Noise question

[charlie]

I've been listening to this knock in my truck since I bought it. I have had several ( qualified ) people listen to it. The answers I get vary from rod knocking to piston slap, to wrist pin, to valve train noise.

After crawling all over this truck today. I can see that the engine has been out, (looks like it has been).

I put a stethoscope on it today and pinpointed the noise to the top of the block on # 7 piston. The loudest point is just below the head gasket .

My first thought is piston slap.

The noise does get a lot quieter after it gets to running temp.

Any thoughts would be appreciated.

Thanks
Charlie

[wesman]

Hard to say without hearing it, but in the area you mention I'd guess that it could possibly be injector noise, valve train noise or piston slap as you described.

[charlie]

As far as the sound in question, it sounds exactly like a rod knocking, just in the wrong place. And I can hear the injectors as well as this noise.

Charlie

[Tex Arcana]

Seems like it's the typical piston slap we get with these motors. Mine sounds like a thrasher when it starts up, but seems to be fine otherwise; and my old '97 5.4 was the same, 'cept it was #8 that was clattering.

To me, it *sounds* too "light" to be a piston slap, but given it's an alloy piston, that makes sense. I think a rod knock would be a "deeper" or "heavier" sound.

[RUNVS]

Ah....... the old "marbles in the engine" noise. Yep, it's piston slap and damn near all Lightning motors have it. Goes away once the engine warms up.

[charlie]

Ah....... the old "marbles in the engine" noise. Yep, it's piston slap and damn near all Lightning motors have it. Goes away once the engine warms up.


Thats good to know. But at this point, it don't matter. I'm building a new engine. All forged, and better heads. And maybe a better blower by next Oct.


Thanks for the input guys.

Charlie