trapin

I’ve noticed the last few times I’ve started my engine it makes a pretty noticeable knocking sound. It goes away when you rev the engine and once the engine is warmed up it’s gone. Please listen to the attached video, you can hear it clearly towards the end. What do you think this is?

warriorpluto

iTrader: (2)

There's no video. What you're describing is piston slap

trapin

Hmm....I thought I attached the .mov Video from my Iphone but it must not have taken. Can we not attach Iphone videos here?

Twin_Turbo

iTrader: (9)

Piston slap

trapin

Hey guys, just uploaded a Youtube video in the original post.

Twin_Turbo

iTrader: (9)

Is it me or am i hearing erratic knocking unrelated to rpm? As in non constant?

trapin

That's exactly what it is. Erratic knocking not related to rpm. When you rev the engine it vanishes, and once the engine is fully warmed up it's gone.

ghardester

Yes, I hear that in the video too. Is your exhaust knocking on something? Can you get it up on ramps or something and listen from under the car? I had a mystery knock once that I was sure was internal engine. It was the exhaust.