Knocking noises!

My cars developed a knocking noise today when going over bumps or when you reach about 30-40 under mild accelaration.
It sounds like a metalic noise and appears to be coming from just over my shoulder by the bulkhead.
It gets worse when turning left but stops when turning right.

At first I thought it was something on the wheel which was tapping the undertray but cant see anything.
But then on the the way home from Uni I thought what about the cold air feed to the alternator and I checked and hey presto… It had come unclipped and un-stuck from the O/S clam vent and was free to bang whatever it wanted

So I’ve just spent the last hour in the rain re sticking in in place and put an extra cable tie on to stop the clip coming off and Ive just been out in it and…

The noise is still there

Everything seems ok around where the knocking is coming from ie manifold heat shield etc but got fed up and wet so came in to ask the clever ones.

Any ideas

Thanks in advance


Does it sound like something loose and ratling around or is it more like something mechanical and worn? Is it highish pitch tap or a low pitch thud kinda knocking?

What about you take a knowledgeable passenger out and get them to pin-point where its coming from - i’ve found it very difficult to pin-point noises from the drivers seat whilst on the move on my own.


It started this morning just all of a sudden. I’ve been wondering if something has broken.
It sounds like something hitting metal ie the undertray but cant see anything. It did sound at first as if the frequency speeded up the faster I went which got me thinking it was something wheel related. I havent had the u/trays off yet but already got pretty filthy on the drive looking everywhere I know and couldnt see anything obvious apart from the air feed to the alternator… but at least now Ive fixed that before it fell off

I was always having knocking noises etc on my Elise and so far Ive had a few on the Exige too but this one sounds a little more painful to the wallet.

I think a knowledgeable passenger is probably a good call though

Any Exigers fancy a drive and cuppa at my house Saturday

Or a beer


does it speed up with road speed or engine speed?

Also you need to tell us exigers where you are so we can come get that cup of tea


It was speeding up with road speed and it seemed consistant with wheel revolutions. A thought I had was if it was a nail in the tyre side wall tapping the undertray or something but cant see anything

Im in Brum! Its quite a drive just for a cuppa.
I could always book you a cheap flight

If not I’ll bring a flask to Oulton on the 12th Dec


If the stone hasn’t fallen out of your caliper by the weekend pop round and we can have a look …

Can put it on stands and run the engine/transmission and listen while not moving - should show up then …

See you



If it is a stone stuck in the caliper, try reversing the car, then braking quite hard. You may have to do this a few times, but it may shift the blighter!

If not, Dr Dovey will sort you out, I’m sure.

Cheers lads,

Ive used it today just to see if I can see anything in the daylight… And its dry… better than last night… Dont you just love rolling around on the floor trying to fix your car when its peeing it down.

Anyway. Even though I thought it seemed to be consistant with the wheel, its not…
It definately sounds as if something is broken banging around against something but I cant see a thing. It does get quicker with speed but I think thats more down to the wind or vibrations.

I had a look quick look this morning before I came to work but couldnt see anything…

Sorry boss Late again

Andy, Thanks for the offer.

I’ll have a look Saturday morning and if Im even more confused (Probably will be) I’ll give you a ring

Have you ever wondered what it would sound like if you inadvertently left a spanner or screwdriver somewhere in there and it slid down onto the undertray ??? Unless you have done all the work on the car yourself, this could be the answer…

Silly, I know, but if you take off the undertray, you may just be surprised…

It definately sounds as if something is broken banging around against something but I cant see a thing. It does get quicker with speed but I think thats more down to the wind or vibrations.

It’s not an engine mount is it??

How about a broken Air Con pipe? That’s just over your shoulder and can bang around if it drops down.


And they are known to break…

Uldis (no aircon faction)

Air CON !!

I too was wondering if it was an engine mount. Ive thought for a couple of weeks that the engine seemed to be moving around a bit more than usual. First thing to check I think

I know for sure its not the con air pipe. (I presume its similar to the one cooling the alternator which Ive already fixed) My cars one of the early ones, No comfort cooling� sorry comfort warming in my sauna! Its great at the moment though Ooh er Central heating

It could well be something dropped in the engine bay. It would be nice and simple if it was� Fingers crossed

I dont like the look of the forecast for tomorrow though…looks fun doesnt it… Somehow I think me might get a bit wet

Please Santa, Can I have garage for Christmas�. And a Honda Engine

Forget the Honda engine, there’s plenty to be extracted from the one you have…


Forget the Honda engine, there’s plenty to be extracted from the one you have…

But Uldis, don’t the Honda conversion kits come with new tougher driveshafts??! Something I would have thought may interest you at the moment.


Only joking. I think the engines an ideal match to the car anyway.

And I think the cars perfect. Always have ever since I clapped eyes on it and drove it.

Please Santa, Can I just have a garage for Christmas…

Or a big umbrella

Specialised Car Cover - Waterproof & Breathable, sorted!

Can you believe it, It was sunny… No rain anywhere… Yippee

Anyway, After spending several hours head scratching and swearing and being followed by PC Plod while I was out weaving around the local roads trying to find the knocking… (Long story) I’ve found the problem

ONE BIG NAIL sticking out of the side wall!!!

Luckily its not done any damage apart from the tyre.

Id been looking everywhere and was about to put my O/S rear wheel back on when I felt the nail which had squashed itself partly into the tread. Its right on the corner of the wall/tread though so repairing is definately a no go
But hopefully should be getting a set of 39’s very soon anyway

I Think Ive solved another problem while I was under there anyway so the day wasnt a total loss.

Ever since I bought the car Ive been having bad oil smells when driving. The oil breather kit which had been fitted had no vent pipe expelling the fumes to underneath the car. The catch tank had the blue silicone hose going into it from the engine but the outlet from the tank was just open venting right under the cabin rear window…

The breather kit and catch tank were fitted at the factory a year or so back so I presume they are the proper Lotus parts.
How have you guys done it?

Ive now put another pipe from the outlet, down the side of the engine bay to vent the tank so hopefully a sweater smelling Robbo when I get to work in future

Well when I get my tyres sorted anyway