Tapping engine sound.

[Graham Piccinini]

I hear the the variable tapping sound and wonder what it is. Got my guesses, but wonder what y'all say, or if anyone knows for sure. It's not a constant sound, comes and goes, and only at idle.
The vehicle is a 2009 Hyundai Accent. 1.6L/5MT. the sound can be heard at the following times in the video:
- 00:55-01:35
- 1:45-1:56
- 2:09-2:38
- 2:48-3:00
- At 3:08 the A/C compressor was turned off. The tapping sound continued.
- 3:25-3:30
- 3:36-3:50
- 3:58-4:07

 

[spasm3]

VVTI solenoid or sprocket?

 

[Greasymechtech]

Switch to a thicker oil and see if it masks the noise, especially if using a 20 or 30 grade. This is where a 0w40 or 5w40 would be a good test run for 3000 miles.

On a cold engine, remove belts and run engine, for no more than a minute or 2, to isolate and rule out failed or failing belt driven components. My alternator once had a variable tick, as did PS pump, A/C compressor, water pump(with a broken blade),...

Check the factory service manual to see if the engine requires valve adjustments.

 

[OilUzer]

Can it be piston slap? Does it make the sound when it's warmed up?
Or low oil pressure issues?

 

[Graham Piccinini]

Can it be piston slap? Does it make the sound when it's warmed up?
Or low oil pressure issues?

I've heard piston slap before, and it sounds more consistent. This though seems to be a valvetrain sound... Either VVT related, or hydraulic lifters maybe? Idk, which is why I'm here. No oil pressure gauge, but "idiot light" goes off instantly after startup. And again, when I witnessed low oil pressure situation in other engines - the sound was more consistent and throughout the whole RPM range. Not the case here, it seems.

Switch to a thicker oil and see if it masks the noise, especially if using a 20 or 30 grade. This is where a 0w40 or 5w40 would be a good test run for 3000 miles.

On a cold engine, remove belts and run engine, for no more than a minute or 2, to isolate and rule out failed or failing belt driven components. My alternator once had a variable tick, as did PS pump, A/C compressor, water pump(with a broken blade),...

Check the factory service manual to see if the engine requires valve adjustments.

Currently got a ~xW30 frankenbrew in there, with a 16oz dose of Rislone engine cleaner. But sound seems to be more pronounced than it was on 0W40. I think... Will confirm or deny this once I do an oil change with 0W40 again. As mentioned above - this sound is only present at idle, whether cold or fully warmed up. Oil filter is upside down-ish, so shouldn't be draining back into the pan. But sometimes the start-up rattle (only present for a split second in this video) seems to last longer, up to 3-5 seconds sometimes. Rare, but did happen a handful of times in winter time.

 

[Graham Piccinini]

VVTI solenoid or sprocket?

Part of what im suspecting. But not knowing for sure does make it a little alarming.
Just trying to find out if that's normal for G4ED engine, or if I got an issue brewing and this is the first indicator of it.

 

[Plawan]

It’s an appropriate time to try an engine flush I think. You could continue with the Rislone as well. A sticking hydraulic lifter is always a first suspicion for me on a car that has them. Definitely sounds like a valve train tapping to me.

 

[Bottom_Feeder]

I'm usually not one for recommending flushes or snake oils, but using a large dose of MMO at the end of each OCI on my wife's '02 Corolla over the years seemed to make a big difference in valvetrain noise. No idea if it was that or the cheap synthetic oil I was using in it. Whatever did it, it worked. It didn't 'fix' it but it reduced it significantly.

The fact that the noise comes and goes tells me it's not piston slap which should only occur when it's cold and eventually go away once it's warmed up a bit.

Hydraulic timing chain tensioner going/gone bad?