I have a 2002 100HP Yamaha 4 stroke.I fogged it(did not change oil or lower unit) and put it in the unheated garage in October.I just noticed a little oil on the floor below the prop.I think I would need to take the prop off to see where the oil is coming from.Is there a seal in there that might have gone bad by a freeze or something? I have never had the prop off since I bought it new. Any thoughts?
It may be just a little unburnt fuel/oil coming from the hub. I sometimes notice this after I store my rig after it sits a while.
Next time, might be best practice to change the lower unit oil in the Fall before it gets real cold.
I’d check the lower unit for water before you run it.
I always change my oil in the fall.
Could be ok, could be real bad.
Without seeing/being there we are all just guessing.
I would find someone who knows and can look at it to get the correct answer.
Lower unit oil smells rotten and is generally thick has a distinct Smell.motor oil would be blacker and would be normal as a little could easily blow by and end up in exhaust.your exhaust exits prop a little oil leaking out inside prop not a big deal. Oil leaks look big after spread out on floor.check levels and change lower unit oil then keep an eye on it
My guess is that is unburned fogging oil.
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My guess is that is unburned fogging oil.
x2
Sounds like fogging oil that drained through open exhaust valves. But check the lower unit oil first.
It is always a good idea to remove the prop at least once a season to check for fishing line or anything else that might have gotten behind the prop. If left there, line can get into the prop seal and ruin it releasing the gearcase oil. This is usually done at the end of the season when you change the gearcase oil. I have heard of people checking this after every trip, but seems overkill to me. You could try putting down some plastic and see if you can collect some of the leaking oil and compare it to your fogging oil.
If this is the first time you noticed oil on the floor under the lower unit, I’d say very high chance it’s fogging oil that went unburned out the exhaust and just took a while to work it’s way down and out the exhaust hub.
If your lower unit seals are bad enough to let gearcase lube leak out, you will very likely see A SIGNIFICANT AMOUNT of water in your lower unit lube when you drain and change it. A few drops of water is normal due to condensation, so don’t go nuts here. Bad seals are fairly obvious.
You should certainly change your oil and check for water in the spring. If you don’t know what to look for, drain the lower unit oil into a clean container and take it to a mechanic.
Replacing the lower unit seals isn’t terribly hard to do.
Grouse
Good info,thanks all. I normally change oils in the fall but this year got to cold on me and I just fogged it. I will change oil here in the next month hopefully and see whats up. Sounds like the fogging oil to me. Thanks all.
Agree it’s most likly exhaust residue. Nothing to worry about. Personally I don’t see a need to fog a 4 stroke motor.
-J.
Looks very closely and try to figure out where the oil is coming from. I have a small Honda that the lower unit leaks. As the water freezes it pushes the lower unit oil up through a shift linkage seal. From there the oil runs out a weep hole, runs down the skeg and drips. Like mentioned above lower unit oil and engine oil small very different to.
It won’t hurt to take the prop off and check the seal. I do this about twice a year just to check for fishing line. fishing line likes to tear up that seal
Mine always drool after I fog them.
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