Identify this nasty noise for me

Trackphotos · Postby **Trackphotos** » Thu Apr 03, 2014 9:44 pm

So after last midweek night sprints, on the drive home I noticed a rattling/knocking 'ting' kind of noise. It would only occur while braking, or while turning left, so it seemed to be front/right of the car. After pulling the wheels off, removing the plastic undertray, looking and finding nothing, I put it back together and it's gotten worse. Now it does it with every slight bump in the road, and even at idle if you park on an uphill slope at all.

Any suggestions? Unable to pinpoint where it's coming from, other than 'down'.

Vat · Postby **Vat** » Thu Apr 03, 2014 10:01 pm

Really distinctive noise - just thinking on what down there would make that kind of sound. Maybe get in there with a screw driver and starting tapping things to try and replicate the noise?

davekmoore · Postby **davekmoore** » Thu Apr 03, 2014 10:06 pm

Please be careful with that screwdriver if you're doing anything with the engine running!

manga_blue · Postby **manga_blue** » Thu Apr 03, 2014 10:19 pm

NFI but the high frequency suggests it comes from somewhere outside the engine, or at least not deep inside it. I'd try ramming a soft plastic tube in my ear and moving the other end around the engine to see if I could get a better fix on the location. If that doesn't help then I'd try touching various bits with a stethoscope.

Trackphotos · Postby **Trackphotos** » Thu Apr 03, 2014 10:26 pm

Cheers for the replies. Certainly seems to be external, car drives as normal, and no change whether radiator fans on or off, AC on or off. More investigation tomorrow I suppose

Vat · Postby **Vat** » Thu Apr 03, 2014 10:38 pm

davekmoore wrote:Please be careful with that screwdriver if you're doing anything with the engine running!

Fair point! Please don't do this when the engine is running!

Trackphotos · Postby **Trackphotos** » Fri Apr 04, 2014 6:36 pm

Found the answer today. Turns out it's quite a bit easier to spot when you're working in daylight and have someone to blip the throttle for you while you're under the car.

This little metal bracket is supposed to stop some little rubber hose from moving around at the front/bottom of the engine. The bolt has fallen out at some point, and now the hose supports the bracket instead. It rests about 1-2mm from the crank pulley. Every time the RPM goes up, the engine stands up a little on the engine mounts and pushes the crank pulley into the bracket, spinning it around straight into the nut right next to it. Ting.