Why Drain Your Lower Unit

11/20/10 @ 7:18 AM
ORIGINAL POST
thinblueline
thinblueline
USER since 1/25/10
Every year in late fall, I drain the lower units on my two outboard motors, which I dread doing because it always turns into a big stinking mess. Every time, the lower unit oil comes out looking the way it's supposed to, so I keep wondering why I'm doing this. Then I got to thinking, what about all the guys that fish the lower basin of Lake Michigan all winter in sub-freezing temps, even breaking or cutting ice at the ramps to get out, only to go home and store their boats outside or in unheated garages during those same, long sustained periods of sub-freezing temps until the next time they get out the next day, next week, or three weeks from then. Most of those guys just say lower your motors while still on the angle of the launch ramp, to let all the water run out, and you're safe. Well if that's the case, why don't all of us just do that on our last trip of fall, and not worry about the whole draining procedure? I've actually got a few friends who say they no longer mess with it for the same reasons I've questioned, and they never have any problems. Any comments on why other winter boaters don't have problems with their lower units, but mine might crack if I don't change the lube?

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Displaying 1 to 10 of 35 Posts
3/1/12 @ 7:48 AM
drummer boy
drummer boy
USER since 3/14/08
This is what I do in the fall every year,I take the prop off then I put the prop nut back on so I can turn the prop shaft.Then I put a dial indicator on the shaft,the shaft should be within a couple of thousand run out.Then I check the oil if it is not milky and is clear I do nothing.Seals last a long time on a shaft that runs true.But know matter what I do change the oil every three years.If I hit the prop during the fishing season I do the same thing CHECK the prop shaft.

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3/1/12 @ 6:44 AM
pugfishin
pugfishin
USER since 1/4/12
Oil is cheap, lower unit rebuilds are not. Besides, changing your gear oil and screw washers is part of a proper winterization. Also dont drain and leave empty, this allow oxygen in and rust on gears and bearings.

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2/29/12 @ 9:04 PM
Kevin_WI
Kevin_WI
USER since 12/28/10
This late fall I bought a boat/motor combo. was in good shape. Guy said he hadn't used the boat but once all summer...kept it inside, and he just changed the lower unit oil....so I got it home and checking it over.....let it set for a few days and I do another once around.....there is a small stain on the grass....it's lower unit oil....so I proceed to open the bottom plug....very little comes out....open the top....still very little comes out...but what does is clean as new.

Turns out the o ring must have fallen off the drain screw when he replaced the lower unit oil.....If I would have ran that engine, I would have fried my lower unit. I put a new o rign on, and lube in it in September and still checked checked it before I put it away for the winter. it takes like 10 minutes, tops for peace of mind.

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2/27/12 @ 3:46 PM
jusfishin
jusfishin
USER since 2/27/12
You have figured out what I have known for years. Suggestion. Pull to lower plug only. Drain any water out cause oil floats on water. If the oil looks clear and no dis-color oil or burnt smell is seen or smell, then plug it and add to the top. If you are going to use this practice, it is important to check more often.

I'm sure you will use some common sense on this. Motors aren't cheap. But you are right about the boys in the north.

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1/28/12 @ 8:38 AM
Wade B
Wade B
USER since 1/27/12
The simple answer is because the one time you don't you'll have water in there. We've cooked a lower unit once due to a bad shaft seal and not periodically checking the oil. Many thousands later we were back on the water. It's an expensive problem that can be avoided simply by checking/changing the lower unit oil.

Also if there is water in there over the winter it can freeze and crack the housing. Major problem there as well.

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1/5/12 @ 12:20 PM
eyeguy
eyeguy
USER since 6/26/01
Unless you look at the oil, you can't tell if you have water getting in from a bad seal. Bad seals happen. Would you want your motor sitting the winter with oil that looks like the attached picture? I knew the seal was bad so I changed the oil every other trip until I could get the seal changed. Imagine what it would look like after 10 trips. I would never go into winter without at least checking what the oil looked like.

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1/3/12 @ 8:06 AM
fuzzyfishin
fuzzyfishin
USER since 3/26/07
My grandfather and father preached to us growing up to drain and fill the lower when put to storage. Also the next spring would drain and refill again. Cheap insurance. Never with 4 motors did we ever have any problems with the lower units. They were stored unheated. I still do the same today. Although I never put it in storage, use mine all winter long if I can launch.

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12/28/11 @ 6:45 PM
haulin bass
haulin bass
USER since 4/8/07

I second what bigrock posted. You change the gear oil to make sure there is no water in it. Any moisture can ruin your seals and that costs alot more than gear lube. Drain it, refill it and you are good to go.

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12/26/11 @ 4:59 PM
cookiedough
cookiedough
USER since 5/1/11

I have changed by 40 hp 1997 4 cylinder yearly since new.  Never had water in the oil and looked near new each time draining it, but not perfect with the first time way back in 1997 some metal filings on the drain plug, not much though.  Never have ever replaced the o-ring washer ever since looked as good as new, but others replace that every 2-4 years or so.  I use my boat sparingly like 4-10 times each summer, so really not needed to do every year in my opinion.  If I was using it 15-25 times per year, then I can see changing gear lube once every year.  It is that one time that water comes out first that you will regret and then if that happens, replace the rubber o-ring for sure.  Cheap insurance with the bottle pump that threads onto the bottom plug, easy to do and cheap but not needed for me really every year, more like once every other year for low use like mine, but I do it anyways since easy and fog my engine by running it in a 32 gallon trash container filled with water in my yard and take cover off, let engine warm up fully, take a can of mercury spraying fog oil with red long wand attached and spray into the 2 carbs back and forth full spray and then disconnect gas line and keep spraying fogging oil back and forth into carbs both top and bottom one and rev engine a bit while doing this until you see a cloud of smoke rise up behind the engine until the engine eventually dies due to lack of gas and too much fogging oil.  Then, take out spark plugs (I have 4 for my 4 cylinder), clean the gunk buildup on plugshem with fine very tiny flat screwdriver, squirt a few sprays of fogging oil into the spark plug holes, turn over engine by hand cranking it on top a few times, and reinstall plugs, put cover back on and good to go all winter long.  I put so much fogging oil in that the oil runs out the prop on bottom and makes a mess without putting newspaper and cardboard on your garage floor once you lower the engine fully.

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12/23/11 @ 3:44 AM
Greyghost
Greyghost
USER since 6/24/01

I didnt drain last year and had to fix a broken lower unit this spring had some mosture in the oil DRAIN IT

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Displaying 1 to 10 of 35 Posts