Re: Merc 3.0 Engine Block Drain Plugs Location?
Reach under the manifold and feel around, should be on the back half of the manifold, on the underside. There should also be a drain on the elbow/riser, port side. Then the block drain you found. The drains could have threaded plugs in them, instead of petcocks.
As has been said many times, the drain holes can get clogged with debris and it's best to probe around in the hole with a piece of stiff wire to get the gunk out, easy to do with plugs, can't do it with petcocks. I have petcocks on my engine and run them open/closed several times to clear the junk out, sometimes need to remove the petcock to get the big pieces of junk out.
