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1966 Johnson 20hp - holes in lower unit?

T

TimMSU

New member
I'm in the process of rebuilding a Johnson 1966 20hp FD-20 and noticed the other day there are some small holes in my lower unit, one is leaking a little bit of oil. I read thru a few old service manuals and nothing seams to speak of these holes. I have a parts motor and it too has a mystery hole... Should I be worried about these? Plug them?
 
DO NOT PLUG these holes !!-----They are there to drain water so that the casting does not freeze in cold climates.----Make sure they are not plugged with sand and mud as that is very common.
 
If it is gear oil then yes.----Often you will find oil leaking there that came right through the engine with fuel.----------To determine whether the lower unit has a leak you pressure test.-----After the lower unit has been apart for any work then a pressure test is recommended to check your work.----If you decide to reseal then do not overlook the o-ring on the shift rod as it is a very common leak point !
 
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