lower unit has water in it

[flounderman]

I started out today to run my f9.9mlhs yamaha on the muffs. Well, the lower unit lube was pure at the beginning of the session and 10 minutes later when done I decided to check the fluid,- - - the gear case had water in it . How did it get in there?

 

[WillyBWright]

Re: lower unit has water in it

It was either in there collected in a low spot, or it leaked in thru the seals under the watter pump.

 

[jerkin]

Re: lower unit has water in it

Could be the seals on the drain and fill screws also, I make a habit of replacing those often. They are usually under a buck a piece so I buy 8 at a time and that's enough to do both my motors twice.

 

[flounderman]

Re: lower unit has water in it

thanks guys, but i may have found my problem. did a teardown and the sealing surface on the drive shaft under the water pump has wear grooves in it, too deep to polish out so a new shaft may be needed.

 

[JUSTINTIME]

Re: lower unit has water in it

only 5 seals on lower unit

drive shaft
prop shaft
shift shaft
bearing carrier
drain/fill seals

 

[Paull911]

NEW THREAD: 2002 Yamaha 90 water in lower unit

NEW THREAD: 2002 Yamaha 90 water in lower unit

Bought a cherry used 2002 deck boat w/ 90 HP Yamaha in NC. Drove the boat before buying it (quite hard) on 11/19/06 and it worked slick, did lots of shifting, etc. and all was AOK.

Hauled boat back to MN and set about winterizing it. NC owner may never have done this and the boat was kept in water most to all year long.

I removed the screws from lower unit to drain it, so as to replace gear grease, and the fluid that came out seemed to be 100% water! Seriously, I could sense no lubricant in it at all. I was almost tempted to drink it to be sure, but didn't. I have drained many lower units in my day and I know what EP90 (even bad with some water in it) looks like and, believe me, this was no gear lube.

QUESTIONS:

1. Where did gear lube go?
2. Why did it work so well for me on the test drive?
3. Since it worked well last time out, if I replace seals and put in new gear lube, could I possibly be home free?

 

[even125]

Re: lower unit has water in it

Paul, many know much more than me bt will to have a go at your questions.

1. as the LU heats up from use the oil expands and is pushed past which-ever seal is not doing it's job. Then as the LU cools (at fishing spot) a partial vacume is formed (because of less oil now in case) and water is sucked back past the seal to equalise, then on the trip to the next spot it all happens again until nothing but water is inside the LU. Yours sounds like a catastrophic sealing failure to still be running.

2. They are very tough but not immune to abuse, i would assume the hard facing has been worn from the gears and a full rebuild will be in order although I may be wrong. Not to mention the bearings.

3. depends on 2 hope you are lucky here, I have looked into a replacement leg for my engine (same I think) and it seems at least to me that a full rebuild from running with water may not be much cheaper than an entire new leg complete and ready to bolt up.

The very best of luck with it.

cheers even125

 

[Capt Ken]

Re: lower unit has water in it

Always remember, oil has to go up to escape. If you find no oil in a unit and there isn't a big puddle of oil on the ground, its usually a seal under the water pump or shift shaft. If its the prop shaft seal, it will mix water with the oil, but most of the oil will still be there.