To add to what simplyconnected said, if the vein plug was left out, and I am specifically talking about the one behind the timing gear, the top end will be starved for oil while the bottom end is getting oil. The bottom end would get oil pressure, but it would be compromised because of the open vein. It could be a very simple fix if that is the case. Cost= timing cover and water pump gasket and a pipe plug.
There is also a soft plug on the left side of the camshaft that could also be missing.
A lot of rebuilders pull those plugs to run a brush down those vein's to clean them, and sometimes they get over looked during assembly because they are so small and easy to miss.
Last edited by Larry : 02-10-2014 at 08:21 AM.
Reason: Add info