I have a 25hp 4-stroke Merc and I had a dealer perform a gear lube change in the spring. I just winterized the motor myself and drained the gear lube. I have heard that milky lube means you have a water leak. I’m thinking I have a leak (see attached pic). I’m wondering if anyone else can weight in on whether I have a leak and need to have the seals replaced or if this is what gear lube normally looks like after one season.
thanks much,
JP
Yep… That looks like water has mixed in. If you put it in a clear jar, it should technically separate (I believe) which would confirm.
Long time no see, Jason! 
The usual (and cheapest) culprit is the screw seals themselves. If the dealer did not put new ones on the screws, you are asking for problems.
I would buy new ones and install them, then run it around a bit on the lake and check your LU oil again. If it isn’t milky this time, you identified the problem. If it is still milky, you might have a more serious problem.
Keep us posted!
X2 on the drain plug gasket.
Had the same issue, new gasket.problem solved.
Hopefully it’s no more than $.50 gasket.
Good Luck
Best thing to do is pressure test it. I made my own pressure tester for a few bucks from stuff at fleet farm. I have it written down at home the pressure and time that it should hold it for, that comes straight from the service manual.
Anyone know what the he!! He’s ^ talking about? 
My biggest concern is why are you letting a “stealership” do this when you can do it cheaper and better… Try some top shelf gear lube like royal purple or amzoil with the money you save…
I had the same thing with a 60 hp Yamaha, just like Pete said put new seals on your Lu screws with any luck problem solved 
You are supposed to pressure test your lower unit to verify the integrity of your seals. The marine service centers that I know all do this especially after doing work on a lower to verify that it is sealed up.
All good shops pressure test there work
Good shop… hard to find… winterizing a huge money maker for boat places… never again for me… I wouldn’t go to any dealer unless something breaks… they see lower unit… and they see one thing… $$$$$ with bottles of marine gear lube readily available at most auto places… (online deals up to 40% off!) no reason we can’t change LU lube more frequently…
So what is needed to pressure test a lower unit? My 25 Honda consistently has a lower unit leak. Done the prop shaft seals twice and it still leaks. How much pressure do you test it with?
I will predict 2 outcomes by taking a motor to get the lower unit pressure checked…
1…. under warranty… “no sir no problem looks good… we replaced a few gaskets… that’ll be 90$…”
2….outa warranty… “Oh… you got some big problems… whole thing shot… that’ll be 1500$… boat will be ready in 6 weeks… ”
water sneaks into lower units all the time… check what ya can… replace gear lube more often!!! takes minutes!!! boating season only 6 months… change it every 6 weeks!!
Check Advanced auto parts website… 25% off and free shipping… get a bunch of quarts! I avoid any product that says “mercury” “honda” “evinrude” pennzoil seems to make a nice marine product… along with lucas… I myself just got 6 Qts of ROYAL PURPLE gear lube from AAP for 40% off and free shipping… (I use regular RP gear lube… see no use for marine grade since I change lube more often…)
if the motor is moving across the water… Don’t sweat it…
when it fails then break down and take it to the Stealership… FYI… It can be done by yourself… if you are handy…
A Stealership sees you as one thing when you walk through the doors… Giant Dollars signs…
DO EVERYTHING YOURSELF!!! money saved can be used for Beef and beer…
Thanks for the comments. I plan to replace the gaskets around the screws in the spring…they didn’t look that great when I pulled them…hopefully that does the trick. I love cheap fixes!
jp
Little early for winterizing you done for the year?? you got dings on prop?? Warranty??
I guess I don`t agree with Iceman taking a lower unit in to get checked when maybe all it needs is a seal versus continue to run and risk the chance of completely destroying the lower unit costing mega bucks, and the good possibility of getting stranded.
Did you check for any line wound around the prop shaft?
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Little early for winterizing you done for the year??
No kidding!! Some of the best fishing is coming up! Now lube up and get ready man! 
I’m with you hamm… labor day… football and hardcore fishin… right to thanksgiving day… winterize a 25hp?? unclamp it, put it in the basement… forget abaht it!!
i fished in an everstart years ago… hit a metal crab pot on the potomac… punched a 3 inch square hole in the lower unit… all the lube out… idled back to ramp… just water in it… went to evinrude trailer… no help from them… jerks… went to hotel… guy saw my problem… told him story… he thunk about it… looked around… said i’ll be back… came back with metal screen and duct tape… he patched it up with the screen and duct tape… filled with lube… ran it that way for 4 more days… no problem… up to 70 mph!! had my best finish ever in an everstart tourney…
I’ve had “pressure checks” done during the winterizing… My opinion, a bunch of guys back your boat in the garage, look at it… pull it out and winterizing done… 130$ please… next…
winterizing the biggest scam in the boat world…
you pay somebody to do this your crazy…
Don’t forget to take the prop off to check for fishing line
As others have mentioned, I would work through this yourself for a while first.
One of the keys here is how long has it been/how many hours of use since your last LU lube change? You may have anything from a very minor leak to a big leak depending on how long it took that water to get in there.
Here’s what I’d do:
1. Replace gaskets on LU lube ports.
2. Remove prop and check for fishing line on prop shaft.
3. Fill with lube and run it for a while. Like several sessions and 8-10 hours of actual in-water time.
4. Dump lube in a clean pan or better yet I like a big glass jar. Check for water.
What you do or don’t do next depends on if/how much water you find. You may fix the problem, partially fix the problem, or at least verify the size of the problem.
BTW, a leaking lower unit does NOT automatically mean a total high-dollar rebuild by a dealer. You can easily replace some of the seals yourself and if you have reasonable mechanical skills, you could do a total seal job yourself.
Grouse
Another question on gear lube, I replaced mine just the other night and today it appears that I have a very small drip going on. I inspected for any hairline cracks and can not see any unless they are so tiny the eye can not pick it up. A couple of you mentioned replacing the seals under the 2 screws, not sure if thats the problem but were would one find these seals or rings, any help would be appriciated.
Wahly
You probably just overfilled it slightly and then gear lube ran out between the threads of the plug before you managed to fully tighten it.
The other thing that happens is that the gear lube runs down the outside of the LU when you pull the drain plug, and then it “clings” someplace where you don’t see it and clean it up. Then it drips off later and appears to be a leak.
Either way, if you have a leak, it will leak all the time. Unless there’s a puddle of gear lube under your outboard, you probably don’t have a leak.
Grouse
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were would one find these seals or rings,
Any dealer has them, along with new plugs (also highly recommended).
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