OWNER Of 1999 Yamaha 2 stroke 115 - Water In LU

Hurleyg

Recruit
Joined
Jun 2, 2016
Messages
4
I'm the new owner of a 1999 Yamaha 2 stroke 115. I drained the oil in the lower unit today and it came out milky white. I pulled the prop looking for fishing line or rope and found none. I'm reluctant to assume the oil is just old instead of water intrusion. I wasn't looking for water when I removed the lower plug so not sure any water came out first. Suggestions?
 

robert graham

Admiral
Joined
Apr 16, 2009
Messages
6,908
Not knowing how long since the oil was last changed, maybe refill with fresh oil and run the motor a while and continue checking for water....new washers on drain and vent plugs. If later checks indicate a water/seal leak then a pressure test on lower unit will help identify which seal is leaking....
 

99yam40

Fleet Admiral
Joined
Sep 7, 2008
Messages
8,851
why not just pressure check now that you have it drained to see if it leaks and where
 

ClassicAQ

Petty Officer 3rd Class
Joined
Jun 2, 2017
Messages
78
I'm not 100% positive, but pretty confident, that if you're gear oil is milky white it's because and only because water has passed by the seals and infiltrated the gear box. Essentially, regardless of how old the gear oil might be, it's color will never turn milky white because of age. It turns milky white only because it's come into contact with H2O.

I don't see any issue with r. graham or 99yam's suggestions. If you don't have the necessary tools to pressure test, go with r. graham's suggestion and refill with new gear oil. Run engine under load. Drain oil. If the new gear oil is milky white....replace seals.
 

Hurleyg

Recruit
Joined
Jun 2, 2016
Messages
4
Thanks for all the inputs. I don't have access to pressure tester so have decided to take it to a certified mechanic. At least you all confirmed it to be water intrusion and I have a leak somewhere in the unit.
 

QBhoy

Fleet Admiral
Joined
Mar 10, 2016
Messages
8,286
Quite likely it?s just the seals at the vent and drain screw. I?d be tempted to replace both with fresh oil and see how she goes.
 

tommarvin

Ensign
Joined
Nov 22, 2015
Messages
999
You can get a pressure /vacuum tester at harbor freight tools cheap, then you can test at the end of every season, for the rest of your boating life.
You can use 100% synthetic marine gear lube that's tested with 10% water and it passes independent third party strict testing..
 
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