Micra K12 1.4 Auto - rattle/grinding when cold

[MickeyLuv]

I'm new to Micra ownership and prior to signing up checked throught the forum to see if I could find any answers, but I'm stumped....

I've just acquired a 2008 car with 25,000 genuine miles from a family member. When cold the car makes a grinding noise - bordering on a rattle - which can be heard inside the cabin. Oustide it doesn't sound as bad.It doesn't do this at all in neutral, only in drive or reverse. The noise increases with revs. When the car is hot it disappears completely.

Just spent an hour in a pit underneath the car. My partner has been putting it in and out of gear and I can't locate the source. I've repeatedly gone over the heatshields and exhaust to check for any noise. Initially I though it may lie around the alternator area but can't say for sure. When the car is put in neutral from drive the noise doesn't instantly stop and takes about a second or so to decay.

Does anyone have any suggestions?


Edit: I took another look at this today and the noise is definitely from the alternator end of the engine. I also used a mechanic's stethoscope to probe the cam chain cover and the noise doesn't appear to be coming from there, but I can't pinpoint it. Certainly something either to do with the shift in engine position with drive engaged, or the change in loading of some component.

 

[alexvanwyk]

I have a similar issue when I switch the Aircon on. I think its the fan belt tensioner. I feel the vibrations through the gear lever. I took the fanbelt off and started the car, and listened to the sound of silence. Put the belt on again, and it was rattle all over.
I have been living with it for about a year now.
Let me know if its the same issue.

PS: the noise became a bit less when I fitted a new fan belt

 

[MickeyLuv]

I think the next step for me is to remove the belts. It would be really nice if it was only belt noise. Why it only does this when in gear though beats me, though the engine does physically move an inch or two when in gear so there may be something going on. It certainly is annoying.

 

[MickeyLuv]

After another hour underneath the car I finally located the problem; the rubber mount that locates the resonator.

This had become elongated and hardened. With the car in gear, the exhaust moves and vibrates against the lower edge of the mount. Because its hardened it transmits noise to the driver's side of the car and sounds like it's coming from the alternator area. When everything is hot it doesn't do this. I experimentally cut some rubber tube and packed out the oversized hole in the mount and this fixed the problem. Just been out for run and no more noise. Next job is to order a new mount.

 

[alexvanwyk]

Thanks for the update. I will check mine, but I am fairly sure its not my problem. Will keep digging.