Hi michael bethke,
If it is the oil pump failing, the oil pressure indicator would light up. To confirm if that is the cause, get the oil pressure checked.
Remove the valve cover tyo inspect the rocker arms and cam carriers. If there is a lot of sludge caking ( usually due to use of oil treatments ) on the components, most likely the oil passage is clogged somewhere. This woud cause wear on the rockers and the insufficient oil passing through would result in the rattling.
Sunday, August 8th, 2010 AT 1:46 AM