1G Need help: Possible rod knock / piston slap.

[Kdouglas89]

Hey guys, recently purchased a 92 talon tsi awd. I cannot determine if it's rod knock or the lifters. It sounds a bit louder than it should for lifters, but listening with a stethoscope, the lifters sorta sound insync with the noise.

Things i've tried:

Compression: 150 across the board

Rotating engine around by hand, I don't hear anything

I've pushed down on each cylinder with a screwdriver from the top, and everything feels sturdy / no noise.

Using a mechanics stethoscope, the noise sorta sounds like it's insync with the lifter taps, but unsure.

I have not drained the oil to check for flakes, and have not pulled oil pan to check from the bottom.

Really trying to avoid pulling the motor, but I will if I need to.

 

[brian9397gsx]

Well one way to determine if it is piston/rod knock is to take away load from each cylinder one at a time to determine which is causing it. There's two ways to do this while its idling either remove a plug wire or un plug the injector. If the noise goes away then it is indeed piston or rod. Do this one at a time reconnecting the unplugged coil or injector before moving on to the next cylinder.
In my experience removing spark works better than fuel but both work well. If the sound doesn't change than it isn't load dependent and it is most likely valvetrain. Piston knock is pretty uncommon but it does happen. I had an old focus with the zetec 4cyl that knocked like crazy after removing the cam cover and inspecting tappets and removing the pan to inspect bearings I ruled it to piston slap. I buttoned it back together and ran it for probably 5 years that way. But had it been anything more than just a work car it would've gotten fixed.