How A Lower Unit Fills Up With Water

[@crispernator]

Gday mate another great video with tips on what to do and where to look , ive seen a number of ways to get those prop seals out and although they seem fairly easy you have to be extreamly carfull as you said not to scratch that shaft take care .

[@kuang01]

more and more great content came up making the channel a boat mechanic library! thank you as always!🎉

[@cmetzenberg]

Just had milky oil. Shaft seals looked crummy. Watched one of your videos. Replaced seals. Pressure tested good

[@malekodesouza7255]

I had my lower on a Suzuki 150 leak. Tech told me it was the upper seal. He re-sealed the unit and so far, so good.

[@pauleskridge7209]

These seals are just like camshaft or cv shaft seals on a car. Thanks for this lesson on lower units. I needed to learn this as a new noat owmer and having to do service on my 1986 35 horse mercury engine.

[@rockhavenfarms7213]

Love from Durban South Africa bro. Keep up the videos as we have been using them as our "shop manual " since I found your Chanel back in 2019.

[@DrewHall-un8sn]

I'm impressed with your ability to say "shift shaft" without messing up. On the serious side you're doing great work. That lower unit looks a lot like my Nissan.

[@BornAgainBoating]

Thank you lol :)

[@mikencrew8885]

Man you are killing it with the videos. Love it!! ❤❤🎉🎉🎉🙌🙌🙌

[@howardparsons3371]

love the great content and information on the lower ends. Keep up the wonderful work.

[@CaptDavesSportfishing]

THAT BOAT is a treasure trove of youtube content for ya, huh? I wish I had room to buy/restore a ALUMINUM ole junker.

[@guyanesegamer1693]

I did one it was worth it

[@rockhavenfarms7213]

You know there's something t an old boat when someone with access to literal tens of boats at his disposal chooses to only play on the one.

[@CaptDavesSportfishing]

The one that he'll flip...duh yeah. ​@@rockhavenfarms7213

[@gregfeldman6818]

“THAT BOAT” is Lucky Aaron found her/him

[@frederic1000001]

Your experience is gold.

[@elcaptitancivil2860]

Great content. Thankyou for sharing

[@MrShreddick]

Unreal video and comments. Cheers boys

[@jamesyoung6829]

For a layperson like me these videos are fascinating but also scary when you think of all the components in an engine or lower unit that could fail at any time without warning! 😮

[@SniperViper198]

Hey born again boating. Here's a tip my dad taught me. He replaces theower unit springs in the oil seal with an o ring. Same on the trailer bearings. I haven't had to replace trailer bearings since 2004. So where saltwater touches we use an o ring instead of the spring. Remember tk use a slightly smaller o ring

[@gregfeldman6818]

Interesting! Great Comment. I’m a little afraid to experiment on customer jobs, but, may someday try it on one of my projects

[@BornAgainBoating]

Interesting! Never heard of that but I like it! :)

[@erichellstern542]

you can find the leak by draining the oil in the gear box. connect a air hose to the drain port at the bottom of the lower unit , then put 15lb of air pressure into the unit. With a bottle of soapy water you can spray the various seals to see where the air is escaping. I have done this and it works great. my shaft seal was leaking and made short work of finding the leak.

[@thurmondhomeinspections5946]

Hey Aaron. Love the channel. Always great content and have been a subscriber for some time. I’ve got a 2003 Yamaha 90 Tlr 2 stroke. I’m going to die on that simple 2 stroke hill. It Wasn’t circulating water so I rebuilt the water pump. Didn’t help. I had to go through the exhaust intake (absolutely gross) and pull the power head to extract bolts. While I was at it I replaced all the gaskets and thoroughly cleaned everything. Got it all back together and now get far more water than this baby has seen in a long time. So much so, that it’s leaking water out of the top of the drive shaft but under the power head (not into the bottom cowling). Just above the mid section towards the transom where the drive shaft spins. Right above the apron. I’m not sure what to do at this point. So I started to rebuild the water pump again hoping to avoid pulling the power head off once more. Any ideas?? I have been spinning my wheels trying to sort this thing out. Once I get the lower unit back on I’ll fire it up to see if that helped. If not I guess I’ll pull the power head and my hair out.

[@alanberner-h5j]

very good , clear speaking , easy too follow

[@BornAgainBoating]

Thank you

[@Phosgenius45967]

Awesome video! Thank you. Learned a lot!

[@Nolaman70]

Extremely helpful. Thank you. Going get a pressure tester tomorrow as I saw oil in the water today. Next drain, and see if it's milky, Pressure 10 - 12 psi and soapy water if it's dropping pressure. Go from there... Hopefully, it's not the inner one.

