Belt tensioner would be my guess. What's the mileage?
Put a stethoscope on all the moving bits on the engine, CAREFULLY, while idling. You should be able to isolate the ticking. Injectors, pulleys, pumps could all be suspects.
A primitive stethoscope could be a broom handle or screwdriver for a quick diagnosis.

 

Tensioner would have more of a squeak sound.

does the belt feel loose? You can take the belt off and rotate all the pulleys by hand to feel for a bad bearing Or something easily

it sounds like some mechanical like valvetrain or timing chain guide noise to me but it’s hard to tell on a video.

 

It may also me the aforementioned air pump bearing. My W124 cabrio made sounds like that before I replaced the bearing.

 

Maybe you can give us a video with the hood open. Whenever you are trying to diagnose a noise your first approach is to zero in on the noise. Maybe having the hood open we can determine if it’s from the front of the engine or back further. Could be a loose or failing bearing somewhere along the the belt drive or it could be a timing chain noise. Hard to tell.

 

We can't go on together with suspicious noises....

 

First of all, thank you for your feedback.

The car has 100,000 miles.

For me, the noise does not come from the front of the engine, it is more audible in the lower part. (Nothing on the cylinder head side either). But I will still try disconnecting the accessory belt.

I'm going to try to put myself under the running engine, to listen to the stethoscope, and make you a video.

 

A rod knock would also fit with what you describe and what is heard in the video, but at 100K miles, that would be extremely unusual.

 

As mentioned, I did some tests, with a stethoscope. It wasn't necessarily obvious but I still have a more pronounced knocking at the bottom crankcase/engine block on the last 4, 5 and 6 cylinders.
I also did the test by disconnecting the belt, it confirms that it does not come from there, since there is no change.

I'm afraid it's a connecting rod problem... Although this engine is not known for that!

A new video turning around the engine :

 

I seriously doubt it unless its been run out of oil at some point!
As mentioned prior noise from tapping lifters will echo down and resonate as if the noise is inside the sump. I would remove the cam cover and check them!

 

Change the oil to a high quality 5/40 synthetic and give her an Italian Tune Up.

 

I will be very surprised if it is a lifter problem. Sometimes I hear one knocking after a long stop, but it's just a few seconds while it reboots and it's not at all the same noise as it's now.
But I planned to remove the cover, to check my timing chain, it will be an opportunity to watch.

Regarding the 5w40 oil, I had already tried it on my very first oil change, but I found the engine really noisy. So I switched to 10w40 and it seemed better. If I had to give it a try, I would tend to take a higher grade (15w50?)

 

After listening to your video, the noise it too high pitched for a rod knock. Look for a pin hole in the exhaust system near the motor or loose exhaust manifold bolts. If you can, smoke test the exhaust system as a pin hole that can make that sound can be tiny and hard to find.

 

I think a black streak would be seen around the leak if there was one, and I didn't hear anything in particular when putting the stethoscope on the manifold. But it's a good idea to test with smoke.

Check the resonator assembly between the intake runners.

What do you mean ? I don't see which part you are referring to.

 

Even if it is a rod knock, if you change the bearings before you pound the daylights out of the bottom end, you'll be fine.

 

Check the resonator assembly between the intake runners.

 

You can kinda check rod related like this guy, around 5min (he has other videos on his channel, including noise, in this video his 3rd cylinder moves down a bit, later he found worn bearing)

I also had some weird ticking noise (maybe similar to yours but I dont remember exactly now) and I was hearing it best from ouside around wheel arch and inside car when idling coming from footwell and there was more noise when shifting in drive and not moving, In the end I found something was shaking inside drivers engine mount. Mount wasn't old so I changed it again the noise was gone. It took me almost a week to find it. Stetoscope didn't really help as I could hear this ticking almost everywhere..

 

lifters.
my 2 cents.
@lowesguy has a decent post /thread - not too long ago - on his noise (m103) issue.
Review his thread for a reference - well documented.

 

YES LIFTERS AS MENTIONED..!

 

Thanks for your feedback. The video of this Russian guy (as well as the others) is very interesting, luckily I'm not at that stage!
I also reviewed lowesguy's entire post.

I made a little progress on my side, doing an oil analysis. This brought out way too much lead and copper, so I have a bearing problem somewhere. (Connecting rod bearing on crankshaft? Connecting rod bearing on piston?)

Here is the detailed table that we obtain:


Also, by analyzing the soundtrack, I counted the number of knocks per minute, I get 354/min. That is twice less than the idle speed. It could be a lifter but I don't believe it. It could also be the explosion frequency in a cylinder, but I couldn't hear any improvement by deactivating the cylinders 1 by 1.

I don't see any other tests to do, except to take it apart to see inside...

 

Hi
Did you found the reason for engine noise?

 

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I am having the same engine noise after performing a head gasket and oil pan gasket repair.

Did you ever find a solution or cause of this noise?

I didn’t have a tick upon first start after the head gasket repair. After 3 min the tick began.

Still trying to figure it out.

 

More than likely a hydraulic lifter tick. When Mobil 1 was full synthetic, it had some really good detergent properties, and it had a good reputation for clearing up sticky lifters and eliminating the noise. I don't know if that is true anymore, I suspect it probably is.