Originally Posted by Diesel911

For sure something gets oil to the Vacuum Pump. If you run without the vacuum pump it will likely be a mess but you can do it long enough to maybe find out where the noise is coming from.

I had a rattling noise coming out near the timing chain and gear as it turned out to be the upper most timing chain guide rattling. Tightening it fixed it.

Below that guide is an idler Gear but no one has ever posted issues caused by it that I have seen.

Don't know what the other timing chain guide rails can cause if there is a problem.

Way down at the bottom on the Oil Pump Chain Tensioner there is a little snap ring that people have said wears through and when that happens it can ever jam things up down there.

People have replaced timing chains with other the IWIS/jWIS Chains and had issues. Or I suppose someone could have changed the chain and not done a good job of it.
Remover the valve cover and check the make of the chain and have someone roll the engine by hand and observe the chain rivets and gear teeth for something abnormal.

Look at that camshaft and the bearing towers for something unusual.

Not sure how you would tell this but there has been at least 2 cases where people had cracked valve guides.

If you have a Federal W123 the Air Filter Housing is noted for beating on the intake manifold due to various reasons. It happened to me and I thought that something was going to fall off of the car.