We diagnosed the issues. Let’s try to do some fixes!
First off, a major mechanical issue. The lower is leaking oil, and that’s a bad thing. If the oil leaks out, the gears and bearings will not have lubrication and will wear out quickly. There is a good chance water is also getting in, and that causes corrosion.
The most common cause of an oil leak for something like this is bad or worn seals. The other potential cause is enough to scrap this motor; a cracked case. Fortunately that doesn’t appear to be the case, it seems to just be some bad seals.
Before starting this project I purchased both propeller shaft oil seals and replacement oil and pump to get the job done.
My first step was to drain the oil and see if any water has gotten in. Plus, who knows when this thing last got an oil change? It should be an annual event. Most of the oil was blackish blue, which I would expect. The last little bit of oil to come out was milky colored and that indicates some water is getting in.
To drain the oil, the first step is to open the fill / drain cap on the bottom of the lower, then open the vent cap on the side of the lower. Be sure to have a pan under the lower to collect the stinky 90 weight oil. This stuff is thick, so will take a while for it to drain. Give it plenty of time. I waited an hour to let it all out. You may also want to change the angle of the motor so the fill / drain hole is at the very bottom.
This video is after I had loosened the drain and vent plugs.
The vent cap was relatively easy to get off. The fill cap had the screwdriver slot so stripped that I had to really exert some pressure to try to get it out. There may have been some swearing at the previous owners.
To fill, it is opposite of what you would think. You remove the vent cap and the fill cap and connect filler hose to the fill point on the bottom of the lower. You then pump in the 90 weight oil from the bottom up and stop when the oil reaches the vent hole. There might be an air bubble or two, so let them bubble out. It is full when a stream of oil leaks out. Clean up the mess and put the vent cap back in first. Then quickly disconnect the filler hose from the fill hole, and cap it.
I added a new drain/fill cap to the shopping list. It is a cheap part on Amazon. It was a quick swap later.
My next step was to take the propeller off. I did this with a piece of firewood and an appropriate socket and breaker bar. Ok, too hillbilly for you?
Fine. I used a screwdriver to carefully bend the ears of the retaining washer to allow the prop nut to spin. Then I tried to find something to hold the prop so I could turn the prop nut. One of the YouTube videos I watched suggested using a piece of wood, such as a 2 x 4. They also said you could use a piece of firewood in a pinch, say if we’re doing this at a marina or in the woods.
I saw a nothing obviously wrong with the outer seal. No damage. I’d have to pull both seals anyway to be sure.
Well, how do you get the seals out? The repair manual says you use a special tool to pull the entire bearing carrier out from the lower unit. This way you can work on the seals on a bench without the prop shaft being in the way. I don’t own that tool and I’m not spending the $100+ to buy one. Yes, it could be done with simple tools and some field engineering. I wasn’t sure I’d get it back together once I got it out.
I found this video here. If you can get around the throat and mouth sounds in the recording, it is very good information. Dangar Marine knows what he’s talking about. He got into my head “don’t knick the prop shaft”. His other videos are as educational.
I also read in the comments, that you could drill a small hole into the seal and use a slide hammer to pop them out. I don’t own a slide hammer, so I figured a trip over to Harbor Fright would be appropriate to get one.
I had mentioned my need of a slide hammer to my father-in-law and he said “Why would you go buy one when you can just use mine?”. The next day I went over and got it from him.
I picked up an appropriate drill bit to match the machine screw I was going to use with the slide hammer. I carefully drilled the hole into the outer seal, being very careful not to nick the prop Shaft or the bearing case.
I stuck the machine screw through the end of the slide hammer and used a screwdriver to turn it into the seal. I then connected the end of the slide hammer to the shaft and gave it a few pops to get the seal out.
The screw stripped out of the seal. I drilled another hole and tried it again. This time the seal came out on the first pull. I was elated I had not damaged anything in the process.
I looked down into the area between the seals and found some thread-like material. It was yellowed old fishing line. I think we found the cause of the problem!
The inner seal was a bit harder to go because it was further down into the bearing carrier. I drilled the hole and screwed in the machine screw and it also stripped out on the first slide of the hammer. I had to drill another hole and this time the screw held and it popped out with about three taps of the slide hammer. Again, I was happy I didn’t cause any damage.
Below the inner seal I found the problem. There was a melted together wad of old fishing line. Fishing line is the number one cause of propeller shaft seal failures. Below was between the oil seal and the outer bearing.
