4age making a tapping noise

[Moebius]

Car - AE71

motor / part in question - bigport 4age

problem - Making a tapping noise

occurs/started when (if applicable)- Happened when I started it up for the first time in a few weeks. Was running fine previously.

I don't really know how to describe the noise other than a tapping sound. It doesn't sound to me like an injector ticking noise or an exhaust leak. I've tried listening to various parts of the engine with a rubber hose up against my ear and I can't pinpoint where it's coming from. The noise goes away when I rev the engine, but comes back immediately once it drops back to idle. I've only run it for a few minutes but it didn't seem to go away after warming up.

I've taken the rocker covers off and there is nothing that jumps out at me as being wrong. I checked all the valve clearances and they are all within spec, except one of the exhaust ones which is 0.03mm extra. The oil was changed only a few hundred kms ago, and still looks fresh both on the dipstick and in the head.

This is the best video I managed to get where you can hear the noise -

[Matt]

Usually exhaust or intake gasket leak causes a similar noise

[Moebius]

Hmm, okay. I think I've only had leaks further back so I don't know what it sounds like from one of the manifolds. Is there any way to pinpoint where a gasket leak is?

[maxhag]

look for black soot marks at joins/cracks/gaskets

[timbo]

What oil/weight are you running? Sounds mechanical to me, but do as stated and check for soot around the exhaust manifold. Was there much oil under the cam covers?

[sirsprinter]

Sticky lifter? One that failed to reach hydraulic pressure after sitting for a bit? Im curious too because mine is making a similar noise, but scarier.. yet to have it looked at. But good luck with your issue mate. Hopefully something simple

[Moebius]

There was a small amount of soot on the gasket under one of the exhaust ports, but it didn't seem major. I turned the crank by hand and all the lifters appeared to be okay from what I could tell.

I've got an oil pressure gauge and a stethoscope now so I'll see if I can narrow it down.

[Hen may possibly be a nut]

4AGEs don't have hydraulic lifters, they use buckets and shims.

[sirsprinter]

Cheers hen; ive already been corrected on that - i should have edited the original post.

*hen i thought you were replying to my thread where i posted a similar issue and incorrectly mentioned hydraulic lifters too lol

[Moebius]

Well after connecting the oil pressure gauge it was reading 71 psi while cold idling at about 2k rpm. Seemed a bit high, but after it had been running for a few minutes while I was searching for the source of the noise with the stethoscope, the pressure dropped down to about 40 or 50 and the noise started quietening down. So I dropped the oil and put some 10w-30 oil in and now the noise seems to have gone completely. Seems a bit odd to me, as I had run it for probably about ten minutes before that and the noise was still there, so I don't really know what changed.