Is partial rod knock possible?

[Neejay]

I came across this video http://www.youtube.com/watch?v=4G-PgNielZY and it sort of sounds like my car sometimes when I FIRST start it up from a cold start but not quite that loud. It kinda scares me, so if I cut the car off and start it back up, it's not there anymore. Side note, I also have a dented oil pan. I have another one, but I haven't put it on yet.

Is partial rod knock possible? Wouldn't it sound that way all the time, and especially if you revved?

[projectRDM]

Not really. There is virtually no oil pressure at immediate startup, so you might hear what sounds like rod knock, it's more than likely just a little bearing slap due to being cold and unlubed. Though it's not a good sign, a lot of older engines begin to have a little bearing play due to age/mileage. As soon as there's pressure you shouldn't hear it anymore. The dent is the oilpan is only aggravting the problem since it's starving the pickup though and I'd get that fixed before it does get worse.

[Neejay]

Yeah, it does sound like a metal slap noise. Dammit...I'm going to have to do it in my apartment's parking lot. I need to change my motor mounts anyway, so I'll already be jacking up the engine. Might as well get the oil pan changed. Thanks man.

[samplesurf]

piston slap isnt always bad according to GM, most newer chevrolet trucks with larger displacement gas engines such as the 6.0 have been known to have noticeable piston slap upon startup that goes right away thereafter and they dont seem to have a problem with it

[irax]

yeah but those larger displacement motors dont rev much higher than like 5k.