Gear Oil Change

V

vanisland

Member
Decided to change the gear oil in my 94 merc 115 today and this is what came out. Im guessing water has gotten in which wouldn't surprise me as the drain plug wasn't even tight when I went to remove it. And on the vent screws only one had a washer and it was very deteriorated. The drain/fill plug screw had some metal shavings on it as well. No clue when the last time the oil was changed as I just bought the boat a year ago. I have a vacuum tester/bleeder but don't know if that will tell me anything about the seals in the lower unit. Im guessing I probably shouldn't just refill the oil and hope the no washers/loose drain plug was the problem. What would be my next step here.. Thanks IMG_0989.jpg
 
That's not bad. The legs heat up and cool which creates moisture and you get a bit of a milkshake. Load it back up and away you go.
 
Using a proper marine gear oil will keep the water contained
in the lube. you don't want separation.
you could vacuum test the leg and replace the seals
or just refill and check it more frequently.
 
I'd fill with marine grade oil and run it for a day then change it again. Then I'd watch it closely for awhile then start changing it twice a year there after.
 
You should be ok with fresh gear oil. I would check it after a few trips to see if it stays water free. Spinning the prop by hand as fast as you can in neutral and listening for bearing growl will confirm if there is damage you need to address sooner than later.
 
Prop shaft seal to my eye - Changing oil and checking the color often and regular will tell you how bad...maybe pull prop and check for line /debris around prop shaft where it goes into gearcase
Testing static wont tell you much
 
Appreciate the help guys. So I hooked up my vacuum tester to the threaded pump fitting that comes with the gear oil pump. I put negative pressure into the gear case and pressurized to 10psi. After 5 min it had gone down to 9 psi. Hard to say if it was the fittings that leaked a bit, cause they do do that. I also poured a bunch of the old gear oil into a clear cup and let it sit for an hour and it didn't separate. Does that seem ok.. Ive got a litre of Quicksilver gear lube that im going to put in which is what the manual recommends.
 
You have too much moisture in your gear case... your pressure test confirmed it..save yourself a huge bill later... and change all the seals
 
The other thing to check would be the shift shaft seal, which could also allow water penetration

I had my gear case tested with no pressure loss, and still get some moisture.
 
I have one of those testers-a 1 PSI loss is nothing-the guys above gave you good advice-new plug seals, new oil, check every trip for awhile and my guess is you'll be fine-wouldn't hurt to pull the prop, re-grease the spline and check for line while your at it. If line was present I might get suspicious about the prop seal-might buy one and have it on hand but I would still wait for a couple of runs.
 
He could get away without doing any repairs and change the oil more often to keep water to a minimum. However he should be looking at replacing the seals...the water didn't just get there by osmosis. if you do nothing it won't magically stop.
 
Hopefully it was just the gaskets on the screws but as long as you are aware of it and keep an eye on it just fill her up. Yes,the right thing to do would be to fully reseal the lower but you could be into a 500.00+ repair bill pretty quick.good chance the driveshaft and propshaft will be grooved where the seals ride as well.
 
That is such a minor amount, I agree with others that it could be condensation from normal warming and cooling. Same as the differential in your pickup.
 
I've had 2 - 9.9 high thrust Yami that had creamy gear oil after a season and a pressure test or vacuum test failed to produce any leaks. I went 3 seasons on the one I have now with this issue. I finally decided to replace all the seals and the oil has been water free since.
 
There is one major difference between vehicle differentials (and most other gear assy ) - In a marine lower unit on an outboard or sterndrive the casing is SEALED - there is no vent like a differential - so there should be no condensation especially since a leg is run in water so it never really heats up then cools off compared to an axle.
Creamy oil in a leg is due to something leaking.
 
Fish Assassin said:
To be on the safe side just buy a new motor :) Tell the wife it's was necessary LOL
Click to expand...
Lol. That's my line with the wife about every 3 years....looks like.... Honey, I'm all alone on the nasty big ocean. Waive the safety flag, and huck in you are fishing 30 miles off shore and how she won't want you floating around for 18 months on a dead motor like that poor Mexican dude! Works most times.
 
Lol some wives would just say they had hoped it would have broken down 30 miles offshore already. Forget the new motor just keep your life insurance topped up!
 
You must log in or register to reply here.

Similar threads

smokedvw
Struck gold! WTH is with the price of drain plug's and lower leg washers
Replies
13
Views
992
Alex_c
Alex_c
M
Yamaha 9.9 gear case stuck
Replies
11
Views
962
noluck
noluck
Slabbedout
4 stroke oil change
Replies
0
Views
191
Slabbedout
Slabbedout
DieselBeast
2007 (SOLD) 18ft Hewescraft SeaRunner $38,000 obo
Replies
1
Views
1K
DieselBeast
DieselBeast
Ugly Betty
Honda kicker with oil in carb!
Replies
7
Views
513
Prfisher
P
Back
Top