Piston slap, Lifter or rod?

I have read over the forums here & other places. I am not able to get a real diagnosis.
I have a tapping that is there right at start, when revved or under power driving.
I have tried different weight oils, MMO, Seafoam (Oil & intake).
I was told it's a stroker, but only have a recipt for a "Rebuild".

This all started after the electric fan quit on me & the engine overheated pretty bad.

Since then, it has had this tapping that does not change tone vs RPM.

I have worked with metal for decades & I seem to hear a more tinny sound, than a "Thunky" sound.

Took the valve cover off, found the bolts have been overtightened, as the bridges were twisted. For the moment, I have straightened them all out & properly torqued them with washers & all are straight.

Tried the stethoscope probing around & cannot define the location.

Also, a rebuilt distributor was installed, as the original was wobbly.

I am hoping that liftersand/or rockers/pivots/bridges/pushrods would fix it, but not sure it's worth throwing parts at it just to have a bad wrist pin or piston.

I have read so many forums that I am a bit overwhelmed.

Thank you for any assistance & help.

Ed

You need to probe the different areas with a mechanics stethoscope. A piece of long pipe works good for some of the areas.

Oh, 1996 XJ 4.0L

Ed

RCP Phx said:

You need to probe the different areas with a mechanics stethoscope. A piece of long pipe works good for some of the areas.

Click to expand...

I was trying that, but it got too hot out today. Been at it for 5 hours here in Vegas. I will probe better tonight.

Thank you.

Ed

Does the noise decrease as the engine warms up or it it the same in all operating conditions?

It stays the exact tone through the RPM/loadrange.
It is there at startup hot or cold. Shortly goes away. Any revving out of gear will bring it. Driving brings it. Idle with foot on brake/stopped/ in gear, I cannot hear it.

Thank you,
Ed

lazyxj said:

Does the noise decrease as the engine warms up or it it the same in all operating conditions?

Click to expand...

If the same tone while driving, would that be towards lifter/pushrod/rocker?

Thank you,
Ed

In addition to a stethoscope, a rubber hose can help find the general area. Have you ruled out a cracked exhaust manifold or just plain noisy injectors?

lawsoncl said:

In addition to a stethoscope, a rubber hose can help find the general area. Have you ruled out a cracked exhaust manifold or just plain noisy injectors?

Click to expand...

Yes. I replaced the In/Exh gasket. Had no tell tale of leaks. Niether did the manifold.
I have also pulled all injector plugs with no difference in the noise.
I will go over it tomorrow night with the stethoscope.
I'm thinking valvetrain, as one would think it's tone would change with load if it were a wristpin or piston rock?

Thank you,
Ed