So for a while I've had this annoying knocking noise coming from the.. valve cover area? It almost sounds like rod knock and only occurs at exactly 750rpms idling.

Any ideas of what this could be? See video for a better idea:

http://s6.photobucket.com/albums/y20...rent=knock.flv

 

Also everything runs fine and there is never any loss of power..

 

deifnetly doesn't sound like round knock.. before you continue driving it i would take off the valve cover and have a look around for anything broken or loose though..

it could be something small broken or loose and driving around could cause it to get stuck somewhere in some moving parts and end up making something small expensive.

 

I'll be taking that off tomorrow when my plugs, vcg's and plug wires arrive.

Also I've been driving it like this forever and nothings really changed.

Any ideas of what to look for?

 

best way to find out is to take the cover off n record again =]

 

Is it safe to run with the valve cover off?

 

Is it gonna spray oil or anything lol

 

Sounds like one of the cam pullys is hitting the cover. That or the belt is stretched to the point that it also is hitting the cover. Either way you do not want to drive the car till you find the problem....

 

crazy, i agree with LAST post...almost sounds like debris in there, but you have the cover on.
please update thread with what u find

 

definetly don't start it up with the valve cover off, it really won't hurt anything but it will make a huge mess, oil will splash around everywhere.

hopefully you'll see what's causing the problem, i agree though it sounds like it's coming from your timing belt/cam gears area.

 

Pull the cam gear cover and check your belt tension. Also check your clutch fan bolts are tight. Might be hitting the shroud.

Sounds like something loose and contacting plastic to me. Not a rod knock, no worries. At worst you'll need a timing belt.

 

I agree, it sounds like the fan may be grazing the shroud..... One of the 2 could be loose.

 

I'll try that out - where are the clutch fan bolts?

 

I took the cam gear cover off to find some black powder (almost like rubber?) on the inside of the cover itself. The knocking noise still continues..

One thing I saw was on the cam gears.. they seem to rotate a little of axis -- like a bent wheel on a balancing machine

 

^ Stop driving your car. The black powder that you speak of is probably your timing belt rubbing on something. Sounds like one of your cam gears is damaged and is altering the timing belts track. Or maybe your off balance cam gear is rubbing on the timing belt cover. You need to find your problem and fix it before you continue driving. Just take the cover off and inspect the inside of the cover carefully. If your timing belt breaks you will have bigger problems. Seeings your SC is a pre 98 without VVTi.