Engine knock... Does this sound familiar?

[01001010]

Ok, needing some help here guys...

I'm working on a 2.25 petrol engine with an interesting knock. I'm going to try to record a sound clip so you guys can hear. In the meantime, an explanation will have to do...

There is a knock that doesn't follow any pattern. With the valve cover off, I can hear that it's definitely coming from the valve-train...maybe the first 2 or 3 valves from front to back. I'll check clearances as soon as I can find my feeler blades.

EDIT: Nvm...file wasn't the correct type for YouTube

[01001010]

Ok, here's the vid...

http://www.youtube.com/watch?v=C5QiTyNyxmc

[SafeAirOne]

If the engine wasn't running so smoothly, I'd almost say it sounds like the "snap" of a leaky spark plug wire arcing to ground.

It seems like it's a one-click-per-two-revs noise, so that should narrow it down.

[bkreutz]

Sounds like a valve sticking and then snapping closed, and I think I see a matching hesitation in the lowest rocker arm in that film clip. Just a guess on my part. (without being there myself, you can usually tell a sticking valve by looking for a fluctuating needle on a vacuum gauge.)

[01001010]

Wow...thanks for the quick response guys.

AirOne... I know exactly what you are talking about but this definitely sounds like metal slapping metal.

bkreutz... That's the first thing I thought but it seems to sound louder on side opposite to the valves. This still remains high on the "Culprit List" though.

[01001010]

Could there be a faulty tappet?

[01001010]

Bump

[SalemRover]

When you rev the engine around 7 seconds it seems to stop for a moment. Is the sound consistent at all rpms? Sounds like something valve train related. Does the exhaust have any clues through smoke, smell or backdraft (if an exhaust valve is sticking).

On an unrelated topic, is your name 01001010 the binary equivalent of the ascii number for the letter J? Just curious.

-Jason

[I Leak Oil]

Could be a sticking valve. Could be a weak valve spring. Could be a worn rocker shaft bushing. Try turning the motor with a crank handle and have someone watch the suspect valves to see if you can pinpoint it.

My wife just asked me if I was watching a video of a steam engine. Told her it was a rover engine. She said "Oh, not much difference".....they just don't understand....

[SafeAirOne]

Can you pinpoint the location of the noise using a short length of hose like a stethoscope? An even better alternative is to get a $10 mechanic's stethoscope, which has a metal probe that you can place on different parts of the engine to pinpoint the source of an engine noise. Extremely effective! Watch out for the radiator fan when and if you do this.

Pinpointing the exact location that the noise is coming from is essential in diagnosis, Otherwise, "the engine is the problem" is probably the best anyone can do with any accuracy.