Outboard Oil Change & Lower Unit Mx Tips

bloody salt n00b

Almost A Member
Sep 14, 2014
The Greater Los Angeles
Boat Name
Triumph 195 CC
I previously posted asking where I can do my engine maintenance. My biggest constraint is living in an apartment, though with a one-car, detached garage, where my boat is too large to do any maintenance. My boat is kept dry storage where I also cannot do any wet maintenance. Recently I completed my first four-stroke engine outboard maintenance, which was a 300 hour interval, completing everything identified by the factory service manual. Here I cover important points from my learning that I hope will help you in saving time and money. For me, zerk fitting lubrication, anodes (including cylinder), shifter, spark plugs, etc. (all the other items called for in the manual), were straight forward, and I do not cover them here.

For the basic oil change, I used a manual oil pump from West Marine. I happened to see Erik Landesfeind using this type of pump back in November or December, because I watch all his videos, and saw how clean it makes the process (link below). Surprisingly in this case, West Marine has a competitive price on the 6.9L pump that is a copy of name brand pump. Wait for sales and use the rewards program and West Marine is not always the Worst Marine I've read it to be.

Now on to my main four tips for the BD community to summarize my reading and experience in servicing my Yamaha F115 lower unit. I just now happened to read Erik's article just now, and not before I did my lower unit maintenance. For some reason, I have never kept up with the main page and articles on BD, and that is a shame on me: https://www.bdoutdoors.com/outboard-maintenance-lower-unit-service/

I agree with Erik's sentiment. Try it out; it's not rocket science, and you'll save yourself a boatload of moola! As a fan of proper fastener torques, I recommend the factory service manual. It will also specify special tools and materials (e.g. sealants, one-time use gaskets, etc.). What I struggled in finding at first, and what I was used to from my motorcycling career, was a proper parts fiche. I found Crowley covered my motor and surprised me with excellent prices and shipping.

1. A place to park your lower unit.

I originally read about the Black & Decker Workmate benches on THT. Then I shopped for them, and no local stores that I could find carried the smallest version. Sure, I could order them... But I saved a few bucks up front by going to HFT and getting its copy...the US General Folding and Clamping Workbench for $20. You have to assemble, and the pilot holes were not correctly aligned originally, but I had to drill new pilot holes anyway to space out one side (not the side with the spinning handles, otherwise you block them from spinning), to accommodate the width of the lower's prop housing.

Use B&D Workmates seem to come as a good deal, if one happens to show up within your area. They appear that the bench planks have a greater width the open up to, so you don't have to do any "custom" drilling. I also noticed more examples of the heavier-duty model Workmates for sale used.​

2. That damned woodruff/impeller key.

There is lots of advice on drilling or using a small, rotary cutoff wheel to cut a slot. Based on my experience, the best method is to use a suitable, blunt object that will not bend with force, such as a pin punch (not a cheap one) or a ground-down chisel. Then, laterally and radially to the drive shaft, with a sideways motion, hit the bottom of the key. Then vertically hit downward on the top of the key. Repeat as necessary. You are essentially forcefully rocking the key out. This is much cleaner as compared to the metal debris left by drilling or cutting, and, as long as you perform regular maintenance, takes less time.

Alternatively, I read someone who recommended, if you have it available, to use an air hammer. You know, the type used for rivets and such, but with a chisel tool, and to just knock the key out from the top. I know this would be very effective, but since I don't have air tools, I had to work harder and not smarter.​

3. Inspect and replace as required.​

My brother-in-law told me recently that his dealer told him he "has to" replace the full water pump assembly every 100 hours on his newer Yamaha F200 outboard. He is in Florida and the boat is a salt boat, but kept on a lift (what a dream!). But I can't imagine that requiring the automatic and full-replacement of the water pump every 100 hours, especially at dealer labor rates. The service manual states to inspect and replace as required.

In fact, when I took my pump apart, the impeller itself was still supple with no noticeable wear. I did not replace it. The housing gasket I did replace, as the it is a one-time use part. Removing the impeller key damaged it, which required its replacement. The main o-ring had a set to it, so I replaced it (I am surprised the manual doesn't show it as a one-time use item). I also replaced the "collar" (read the manual/fiche) since it had wear from directly interfacing with the drive shaft. I bought a full-kit assembly of replacement parts. Now I have many extra replacements to use in the future, including the main housing.​


If you are doing this yourself, especially with a larger lower unit, use a ratchet strap to help. I didn't see this tip until after I did the job, but (luckily?) for me, I only have a F115. After lubricating the drive shaft, in reinstallation, the lower did not just "hang there" as compared to when pulling it out.

There are three, more challenging, aspects when reinstalling your lower unit.

A. Getting the lower up to the right height to plug the speedo water tube back in. Have a zip tie ready and hanging on the tube.

B. Aligning the main drive shaft. Put your throttle in forward. Ensure your gear box is in forward by rotating the gear box shift spline clockwise (looking top-down) for standard rotation models (counter-clockwise for counter-rotation models). It will still take some shaking, but just slightly rotate the prop forward (clockwise looking from the aft) in small increments until the drive shaft aligns to mate up with the head.

C. Let the lower drop back down just far enough to align the mating splines of the shifting mechanism.​
This is honestly the most complex part of the four tips, and I wished I had watched Dangar to help before I had to figured it out on my own:

Alright, I'm tired of the jokes here. Peace.

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Brawndo the thirst mutilator
Sep 18, 2004
Boat Name
I like the strap idea - it is easier than yelling for my family to come out and help.

Thanks for the video link.
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