[@kaotix147]

Thanks for video. I recently purchase a 91 chris craft with a 3.0l omc cobera stern drive. I believe the engine is a 89 thought not 100% on that. I need to replace the screw dip stick gasket, vent gasket and drain plug gasket. It been super difficult trying to find the correct part as I see o-rings, flat gasket, and also what appears to be a hard plastic material gasket. Any advice in how to find the correct gasket?

[@G_Machine_Joe]

Thanks BaB 👍 Where do you normally go for your Yamaha parts like seals? Might be tearing my F115 Yammy lower end off this Spring...on my '03 KeyWest 1720.

[@BornAgainBoating]

You can get a discount here: shareasale.com/r.cfm?b=1991037&u=3159438&m=119617&urllink=&afftrack= Just look up your model and engine and what not, they have maintenance kits for those engines as well

[@PapaMav]

Great vid; thank you.

[@stanleyhasting6047]

What about the big round gasket?That holds that lower unit in place before you get to the gears?

[@transientboater]

Doing a confessional, beads are in hand for penance. I never used a crush washer on vent or bleed. Why, one may ask. It came down to doing a trip where I had to make schedule. To button up the list to leave, I had to change the lower units lube. Yep, lost the washers in one of those plastic catch cans with 16 quarts of old oil. I digress a moment on this- it was a wal mart catch can that never would drain in to its well without drilling out the drain. Yeah, the first washer went into the drink. I pondered that for a moment. 'do I use the remaining washer at the vent or for the drain on the lower unit'? I had teflon tape for gas pipe and used it. I don't remember if it was used on the vent or drain at the time, but kept using the method of gas pipe tape. That Merc 115 2 stroke was rock solid, gutless above 4k altitude but damn, it was all was good when I changed the oil in the lower unit at the end of season. Thanks for the content. There are many in to cars/trucks and then there are us into boats and the outboards.

[@gazzachampas8058]

Hi my Yamaha 115 2 stroke is leaking oil. Not from the prop shaft seals as I wiped dry. Has oil in the bottom when I push my finger in has a lot of oil over. Which seal could that be. Thanks heaps. O by the way. Best videos 😊

[@BornAgainBoating]

Thank you, but I'm not really sure what you are talking about or where you are talking about, it could be exhaust oil that you are talking about but I'm not sure, sorry

[@gazzachampas8058]

@ I think the gearbox oil I coming from the o ring deep inside the gearbox. Could this o ring leak gearbox oil. Thanks heaps.

[@gazzachampas8058]

@ just a follow up. I found the issues. Last person who put in the prop shaft seals cracked the bearing carrier and was leaking oil through the crack. New carrier ordered. Was the last one in Australia. Lucky.

[@jerryq1000]

More great information. Helps to know what's inside so if there is an. issue, it's not quite as intimidating.

[@wadenorton35]

Hey there, if my prop shaft is scratched where the seals go is it possible to spin the shaft on a lathe and use some fine grit sandpaper or emory to smooth it down some? how tight are the tolerences between the seals and shaft? Are you able to get oversized seals or would taking a couple of thousands off make any difference?

[@BornAgainBoating]

It's possible, tolerances are super tight though, try the o-ring trick first: kzbin.info/www/bejne/h3_ZoZqpbsRoqJY

[@motorv8N]

Great lesson - that’s about 4 more leak points than I thought there were!

[@BornAgainBoating]

:)

[@markgrand3346]

Is that a OMC stern drive? Hiw did you drop that part? I’m looking to replace water pump impeller.

[@BornAgainBoating]

No, it's an outboard lower, OMC stern drives are different because they have an upper and a lower, but the stern drive lower has basically the same types of seals

[@acme9538]

What is the estimated life under normal use these Yamaha seals last? I'm at 575 trouble free hours on a Yamaha F70 . . . best motor I've ever had. Great Video . . . new subscriber !

[@Nolaman70]

I have no real answer. I only wanted to say salt water will be sooner.

[@BornAgainBoating]

There isn't an answer lol some last years and years and hours and hours and others fail in a couple years :/ really it's usually the spring on the seal that rusts and fails :/

[@KevinGreen-z6m]

Can I do the pressure test without removing lower unit. Observe constant pressure for a period of time to confirm that there is no leak or will it be obvious there is a leak when I drain the unit?