Here are the seals after I removed them. The one on the right destroyed itself as I removed it. It was the front seal, closest to the prop.
I next cleaned out the seal area. I got any bits of line that remained. I made sure the pop shaft was smooth, as well as were the seals touch the bearing carrier.
Time for the new seals. I put a little grease on the prop shaft and on the rubber part of the inner oil seal. I lined it up on the shaft, facing downward. This seal is meant to keep the oil in the lower. I also put a little sealant on the outside edge of the seal, just to make sure it didn’t leak between the seal and the bearing carrier.
I used a length of 1 1/4″ PVC water pipe to both protect the prop shaft and to reach the seal so I could hammer the seal into the carrier. This PVC pipe had the perfect outer dimension to fit down in the carrier amd engage the the metal part of the seal. I was able to get the seal seated firmly in short order.
Next is the outer seal, which is the water seal and faces outward, toward the prop. When I placed it up next to the bearing carrier, I noticed it was a little bigger than the inner seal. Multiple sources said this was the part number to use, so I started on this seal.
At first I used the PVC pipe, like before. No luck. I’d get a little of the edge into the carrier, then it would pop out. I tried whacking (gently) with a hammer on either side of the seal to get it started. Nope, and I put a little dent in the seal, but it still looked ok.
Time to regroup. I had run out of daylight anyway. I was not able to get back to the project for about a month. The weekends were busy getting ready for our vacation, and we used two weekends on that trip. I was not able to get back to this until early November.
But, during my time away from the project, I got some advice. My dad, who has been a mechanic since before his Army days, made a suggestion. Get some cast iron “black” pipe, same diameter as the PVC and give it a whack. The PVC has too much give and flex in it and may not be transferring enough pressure. “And don’t be gentle about it”. Ok.
I got an 8″ piece of iron pipe and a coupler for the end of it to spread out the load and provide a flatter face to the seal. I put the seal on the edge of the carrier, put the pipe over the prop shaft, and lined everything up. I got my small sledge hammer and gave it a good strong whack.
Part of the seal started! I re-positioned the black pipe to put a little extra pressure on the side still sticking up and give it another whack.
It popped the first side out. Well, huh. Ok. Tried it again.
Everything lined up….and WHACK!
One side went in, and that’s it. The seal twisted and deformed. I gave it couple more whacks and it popped out. Failure!
Well, that’s not going to work. Even if I get it in there, will it still seal? I’m guessing no.
So, I did a little research into it. The bearing carrier is 1.68 inches in diameter. The inner seal is 1.692 inches and is a tight fit, but that’s important for a seal. It was able to compress enough to fit and work right.
The suggested outer seal is 1.754 inches and that is too much to fit into 1.68 inch space. I’m wondering if somebody replaced the lower on this thing with another one, which has a different seal size.
For a temp/permanent solution, I got another inner oil seal and that one dropped right in using the PVC pipe method. I hope the inner seal is up to the task, but if it works, it works. It fit snug like the other one.
My helper approved and was happy to see it fixed.
I put the prop back on, which also uses the firewood method to keep the prop from spinning. I torqued the prop not down, and bent the little ears over to keep the nut from backing out. I pushed and pulled on the prop and it didn’t move.
Something had been bugging me for a while and it was due to a missing part. Boats often have sacrificial anodes to combat corrosion caused by water. It is a boat, and hence, often exposed to water. The anode’s job is to corrode rather than the rest of the metal on the boat. Anodes come in several metals, the most common being zinc or aluminum. Zinc is usually used for salt water. I decided to go with zinc as well, as it is common.
The anode on this motor doubles as a trim tab to allow you to adjust how strait the boat goes through the water. Sometimes the prop will push the boat sideways a bit, so you have to turn the motor in the opposite direction to compensate. The trim tab helps to cancel that and adds to the ruddering ability of the motor.
The bolt to hold the anode in place was still in the lower, so I just reused it. It threads down from above. I had to remove the add-on hydrofoil to do it. Two bolts on each side and it comes off and goes on easily.
That’s about all I could do to the bottom of the motor. It has fresh seals, a new anode, and has had the oil changed. I could have done the water pump, but it seems to be running OK right now. If I do end up doing the pump, there are some other seals to replace there, as well. Water pump means take the lower off and I’m not sure I’m ready for that.
I did some other work to the powerhead after I got the lower buttoned up, but that’s another post.