Lower Unit Full Water - Replace necessary?

Pulled the boat out for the winter and found that the lower unit was full of saltwater.... barely a scent of oil. It is a 1999 Johnson 200hp OceanPro. I then flushed with fresh water a number of times, refilled with new oil, and ran engine to distribute around gearcase. I assume it was like this most of the summer (4 months since last changed LU oil) and used quite a bit that I am surprised it didn't seize. No idea how much corrosion could have occurred. Not a lot of metal shavings found on screws.

History: Previously had a issue with it having a hard time fulling engaging when being put into gear which was resolved by adjusting shift rod height, but after a while it started doing the same thing again. This lead me to believe my cables might need to be replaced, but now I'm thinking the teeth might have started to wear.

Do I need to junk this lower unit or can I find the leak, reseal, and continue running with new oil? Other than being stranded out of the water, what kind of damage can result if the LU freezes up on me while running?

Re: Lower Unit Full Water - Replace necessary?

An instant siezure is pretty rare unless something actually breaks. If a bearing goes, most likely, it will just slow down.

You may be lucky. Try it. Did you replace the fill/drain plug seals? That is the most likely place for water intrusion.

Re: Lower Unit Full Water - Replace necessary?

Two things you can do. Tear it down, give it a good inspection and reseal it. Or, fill it with oil and run it to see if it blows.

Re: Lower Unit Full Water - Replace necessary?

Myself, I would fill it up once with fresh new oil and check the condition of the oil after one use. If you see a lot of water has got in and milked up your oil, then it would be a good time to tear it down for an inspection/re-seal. Big horsepower = big bucks, if one of those gears should go.

Re: Lower Unit Full Water - Replace necessary?

If the lower unit goes on me while in use, is there any risk that something other than the lower unit will be damaged causeing me to be worse off? If not, it seems like I don't have much to lose by resealing and reusing. I did replace the plug seals when I drained/refilled last time. If I was to reuse, my plan was to do a pressure test to find the leak, then simply reseal and refill.

What exactly do you mean by "tear it down"? Full dissassembly? Partial dissassembly? I've done all the engine work on the outboard but I've read the lower unit is something to leave to the pros. Although I do have all winter to play with it in my garage. A was told by a local shop a rebuild would cost over a $1000 so I think I would buy a new SEI lower unit for $900 instead of rebuild.

Re: Lower Unit Full Water - Replace necessary?

A lower unit isn't horribly complicated. Hey, I've successfully worked on one with help from a factory manual, which proves that it doesn't take a genius. I'm thinking on your lower unit you can pull the bearing housing fairly easily, and with that out you should be able to look around inside (without having to do the difficult disassembly) to see if you see any severe ugliness. Take a look at the parts diagram at shop2.evinrude.com to see what you think. And of course finding an OMC factory service manual would be a huge help as well.

Re: Lower Unit Full Water - Replace necessary?

Thanks metric. If i pull the bearing housing, will I be able to see/inspect the cluth dog from that point or do I have to dig further potentially to the point of no return. I have the factory service manual and will read through that section. Just don't want to spend $100 on a seal kit plus replacement parts is failure is likely going to be inevitable resulting in dropping another grand on a new aftermarker unit, but it doesn't seem like anyone who has responded has even made the thought of cutting my losses and buying a new aftermarket unit...

Is there any risk to the driveshaft or other components of the motor if I run the lower unit until it blows?

Re: Lower Unit Full Water - Replace necessary?

It is possible to damage the powerhead if a gear or bearing suddenly seized, I agree with above though, they normally slowly wear down.

That being said, why risk it? A reseal is not that big a deal. No one has mentioned buying another gearcase because a reseal is a common practise and not that difficult after doing a couple. For your first, I would HIGHLY reccomend you have a factory OEM manual with you.

Re: Lower Unit Full Water - Replace necessary?

Thanks HighTrim. I will read through my factory manual. What type of symptoms indicate it wearing down? I have noticed that sometimes when i put into gear, it will fully engage and then I will hear it clanking like it is slipping and then catching again. This is only when putting around (usually when approaching a dock or mooring) and not once I give it more throttle. Also, when cold and in gear, the idle will sometimes drop below 700 rpm as if it was going to stall.... when this happens it almost always will make the clanking like it was slipping out of gear. So long story short, it happens at very low rpms and never above "no wake" speed. Make sure shift rod height was at spec and adjusted shift cables accordingly, however did notice about 1" to 1.5" of play in the cable (i.e. disconnect cable and pull plastic end shaft all the way out and then all the way in. Not sure if the cable is supposed to have that much play.

Re: Lower Unit Full Water - Replace necessary?

If i pull the bearing housing, will I be able to see/inspect the cluth dog from that point

Click to expand...

You'd need to get the reverse gear out to see the clutch dog, and I can't remember if you'll be able to take that out or not at this level of disassembly. And what I was thinking of was just being able to do a general inspection to see if there's corrosion etc. on anything, plus with the bearing carrier out you'll be able to see what the bearings look like.

