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Hello, forum - I've got a question. A friend of mine has bought a 2000 Civic with a removed engine; it supposedly had some problem with the end of the crankshaft where the balancer mounts that required some welding - I don't know the details, but allegedly this was done and now it's up to my friend to put the engine back in the car. I'm pretty sure this engine is a 1.6, it's a SOHC and it's my understanding it came from the vehicle, or another of the same model.

He has put the crankshaft into the engine, presumably correctly, and everything is assembled (the engine is not in the car yet), but he asked me for help about this problem. When he turns the crank manually, there is a clacking every so often coming from inside the engine - hard to tell where, but it sounded to me like the cylinder head area - plus, the camshaft sprocket seems to "twitch" a little coincident with the clanking sound. I had him remove the valve cover and I discovered something that struck me as weird. As the (single) camshaft turns, for each cylinder, both of the exhaust valves are depressed together, but only one of the intake valves on each cylinder gets pushed down. The other intake rocker arm barely twitches, it seems completely disconnected from the first rocker arm, and that valve doesn't go down at all. It is the same for every cylinder. I haven't visually located a cause somewhere long the camshaft for the sound. But, is this action by the rocker arms normal? What might that sound be, if not something to do with the cam action?

Any help would be appreciated. Thanks ahead of time!

 
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Must be a VTEC engine, it sounds normal.

One intake valve rocker arm is left disengaged until VTEC is turned on at higher RPM.
Opening only one intake valve at low RPM promotes good swirl in the combustion chamber.


Valve spring pressure against all the cam lobes kinda pushes the cam clockwise or counterclockwise as you attempt to rotate it. It naturally tries to spring to rest in 4 positions, if you ever tried to turn the cam with a wrench you'd be able to feel this.

 
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That I am familiar with; the springs like to force the camshaft lobes off their most extended position.

I'm talking about an audible, sharp "clack" sound, which I'm not familiar with on any engine I've played with before.

 
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try doing a valve adjustment and then rotate it. maybe a valve is slapping back into the head as you rotate the cam.

 
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I have never been able to audibly tell if there is a loose valve when hand cranking the engine. It has to be running.