[@BornAgainBoating]

Yes, but if there is a leak you'll have to remove it, no leak, change the fluid and send it, normally we don't pressure test them unless there is a leak and you can see water in the oil :/

[@boshmarine7696]

Well explained thank a lot

[@fixinanddoinstuff2134]

New subscriber. Any ideas or maybe chance for a video on why water would come out of lower unit mating surface to mid point while the water mufflers/garden hose is on. Thanks

[@BornAgainBoating]

If I'm thinking about what you are saying correctly, it's just where the exhaust dumps out and the water is just there so with it being out of the water on the trailer it will come out of there

[@krisramos7453]

Why don't motors have some sort of sheer pins to protect all the shafts and gears if you smack something? I know my old boat had an aluminum prop which from experience I can tell you it bends before any damage happens to the shaft. But the stronger stainless props I'm not sure.

[@BornAgainBoating]

Nope, not really any pins or anything that can be for protection or else it weakens and creates failure points in the engine. But the trim units have bypass valves that are supposed to allow the engine to pop up out of the water when you hit something, but it takes a good hit for that to happen. There are some Prop Hub designs that do something similar, but there are a lot of solid hubs as well for performance, and no, stainless is not going to give much lol with a solid hun and stainless prop, the lower unit is what is going to give. That's the back and forth discussion, it depends on how you use your boat and what you are looking for, both have their benefits.

[@thetruejuanalto]

if the lube gets refilled does it stop the aeration and warping of seals? or are they sealed units that require replacement of seals before servicing...? ty ty

[@slimmm723]

excellent. What about a cracked housing?

[@cmmaine100]

Will this cause the Gear Lube/Oil reservoir in the Bilge compartment to erupt itsCap off, and spray lube INTO the Bilge/Motor compartment?

[@BornAgainBoating]

There could be a couple of things going on that will pressurize the lube. It happens when the lube heats up so there is that, there could be a problem with the cap, but then more than likely there is a leak and water is getting into the gearcase and pushing the lube up and pressurizing the case when ran, you should check you gear lube and service the lower unit and pressure test it.

[@tylerdegrand3034]

I've noticed a lot of water leaking from my intake vents after boating. It's only water, no oil. To be sure, I changed my gear lube oil and found no water in there. Should I be concerned? I trailer my boat and never used to have a puddle of water in my garage after each outing, but now I do. Also, I don't lower the unit after each outing; it's trimmed up and only lowered when in the water or when working on it. Thanks for the Great video!

[@BornAgainBoating]

Most likely nothing, water will be coming out the intakes of the lower unit for a little while after using the engine, that is just water draining from the engine, the exhaust, the lower unit around the bearing carrier, and the rest of the cooling system. Especially if you trim it down after using it, all the water in the lower will drain out around the prop. Straight water isn't a problem that is coming out the water intakes of the lower after using it. Not sure how you didn't notice it before though, but from what you are describing doesn't sound like an issue

[@tylerdegrand3034]

@@BornAgainBoating Thanks for the detailed response!

[@dereckhunter3131]

Hey born again boating I have a alpha one GEN two lower unit that’s leaking oil out weep hole, I just recently purchased this boat and had to install the lower unit onto the boat and I filled it up and now it’s leaking out that hole. What should I do?

[@BornAgainBoating]

Well, you gotta follow the oil leak, figure out where it is coming, is it just residual from when you filled up the lower? Or is it used oil that is coming from somewhere else? For an oil leak you just have to trace the oil leak back to the source :) I'd try and clean it all up the best you can, then, you said you filled it, so all the oils should be full. Run it on the hose there at the hose and let it run for 5-10 minutes. Then shut it off and look around and inspect to see if the oil starts leaking out again. If it does, follow it back, and if it doesn't, it sounds like residual

[@p1mm3]

Bought a brand new motor on auction from a company for 2 weeks ago. Havent even been out on the lake yet but when its tilted theres a oil leakage from 2 small holes located in front of the shift shaft. :( I cant determine if its gearhouse oil or not because it feels more lubricant and thinner but at the same time it does not smell like motoroil.. Could it be gearhouse oil anyways? I filled oil from the level plug because there was already a bit of oil in it but not so much..

[@BornAgainBoating]

Most likely it is engine oil, but it could be gear lube, though if it's gear lube the lower unit has an issue, if it's an SEI that would make sense, but brand new, it's probably OEM and most likely oil

[@libingliang7967]

One question: Do I need to drain the lube before the pressure test?

[@PrefersAnonymity]

No

[@whoabigthymer]

Haven't seen Donny in awhile. Is he still a part of the team?

[@marklaw2845]

Great video!!

