Vintage Sears Garden Tractors
Crankshaft Seal and O-ring On Flywheel Side
This particular project started out as an investigation as to why the engine was cutting out when it was at full operational temperature.
The first thing I did was to degrease the outside of the engine. Once I did this, there was no spark any more. Not a problem, I'll just
leave it out in the sun to dry, then it will start......wrong, still no spark two days later. I figured the ignition was the problem to begin
with, so this just gave me good reason to tear it down. I have another magneto assembly and a NOS coil to mount, so it is really no big
deal. What I found going on under the flywheel was not expected.
I won't go over flywheel removal again, but will only mention that this one gave me a
little trouble coming off. I don't think it had ever been off before. Once off, I found
that there was considerable oil leakage coming from the seal and O-ring under the
bearing boss. It was easy to remove all the rest of the parts to get to the seal, probably
because of the amount of oil all over everything. It's a good idea to check the crank for
any rough areas before installing a new seal so that you don't tear the seal when
installing it. The crank end play is set by thin washers under the bearing boss, so don't
lose these. The seal has to be set all the way down to the bottom of the boss, or else
there will be a problem with the clearance.
Here's another problem I think was related to the bad seal and O-ring. This engine
had been running hot. Hotter than normal. The exhaust valve area of the engine had
even discolored white. When I found the seal and O-ring for the bearing was bad, I
noticed that the oil had been thrown everywhere. This had caused dust to collect all
over the engine.  There are cooling fins on the area around valves. The exhaust valve
is on the far side of the engine, so Tecumseh made the fins for it larger so as to catch
more cooling air. There is a passage way for the air to travel to the exhaust valve that
was plugged with the oil/dust grunge. See the picture on the right to understand what
I'm talking about.  I'm sure it will run cooler now that the debris is cleaned out.
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All written material © 2000 VSGT