Shuo Wang

Recently I noticed this rattle noise coming from the engine bay. And the noise seems to go away or become unnoticeable once throttle is applied. Could this be timing chain rattle? I checked oil level and it’s full.
video link (sorry mbworld won’t allow me to upload one)
https://youtu.be/Tk0C5_jtUdo

ml3504matic____

No that sounds like a bad pulley. Rattle typically only occurs on startup

pierrejoliat

Unless you let it go long enough that the tensioner is toasted completely? My '12 rattles on start-up for 15-30 seconds, has 30k miles and original chain tensioner, seems to rattle less with 5W30 than 10W40, like 10 seconds or so.

I could be wrong, They did fix it on my '13 under extended warranty and it doesn't rattle on start-up

Blkvip

try taking the belt off and see if any pulleys have excess movement. if you haven't done the pulleys and tensioner id do it. cheap and peace of mind.

Shuo Wang

I've never heard any rattle on cold start on this car. My audi s5 had cold start rattle and it was fixed by a newer timing chain tensioner, thankfully under warranty.
I'd probably get an auto stethoscope and tap it on different places to figure it out.

Shuo Wang

The pulley and tensioner were replacement 10K ago with OEM parts, so I doubt it's the issue. I could be wrong though. I'll give it a try this weekend.

Baltistyle

we mean the timing chain tensioners…

Shuo Wang

Update, brought it to a mechanic. The rattling noise was caused by a failing belt tensioner. So it failed after only 10K miles. hmm.

CaliBenzDriver

You had your belt tensioner and idlers replaced with OEM and less than 10kMi, it all failed again... that's when you invoke the free "repair warranty" -or find a new place with skilled techs & genuine parts.

I can't believe this failure being so short is anything remotely normal.

Shuo Wang

It got replaced 2 years ago and the shop only provided 1 year warranty, it really sucks. I am going to a new place for this repair...

Senecat

Guide pulleys and tensioner are a 15 min job. Tensioner is a Gates unit you can get on ebay for $30. Don't bother paying OEM price.

mercyfan

What they replace to fix it Pierrejoliat?

pierrejoliat

Timing chain guides and tensioner, I bought the extended warranty on that car, because I was still working and driving, so I put 20k a year for the first three years and then it was 3-4k a year until now, which is 85k miles currently. If I remember correctly it was at 49k miles. I'm pretty sure FCP Euro has the guide and tensioner as a kit sold together, I will need to do my '12 at some point, but I just turned 31k miles on that one, I still have the factory brake pads after ten years, 8 mm left!