Rattling at idle - problem
 

I have a 2013 Accord EX-L with 56,000 miles on it.

About 1,000 miles ago I noticed a problem that seemed to occur over night. I started the car (cold start) and the engine or under carriage (can't tell where exactly it's coming from) made a weird rattling sound for about 5 seconds then go away. I would put my car in drive, drive down my street and when I came to the first stop sign at a dead stop my car would rattle again for about 2 or 3 seconds. Then after that it would not do it again throughout the entire drive.

This happens every day now and has been for the last 1,000 miles. The car will rattle upon starting. When I drive the rattle will go away, then when I get to the first stop sign on my street and come to a stop the car will rattle again for a few seconds before going away and then it won't do it again the rest of the drive.

So the car only rattles at idle and seems to only rattle when cold and then disappear.

Any ideas what this could be? At first I thought it might be something loose in the engine or under the car (loose heat shield?) but that wouldn't make sense if it only does it right when starting the car and then not again right?

See if you can get someone to listen under the hood when you first start it. Noises can travel around real funny ways inside the cabin.

Exhaust heat shields just beginning to come loose might quiet down after the pipes heat up & expand.

Idler pulley for the alternator belt? That can get quiet when it warms up, and someday it'll get louder and continue making noise after warming up.

Is it a V-6 or 4-cyl engine? If 4-cyl I wonder about timing chain? However 56k is way too soon for that. But hearing it with the hood open & standing right there is a good way to rule out the timing chain. Maybe even use a scrap piece of garden hose as a poor-man's stethoscope?

It is a 4 cylinder. How would I identify if the idler pulley for the alternator belt is loose? Is it just a visual inspection to identify or is it more than that? Also how can I identify if the timing chain is loose?

First thing is to pinpoint the location of the sound.

If you've ever replaced the alternator belt, then you know how to release the tensioner & slip off the belt. Then just grab the tensioner pulley to see if it's wobbly or anything like that. With the belt off you might give the alternator a spin & listen to that as it coasts to a stop. Same thing for the pulley on the AC compressor.

Timing chain is inside the aluminum cover on the non-transmission end of the engine. Stethoscope or hose can pinpint the sound. I think it's more likely you'll hear something underneath the car like a heatshield.

Could the sound have been made from really dirty or low oil?? Only reason I ask is because my car was due for an oil change and according to the maintenance reminder I was at -250 miles. I changed the oil and filter myself last week and miraculously the rattling sound at start up and idle has completely gone away. The only thing that has changed is the oil and filter change. Weird.

No & Yes.
I doubt it would be from dirty oil. I ran oil at least as much beyond & had it analyzed - they said it could have gone longer.

I'd sooner believe it can be caused by low oil level. How was the oil level on the dipstick before you changed it?

Did you ever figure out what the issue was? About a year ago I was bringing my car (‘13 Accord) to the dealer and at every service would ask them to tell me what the sound was from but they could never replicate it (at that point it was only happening at start-up).

Now, a year later, it’s longer at start-up and also does it when coming to a stop for the first couple of times after start-up.

Rattling at start
 

[2017 hybrid touring
Just bought a used hybrid and it's also making the rattling noise for a few stops once it warms up it goes away has anyone figured out what that noise is I've taken it back to the dealer for now to try to replicate the noise for him any help would be appreciated

QUOTE=PackManDan;376873]I have a 2013 Accord EX-L with 56,000 miles on it.

About 1,000 miles ago I noticed a problem that seemed to occur over night. I started the car (cold start) and the engine or under carriage (can't tell where exactly it's coming from) made a weird rattling sound for about 5 seconds then go away. I would put my car in drive, drive down my street and when I came to the first stop sign at a dead stop my car would rattle again for about 2 or 3 seconds. Then after that it would not do it again throughout the entire drive.

This happens every day now and has been for the last 1,000 miles. The car will rattle upon starting. When I drive the rattle will go away, then when I get to the first stop sign on my street and come to a stop the car will rattle again for a few seconds before going away and then it won't do it again the rest of the drive.

So the car only rattles at idle and seems to only rattle when cold and then disappear.