Intermittent knocking noise

[s1nn0n]

Hi all, I have an intermittent knocking noise coming from my engine. Today I replaced the inlet manifold, well I say replaced I removed the internals from it and replaced the spark plugs. I cant say that I noticed the knocking noise before, but then the manifold was probably causing it. The car drives perfectly, no hesitation and also idles perfectly. The noise in question, is as I say, very intermittent. It can happen when the car is cold, when its hot, and will come and go when driving the car. It sounds very much like the inlet manifold, but it cant be, and it still happens with both VIS unplugged. Any ideas please? I can try and get a video if it helps, but it doesn't always do it!:rant:

[POMPSKI]

Knocking? Or ticking? Are you sure it isnt just the purge valve?

[talkingcars]

If you've gutted the internals the vis wont do anything anyway.

[talkingcars]

Knocking? Or ticking? Are you sure it isnt just the purge valve?

This is simple to test, just unplug the purge valve.

[petet16]

The plug for the purge valve is on the intake just after the throttle body, when it starts tapping disconnect the plug, if the noise goes, you've found the cause.

[POMPSKI]

And if it is the cause, it is working perfectly fine :)

[petet16]

The purge valve is the black cylindrical bit just after the t/b, it has a pipe to the charcoal canister and a electrical plug

http://i4.photobucket.com/albums/y142/petet16/100_1341.jpg (http://s4.photobucket.com/user/petet16/media/100_1341.jpg.html)

[s1nn0n]

Thanks for the response guys, but no its not the purge valve, it does make a noise but still present with it disconnected. Its more of a knocking noise really, maybe loose spark plug, but wouldn't be intermittent. I went out to the car earlier with a screwdriver to pinpoint it further and was quiet as a mouse, although when driving along earlier sounded terrible. It gets more audible with the more revs that are applied.

[stamford]

When did it last have a decent oil change? Could be a noisey cam lifter not getting sufficient oil?