Sometimes cork gasket has a tendency to squish “out of place” if over tightened,
causing a leak. I think I’d try to find some non cork gasket material the same
thickness and a good gasket sealer.

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Harrison_Bergeron

Factory used thin gasket. A thick gasket will change gear lash.
Karropak 1/64″ or 1/32″ are in range of several replacement gasket
sets I measured.
The 3 slit type water pumps have an oil seal in the water pump
housing. I believe C/R 4923
The drive shaft seal is made from leather, a scrap of leather can be
used to make a replacement.
Cork is NOT suitable for this application and may do harm by upsetting
factory gear lash arrangements.
Karropak is suitable for sealing oil, gas, and coolant as well as water.
Louis
There are 3 ways for water to enter or grease to leave…likely all 3
could stand attention nearly 3/4 century afte KD4 left factory.

• This reply was modified 3 years, 9 months ago by green-thumbs.

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Harrison_Bergeron

The REALLY important things are 1) impeller 2) gear lash 3) grease
The lower unit water pump and gear case are well designed and easy to
understand. There have been several in depth threads relating to the
care and treatment. Low cost widely available impeller have been adapted to replace the tired old impeller.
Gear Lash…the gear contact is controlled by steel shims ahead of prop
shaft gear and a bronze spacer and steel shim above pinion gear
on drive shaft. If these are left out the gears will nosily chew each other
to pieces.
Grease…gears like to be lubed by this slippery slime…the plug in side
of gear case is often corroded in place. LEAVE it alone…pack grease
into gear case when water pump is off.
The water pump is secured to gear case by 2 screws with lock washers…under size heads and small diameter lock washers…they are
specific for this location,,,regular screws and lock washers will not fit.

You need to pay attention as you take the Early K Models apart AND
often find that a prior mechanic did not. Throwing all the fasteners
in one place will come back to haunt you when assembling as many
of the fasteners are fractions of an ench different in length to suit
different locations. Measure length of thread and size of head as
your remove and record for reference when putting things back together,
Louis

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Harrison_Bergeron