[@nwrx247]

With muffs on,engine running is the lower end unit supposed to get warm like hot .would that be normal

[@BornAgainBoating]

I would say warm is normal, but hot, depending on what hot means, no that would not be normal, might have a friction issue, but it will produce heat just really depends on what you say when you say hot

[@allanfaust1011]

I have a similar shift shaft. after changing my water pump, when i put the lower end back in, my tranny wont shift (F, N or R) I know the top is shifting (when i looked in the top end and went through all 3 gears). Could it be because its pushing it up and not engaging, or what?

[@BornAgainBoating]

You probably missed the shift shaft all together my friend! You should take the bolts out of the lower unit and lower it slowly, looking at the shift shaft and see if you got it up into the shift shaft on the engine :) most likely it missed and so you just need to put it up so they go together and you'll be fine ;)

[@allanfaust1011]

@@BornAgainBoatingThx… no, i didn’t miss it… decided to go it e more try theis afternoon…lowered it,put it in forward up front… switched the shaft to neutral then forward, lifted back in and it popped into place… the plastic unit in the upper unit holds th upper part of the shaft in place, so I don’t believe I missed it, but glad. It’s finally fixed

[@allanfaust1011]

I take that back… not flexed… tried it on the water and forward is now reverse and reverse is forward,,,

[@K_M_M_G]

I’d love to have that 2-stroke 90 Yamaha

[@glorialaltisimo]

An aligator at 60mph will cause a leak, a reef, a chain, and a rock. Also, if you don't change the oil, or if your shift cable is adjusted wrong, and your gears come out of the side of the lower unit, will cause water intrussion

[@gregfeldman6818]

Try to keep the gears inside the case, if possible.

[@mikewehner2858]

How do you get that bearing carrier out ? I don't see any screws etc to loosin it. 2007 150hp Yamaha

[@BornAgainBoating]

Hey! Rose here, supporting Aaron with comments. Thank you for your comment! I've saved it for a detailed response/illustration in a future upload. Be sure to tune in so you don't miss it!

[@Gregg0112]

Do the lower units have vents? I couldn’t see one on my f50 lower unit.

[@BornAgainBoating]

Idk what you mean by vent? Make a new comment so it goes to the top of the list ;)

[@lewisbenjamin5298]

I cannot find a 3/8 pressure tester anywhere.

[@lliamnapoleon5167]

Nice video.

[@gregfeldman6818]

Best I’ve seen

[@bennyramirez3942]

Got a lower unit that bad what is the same as a nissan lower unit

[@SebP-h7k]

What a great one! Thanks! 👍

[@bengilluyando9489]

Thank you so much for these videos

[@BornAgainBoating]

You are welcome!

[@davidd8435]

I am going to makes these videos for a boat maintenance library there are a lot of information in these videos. Are you working on your boat or a customer's boat?

[@gregfeldman6818]

Don’t Poach the Man’s Work

[@BornAgainBoating]

:) it's a buddy of mines boat

[@1celtickiwi]

this is a great vid. cheers mate

[@motodiver6720]

❤

[@iknowgood2403]

Nice

[@andreireal9158]

also a gearcase oil dripping from the water intake grate is a sign that driveshaft seal is failing

[@kenn1320]

Interesting. I have a 2019 merc and gear lube leaking from the coolant drain towards the bottom. This is typically the drive shaft seal?

[@robertjackson7590]

Spring side should go to the oil, that's the direction I installed them. Great video as always.

[@antho7475]

That's not correct,They are installed that way to allow pressure out when you run for a long time and the oil gets hot and expands, sort of like a breather in your cars differential or transmission. Also when a hot lower unit cools at the ramp or trolling after a long top rpm run back from Bimini , The oil contracts and water can be drawn into the lower unit through the prop seals . That is considered " normal"

[@robertjackson7590]

@@antho7475 I had seen people find low oil levels and next to no oil in Yamaha LU's. I did when I bought mine used. I understand what you're saying but I've had no problems and correct me if all the LU's from all the companies in the past worked fine with the inner seal lip facing the oil? As long as it has room to expand when it warms up it can't hydraulic the seals out. The hot oil doesn't expand more than 1/2 to 3/4inch from the top screw if that much. Shouldn't blow the seal from that. The inner seal spring faces the oil, the outer faces the water. That's what I did. I don't put a lot of hours on mine I admit. PS even with the pad at times. I do appreciate the explanation on their intent. kzbin.info/www/bejne/Y4HEaZKAoNBkrcU

[@antho7475]

@@robertjackson7590 Thank you . that makes sense also l think l will try that next time . Who knows maybe Yamaha planed it that way in order to sell more LU. 😀😀

[@robertjackson7590]

@@antho7475 Run a good syn gear oil like Amsoil and if you run 24-25 pitch or more bypass the Neutral safety and start it in gear. The LU will last years longer.