Weird engine issue) vibration

Technical Area Engine, Transmission, Exhaust etc
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  1. My model of MX-5 is: 07 NC 2.0i sport
  2. I’m based near: Preston
  3. I’m looking for technical help or recommendations on: a strange engine sound

Hello fellow boaters, I have an odd issue with my 2 litre 2007 NC. The engine sounds more rough at idle, but fuel economy and power are fine so my usual garages hasn’t been able to find anything.

It’s obviously a petrol but with the bonnet up it sounds more like a diesel and I did double check service history and notice that the water pump/belt have never been done despite being at 85k.

Any ideas what it could be?

Videos in the drive folder below;
https://drive.google.com/drive/folders/1rWLW0XpCcOj7pwmdxRIa6zUE0ILbOrl3

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Has it just started making this noise?
The first checks would be auxiliary belt pulleys and tensioner pulley worn, they make a squeaking or grinding noise as they get more worn.
Check out the various threads on the forum, do a search and it’ll give you idea how they tracked down similar noises.
In short you can remove the auxiliary belt and start the car and run it briefly to check if the noise is still present.
BTW if you mean belt not been changed, the auxiliary belt then ok, if cambelt, these don’t have one it is a chain driven engine, so not much maintenance there. Of course some have been known to need changing because of rattling and wear but check your auxiliary belt first before continuing the investigation.

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Hi there, it started about 6 weeks ago, took it in for a full MOT and service to see if the garage noticed it, they didn’t, then I started querying it with other garages.

I did mean the auxiliary belt though, but I will check that first, thank you

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If doing it yourself check out the diagram below. The tensioner pulley the idler pulley above it and if you don’t have aircon there will be another idler pulley replacing that bottom right. Those are the ones that ‘could’ be causing the noise.
A suitable socket and bar on the tensioner should see it move to take tension off the belt for removal. The diagram also gives info for belt replacement/orientation.

1000001679

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Tha k you, I’ll give that a go soon, I just need to borrow some sockets from my friend first :rofl: