checking the lower crank seal is relatively easy. mostly they are
installed in a housing screwed to the underside of the powerhead. a
small engine like yours disconnects easily(simple wiring, controls
etc) leave everything else on, carb, electrical etc and pull it all
off wholesale with the powerhead, turn it over and inspect the seal.
the lip should be sharp and the backing spring should be in position
and not corroded. you dont even need to buy genuine to replace it.
just have the exact measurements of the installed location and the
shaft diameter and any bearing/seal retailer can match it for you.
typically seals have 3 dimensions to order from the shelf. outside
diameter, inside diameter and width. take these to the seal store and
you should have joy. also check that the rankshaft area where the seal
runs isnt too "grooved" or corroded. speedi sleeves are readily
available to repair this location and easy to install. good luck.



"Mr Wizzard" wrote in message news:LVTed.241508$wV.188294@attbi_s54...
"Mr Wizzard" wrote in message
news:f2Fed.415363$mD.411619@attbi_s02...


Hey all! - just thought of a bit of information that I forgot to
add to all of this (which speaks to this lower crank seal bit).
Remember I said I had the reed box out a coupla times to
cheak/re-check, and in on post, I did say that I took out the
fuel pump diaphraghm to check it, right? - well, there is
something that I noticed that I thought was "odd", but just
didn't think too much about it. And this was the "black
deposit/stains in the lower crankcase. Mainly the well that
the fuel pump diaphraghm fits over. And looking into where
the reed box fits into, I can see a "little" into the lower crank
case. In both of these areas, I did see "blackish carbony
staining", more so in the little recess well on the side of the
lower crankcase for the fuel pump. To have "that" much
black carbon deposits/staining, there would HAVE to be
exhaust gases getting it, and circulating around this crank
case, right? I mean, I know that the fuel charge can cause
a light brown staining on crankcase components, expecially
around the scavanging ports and all, but "black" ?? So my
thoughts are this: (try to envision this). "IF", the lower
crankcase seal WAS badly leaking, the area BELOW the
crankshaft seal (free space in the intermeadiate housing)
IS positively charged with semi-presurized exhaust gas,
right? You have positive exhaust gas pressure in the open
area in the leg housing, because on these old motors (at
least this one), the "water ****er" holes are just that - "holes"
or slots in the housing (unlike the newer engines that tap
off of the water jacket up on the exhaust cover plate etc.)
So!.... if the open area in the intermeadiate housing below
the lower crankshaft seal is slightly presurized like this, AND
smokey/sooty as hell (like this engine appears to be running),
even the slightest vacuum in the crankcase (upward piston
stroke), coupled with an already smokey/sooty presurized
lower area on the other side of the seal, a badly leaking
lower crank seal would SURELY be letting smokey/sooty
gas INto the lower crankcase, explaining the black staining
in the areas of hte lower crankcase that I can see, PLUS
all of that wet black/fluffy black on the plug after just a few
minutes of run time - the upper cylinder is compressing,
and trying to ignite a charge that is already re-charged
with exhaust gas that us excaping into the crankcase.
So yeah, I guess I just talked my way thru this, and it all
makes perfect sense now. Dam, so got decisions to make.
Eat the $100, or bust out the cutting torch and get in heavy
iron worker mode. Thanks all for helping me thru this.







Got an old Monkey Wards Sea King .7.5 by Chrysler, and I am stumped.
It won't run on the bottom cylinder, not matter what I do. So far, I've :

changed the head, head gasket, coil, converted to electronic ignition,
went over the carb (twice), two new sets of plugs, looked at the reed
valves, and it STILL won't run regularly on that bottom cylinder. Runs
fine on the top cylinder, and every now and then you hear I occasionally
hear it pop and shutter, and hear it kick in, but for the most part, the
bottom cylinder won't run. Plug just black, sometime fluffy black,
sometime wet black. I even looked at the fuel pump diaphragm
under a magnifier glass, and it too looks fine. So what the heck
could I be missing here? Compression is at 150 Lbs. I just don't
get it. The only thing I can think of is the bottom crankcase seal
is bad, and I'm sucking in air or water or something. I even took
off the exhaust manifold plate to make sure the exhaust port wasn't
plugged. Peeked in the exhaust port, and the edge of the piston
looks fine. Surely someone have the missing clue, help!!

Thanks !