Most likely, gaskets perhaps with warped components that the gasket is supposed to seal--manifold to head, head to block, timing cover to block, etc.
Could be cracked casting(s)--heads, block, timing cover, intake manifold.
Could be corroded timing cover.
If you yank out the plugs, and one looks steam-cleaned, you'll have an idea where the problem is. Otherwise..."good luck" with the examination.
|