Currently I am actively working on a 1947 Mercury KD3S in the basement and a
1941 Mercury KB3 in garage. Today it was 97F in garage and a cooler much
less humid in basement so naturally I worked mostly on KB3 in garage...
despite best efforts piston is still stuck in cylinder and Wico flywheel
is still stuck on crankshaft. I did manage to work lower cover off to get
a look at crankshaft journal and connecting rod. For some reason I seldom
find as much corrosion on prewar crankshafts as on postwar crankshafts.

Down in the basement the rewind starter struggle continued. Finally took the
spring up to garage to heat and rebend loop. That went well. Returned to
basement and after a number of trials found the right number of turns to
preload starter tension. Fastened handle on cord and gave it a number of pulls
which seem to indicate A1

Gave myself the rest of the day off.

About the only things holding up KD3S now are gaskets and seals. A funny thing
about these singles is that both have the same new to me riveted loops on
ends of starter rewind springs. I decided to heat and bend after comparing
the two springs. Heating spring leaves it relatively soft and pliable so it
can be reshaped. In the future I will try tempering in an oil bath. I have several spare springs needing hooks on ends so maybe more to report later.
Louis

Progress report on 1941/42 Mercury KB3. Used grease gun technique to press
piston down cylinder until grease leaked. Went pretty easily so PB Blaster
may have done some good on cylinder wall. After considering options pounded
on piston with WOOD dowel thru spark plug opening...more in hope than conviction BUT it worked! Removed "G" clips and piston rings and pushed piston pin out and removed piston. Screwed a threaded brass cylinder on to chankshaft
with just a small gap between brass and flywheel so crankshaft could be pressed down thru the flywheel hub....a new to me and risky technique....all went well on first press and successive pressing as brass protector went down a little
I released press and turned the brass up the thread of crankshaft...after
about 3 repeats there was a LOUD bang. That could have meant bad news like
a crushed crankcase but I was lucky...the flywheel was loose and nothing was
broken.
Boxed up parts and set things away. I used up my quota of luck for today.
Words have their place but it would be easier to explain with a couple pictures Taking a stuck project motor apart can be a contest between haste and patience.
Experience has taught me patience ruins fewer parts. I have the advantage of
some Mercury Service Tools, some tools I have made and a few tools an expert
made for me. I have also had the advantage of expert advice and encouragement
from friends in outboard club. For me there is nothing as enjoyable as taking
apart an older Kiekhaefer that someone consigned to junk pile decades ago and
bringing it back to life. No two projects are exactly alike and some will turn out better than others. They are all fun.

Louis

Today hot and humid so downstairs was the place to be working on KD3S.
Note: tearing down and rebuilding two motors at same time is not a good idea
but temptation is hard to resist.
I got out gasket cutting tools, gasket stock and old gaskets to use as patterns
then cut enough gaskets to assemble both powerheads. Pretty much routine
and it went quickly. No news there.

Now the real news...it is not uncommon to find the lower end of drive shaft
seal surface pretty rough and/or the original seal either missing or in tatters. It is possible to use a metal case lip seal but if drive shaft is
rough or uneven seal is of little use. Granted the gear case is packed with
grease so not much sealing is required. I have given the subject some thought
and today with all the tools at hand and some leather scraps a few experiments were tried.
I used a 3/8 punch and a 7/8" punch which seem to be good fits
on 1/2" shaft in the 3/4" pocket. Free hand punching would not locate 3/8"
hole concentric to the 7/8" disk of leather. The idea was right but the execution left a lot to be desired. Then the little gray cells kicked in...
using a scrap of maple, a 3/8" rod and a washer with a 3/8" center hole
that was slightly less than 7/8" outside diameter a tool was made.
a) drilled hole in maple to accept 3/8" rod
b) inserted rod
c) punched 3/8" hole in leather scrap
d) placed scrap on 3/8" rod
e) placed washer on rod over leather
f) placed 7/8" punch over washer and punched out a leather seal
Essentially what I have made is a flat leather washer that takes on a
cup shape when in place under the spring. Cleaning up drive shaft
and applying JB Weld and sanding it smooth is next on agenda. There
probably is something better to use in this application but using what
is on hand is a time and money issue. I doubt motor will get enough
use to make wear an issue.

The drive shaft on Kiekhaefer's early K Models uses a spring to retain
leather washer and a spacer to compress spring and align the gear case
to drive shaft/exhaust housing. I have taken apart quite a number of early K Models both prewar and post war. It seems the rule that prewar motors have
less corrosion of both crank shaft and drive shaft. Why this is I have not
a clue.
Louis

Sometimes the results you want come with results you do not want. In July 16
comments I described how I removed stubborn Wico cast zinc flywheel from crankshaft of KB3. Flywheel did come off and there was no apparent damage...
but now the rest of the story. Yesterday I worked on stubborn rod cap screws
finally they released their grip and rod was removed allowing crankshaft to
be taken out of crankcase. Powerhead now fully apart for cleanup. Crankshaft
as usual for a prewar motor was not deeply pitted. After polish with fine wet
or dry I did a trial assembly of crankcase, crankshaft and lower cover. To my
surprise the assembly locked up. I did not think it was the crankshaft as it
had turned freely before flywheel had been removed. Today a test fit with
a known good crankshaft also locked and the KB3 crankshaft fitted and turned freely in another crankcase. A careful examination of the crankcase of
KB3 revealed no crack,distortion or unevenness.

While the press did remove a very stubborn flywheel and the damage to crankcase
was not immediately apparent it did ruin the crankcase. Not a project ending
just a readjustment. Another project will have to give up its parts to make
the KB3 and another project move ahead. The unusable crankcase resulted from
wishful thinking and a short cut approach. Not the first time I have learned
the hard way.
Louis

Last few days have been both hot and humid by SE Michigan standards so a bit
of progress on both Mercury KD3S and KB3 to report.

Finished stripping down KB3 and figured out a way to use later pawls in
early starter rewind. All parts are pretty grimy so much cleaning ahead.

Honed replacement cylinder for KD3S, fitted rings and assembled powerhead.
The daylight at end of tunnel is getting brighter. This project will still
lack cowl and spark plug cover but only required 3 new rings a top crankshaft
seal and the block to leg gaskets (other gaskets were made from gasket stock)
Cleaning supplies and paint a given for an old merc. Other than misplacing prop nut nothing out of ordinary. It remains to be seen if coil is as good as it looks.New rings and hone resulted in solid compression.

KB3 project does not appear to have any unresolved problems except replacement powerhead did not get a full tear down.
May have to take another look inside as it may be called upon to run.

One new bit of knowledge...lower drive shaft leather seal is not hard to
make and look to be as good as original seal was when new.

If ANYONE is working on an Early Mercury K Model or has a toughie to work
on PLEASE feel free to join discussion. If there is any way another "Little
Old Merc" can be revived count me in.
Louis