2008 JK - 3.8L V6 with 48,000 miles


The other day my engine starts tapping like I have a valve issue. I am out of warranty so I take it to my trusted local mechanic. He pulls valve covers off and to his surprise rocker arms, valve springs, all are rock solid. Engine looks very clean on the top side and nothing looks out of place.


My sounds and when ...
At first start up this morning I don't hear ANY noise. It isn't till it warms up (maybe 4-5mins) does it start to tap.
Tapping is dependent on RPM
Tapping is barely noticeable when cruising, but if you step on the gas it defiantly starts up.

I've read the stories about main bearing issues and a bit scared, but hoping that isn't it!

Anyone have any suggestions?

Here is the video of the sound.
http://youtu.be/Pgwf6vxcG1c
EDIT UPDATE:
Just got the Jeep back from Warranty Extended Service...

Lifters, Heads (They said valve seats were dropping) and Rod Bearings ...

 

Take it to dealer tell them you want a check and advise.probally cost $150 but at least you will know and it will be documented.this is what I would do.

 

Are you sure it is coming from the engine and not the transmission or driveline?
Did you check for the tapping in and out of gear?
Is it a manual or auto?

Could be a bunch of things.

Did your mechanic do a leak down test on the cylinders?
Did you check things like the harmonic balancer or any other moving part near the serp belt for clearance and balance?
Is the tapping speed dependant or only RPM dependant? That will help you further isolate

I would say it is important not to ignore anything like that before you find out the hard way on the side of the road waiting for a tow what it is.

First thing I would do is take a very good look at the oil and trans fluid if you have an auto. That can be a big give away as to if anything is wrong it those areas.
Next I would probably check the timing if you really think it is a knocking or tapping sound from the engine, and make sure the timing is changing under load appropriately
After that a full check of the driveline if you havent isolated anything yet
The next step really depends on what you have checked already.

Best of luck and hopefully you figure it out

 

It is an automatic.
It is defiantly RPM driven. If I rev the engine up at park the noise speeds up.
I will find out if they did a leak down test on the cylinders.

 

Is the tapping load dependant?
Does it tap the same in park at 3000 rpm say as if you starting off down the street and pushed hard on the gas at 3000 rpm?
Is the tapping consistent in that the same thing happens every time or is it more random?
Did you check for loose vacuum hoses or leaks?

 

My 08 3.8 had some tapping that turned out to be gummed up fuel injectors, just a thought.

 

The tapping is the same under a load vs not under a load.

It is only random in that some times it is VERY loud and other times it isn't as loud.

Also at first cold start you don't hear the noise.

 

Are you sure it isn't an exhaust leak?

 

I'm with this or one of the fuel injectors.

 

Does it sound like a rattle can ball bouncing around on the bottom end? Mine does this too? Subscribed!!