Re: Trash talk on the 470/3.7l
I was "
that guy" that trash talked the 470 in the other thread. (albeit with some mistakes made by me.)
The long and short of it is, in the entire history of IO motors, the 470 ranks right down there at the bottom, right with the very old renaults and the very old 2stroke powerheads mounted as an IO. The latter technologies where when IO boating was in it's infancy, where as the by the time the 470 came about in the 80's there were then, which are still available today, much better choices for engines.
Sure some people have had luck, but a good portion also did not. There have been many a boat owner over the years that shelled out thousands maintaining and repairing that motor only to have a complete, total loss disaster a short time later.
It's not mechanics fault, and sometimes not even the owners fault, it was just a poorly designed motor from the get go.
All boat engines are basically abused in the worst possible enviorment. The Merc engines of today are designed to handle that abuse and then some. The 470 was designed to be used, but not abused.
That's just the engine however. Another thing to note is pretty much any boat made in the 1980's was made like carp. Many boats builders simply did not follow Mercruisers instructions to vent the engine box so the ambient air temperature stayed below a certain temperature. How many of you old timers here have run across hulls that the driveline simple was not centered in the hull, Or the antiventalation plate was to high or to low?
Check out this thread.
http://forums.iboats.com/showthread.php?t=366529
In it you will see a picture of an open deck block.
In a closed deck block, if you have a compression leak it either leaks internally to another cylinder (which is simple enough to diagnose, and really doesn't hurt anything long term) or it leaks externally, out the side of the block, and you can see it, hear it, and feel it.
On an open deck block, if you have a compression leak it almost always leaks into the cooling system. The cooling water gets displaced by air. That air then surrounds the cylinder until the cylinder gets red hot, goes out of round, and whammo. Total loss. And the kicker is, if it's a small leak the engine still makes plenty of power so you don't know anythings wrong. If it's a big leak, most boat owners have this thing about running engines until they break instead of taking it in for service the minute they sense anything is wrong.
If you look at the picture you'll see that a $50 head gasket failed, and cost me a $5,000 motor. That engine in particular never had any kind of overheat in the 55K miles I put on it. The gasket just failed.
And to add to Don, you can pretty much run most GM V block very hot and not have head gasket problems. The little 3.0L with run close to nuclear fusion hot before it cooks completely.
,dont care who ya are !
