I read the sticky on winterizing, and decided it was simple enough to do my own winterizing. What I couldn't find, was a decent diagram of where the drain plugs are located. Even in my shop-manual, it's kinda hard to tell from a B&W cartoon. They are pretty easy to spot once you know what you're looking for, but I'll save some of you the hassle of searching by posting some pics
This thread is just to cover the drain plug locations on a 1996 Mercruiser 5.7L (raw water cooled), but I assume that other year 5.7L, and most 5.0L Mercruisers have pretty much the same thing.
As you can see, not all boats have a conveniently visible blue plastic plug. Mine has brass bushings with smaller brass plugs in the block, and a black plastic plug in the exhaust riser. Never mind the jury-rigged street elbow + pipe nipple on the port side. It's obviously custom for increased horsepower and speed.
Also, remember to use a wire or something to poke in the holes as it's draining. My block drains were just sort of trickling out until I poked in there with some welding-wire. A bunch of mud globbed out then the water drained more freely at about 10x the flowrate.
I also had to remove the hose from the power steering cooler. I didn't see (or feel) a drain fitting on the cooler, so I just pulled the hose off the low end.
All in all, I drain about 2 gallons out of my engine.
I read in another forum post somewhere that some people get up to 5 gallons. Not sure how to get any more, unless I missed a drain plug. I just had it running with the hose and muffs yesterday too when I did the fogging oil, so it didn't drain out from being un-level.
Also, on a final note: should I keep the plugs out over winter? Logic says it's not necessary, but I put them in a ziplock baggie anyway.