had similar noise at 2.5k revs and it was loose bolt and washer at the manifold/downpipe area.

Post by **lewd lude lover** » Thu Nov 15, 2012 9:11 am

every lude i have owned had a slight 'wobble at about 2.5k. you could only feel it if you held the revs real careful like, hit 2.5 and the car would gently 'wub' with the engine. If this sounds like your issue then dont worry. If its more than this then get in there and take a look

littlefeller · Post by **littlefeller** » Thu Nov 15, 2012 9:19 am

vanzep wrote:It will be your exhaust - id put money on it
I had similar noise at 2.5k revs and it was loose bolt and washer at the manifold/downpipe area.

yep i second this, i have also noticed that if you have a hole in the system somewhere there is a sudden change of pitch at 2500 rpm on rundown, infact most cars do this with a hole in the pipe

Giomani · Post by **Giomani** » Thu Nov 15, 2012 10:30 am

Hmm, I do have a hole, but that's in the backbox (ongoing saga)

I'll check the rest of the zorst today cuz I have been bashing it around trying to get my back box and then the mid section off. (I've been defeated on both counts).

If its mounts/belts/pulleys, that might bring my belt change aspirations a little closer..

Thanks for the wisdom guys, ill let you know what I find.

Post by **Merlin** » Thu Nov 15, 2012 10:33 am

Have you had your head in the engine bay while someone holds the revs at 2.5K?

mercutio · Post by **mercutio** » Thu Nov 15, 2012 10:37 am

could be a loose heatshield or a damaged exhaust rubber or an engine mount on its way out

Supermarine Blues · Post by **Supermarine Blues** » Thu Nov 15, 2012 11:09 am

lewd lude lover wrote:every lude i have owned had a slight 'wobble at about 2.5k. you could only feel it if you held the revs real careful like, hit 2.5 and the car would gently 'wub' with the engine. If this sounds like your issue then dont worry. If its more than this then get in there and take a look

Having smoothed the engine up to that point, the balance shafts create an off-phase harmonic and the engine also 'sticks' slightly at those RPM due to the wasted power. I think it does it again about 5,000 and probably around 7,500, if you were that unsympathetic.

Of course, it also shakes your exhaust system too, and if it is getting a hole in the back box or loose baffles, it with then be most noticeable.

Post by **lewd lude lover** » Thu Nov 15, 2012 2:54 pm

^^^thats exactly what it feels like. glad iv not been fooling myself three cars on the trot.