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1993 johnson 120 v4 , oil in test tank ? question

R

robert_kelly

Member
Recently replaced the VRO pump and using 50:1 mix plus the VRO. The test tank has oil in the water. Is it from the crankcase exhaust or a leaking crankshaft bottom seal. The oil is black and sooty like exhaust. The outboard is 17 years used.

The lower unit has new prop shaft seals .
 
What brand oil has been used in this engine? I would De-carbonize the engine with a can of Sea Foam. Get the engine up to temp, remove the spark plugs and pour a quart (8oz in each Cylinder) in the plug holes and let it sit for at least 24 hours. After the 24 hour period is over reinstall the plugs and run the engine. This will clean any build up out of the engine, especially if cheap oil was used.
 
could the oil in the test tank water be from the gas/oil mix from the crankcase leaking out of the seal, like a rear main seal on a car engine? , and carbon build up from the pistons with the unburnt mix exhausted.?
 
What you are observing is the reason why 2-strokes are banned in most lakes.
Just a small portion of the oil is actually burned, the rest goes out with the exhaust into the water.
You are, due to little volume in the test tank compared to a lake, getting a concentrated version of reality!
 
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