The tricky part of complete disassembly/reassembly is removing/installing the pinion nut. You need a special wrench to hold the splines on the driveshaft (I made one on a waterjet), and even with that getting to the pinion nut induced a lot of bad language. Sometimes you can find a shop that will help you with just a little part of a job like that - one of the gearcases I had was the older style which needed special snap-ring pliers ($80 to $100) but I had a mechanic at my local marine dealer pull and install the snap rings for $10.

however did notice about 1" to 1.5" of play in the cable (i.e. disconnect cable and pull plastic end shaft all the way out and then all the way in. Not sure if the cable is supposed to have that much play.

Click to expand...

A little bit of play is normal, but not that much.

Re: Lower Unit Full Water - Replace necessary?

Clutch dog failure is usually noticed at high RPMS. Sounds to me like an adjustment issue, or worn cables. Also be sure to snap the shifter into gear in a sure, quick movement, gently easing it into gear only wears the gears and dog more.

Re: Lower Unit Full Water - Replace necessary?

$1000 for a re-seal job? Holy smoke! You can do it for a heck of a lot less than that, yourself. Seal kit alone for your motor should easily be less than $100. Any other parts that are worn, should be obtainable, with some good research and careful shopping.

Re: Lower Unit Full Water - Replace necessary?

Good to know HighTrim. I definately snap the shifter into gear in a quick motion. Trust me, I went through a childhood of hearing that dreadfull grinding whenever my father would put the lakeboat into gear. No matter how much I tell him, still does it to this day! haha

Zephyr - $1000 for full teardown and rebuild.... $100 for seal kit.

Looks like my plan is to pressure test, find leak, reseal, and continue to use same lower unit next summer. If I get bored this winter I'll opt to do a more thorough inspection and pull out gear housing and take a look around for corrosion and at bearings.

Thanks for the help everyone. If there is anything else to add, please do as I'll keep checking this post.

Re: Lower Unit Full Water - Replace necessary?

$1000 for full teardown and rebuild.... $100 for seal kit.

Click to expand...

You can usually find decent lower units on ebay for a couple hundred bucks, and as you know $900 for a new SEI.

If there is anything else to add, please do as I'll keep checking this post.

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Don't forget that shift cable. I just checked the shift and throttle cables on my boat that has the engine off right now and I'm only seeing about 1/8" of play on the cable ends.

Re: Lower Unit Full Water - Replace necessary?

Wow, only 1/8"... that's a huge difference. I'll be replacing the cables too after hearing that! Thanks for checking yours as a comparison. much appreciated.

Re: Lower Unit Full Water - Replace necessary?

Taking pictures of the parts as they are taking out of the LU will be helpful for referance when you go to put it back together, if you teardown the LU for total rebuild or checking the condition of the gears and clutch dog. A picture is worth a thousand words. JMO
Oldman570

Re: Lower Unit Full Water - Replace necessary?

My manual lists 21 special tools, jigs, fixtures, gauges for a gear case job plus selecting shims, making precision measurements and other really grown up stuff.
Way beyond my pay grade.
Trouble is the so called pros in Antigua are far worse than me and the only real dealer is a Yamaha man.
I guess its over the side for my 200.

Re: Lower Unit Full Water - Replace necessary?

If you think that the damage is more than you want to handle you can check on Ebay for a used or rebuilt LU as there are some listed for sale. Would still be cheaper than a diffrent motor. JMO
Oldman570

Re: Lower Unit Full Water - Replace necessary?

UPDATE: Finally had time to work on the lower unit. I pressure tested and found the leak to be the prop shaft seals. I was able to remove the bearing carrier and made a visual inspection. From what I could see, there was no rust visible within the lower unit other than a little yellow/orange discoloring on the bearing within the carrier closest to the prop end. Both bearing within the carrier spun freely. I plan to replace discolored bearing, reseal, reassemble, fill with oil and use this spring as it.

Before I do so, should I remove the thrust washer, thrust bearing, and reverse gear to inspect further or am I at the point where I shouldn't go any further without being an expert? It looks to me if I can pull out the reverse gear, then I can get a better look at the teeth, just nervous to continue digging...

Re: Lower Unit Full Water - Replace necessary?

Resealing a lower unit is as easy as cooking a plate of chips.
it realy is not a hard job to completely strip down a gearbox.
i could take that box apart quicker than most people take to wash down their boats.

when you do decide to do it, take plenty of pics if its your first gearbox off job.
before you take the box off i would take off the prop and undo the main bearing/carrier,its easier if its on the
engine with it half tilt to get it off.
If the front seal as gone youl be able to see that straight away, if its a top seal again that is easy to replace.

But before you strip it down,do a simple test on it.
put a nice drop of new oil in it and run it in a tub for half hour in neutral, then check to see if any water has got in the leg.
if not then take the prop off and put it in gear and run again for half an hour and re-check etc.
no point checking it when cold as the oil will be thicker and not seep out,with a warm engine and warm oil you
see more !!
check around the shaft for any fishing twine !!! that can often destroy a front seal.

once you start looking youl see its an easy job, if youve worked on the top of the outboard then you can
certainly do the bottom.
the leg is easier than the powerhead to work on by a long way.

with the right tools to strip the box down wont take you anymore more than a couple of hours.
i took one apart recently took 45 minutes from being on the boat to in bits in a box on the bench and im not a
outboard mechanic by a long way.

good luck and lets us all know the outcome once your happy with it again.
Like said above, get a manual, they are worth their weight in gold and give you something to
read in the cold evenings.
once you attack it it will all make sense and youl enjoy getting it back to 100% again.




phill