Lower Unit Fluid Change

fullsize_chevy

Seaman Apprentice
Joined
Jan 16, 2005
Messages
31
Today, I changed the fluid on my 2004 mercury 115hp carbureted 2stroke lower unit (for the first time). The fluid that drained out appeared nearly black with maybe a slight tint of blue in the light. I used Quicksilver High Performance gear lubricant for lower units, and it's boldly blue. Is that the same stuff that poured out, but it was really dirty causing the black color?
 

Rabbitdawghunter

Petty Officer 2nd Class
Joined
Jun 20, 2003
Messages
147
Re: Lower Unit Fluid Change

If its an 04 and you are just now changing for the first time I would say that's normal. The problems usually come with water infiltration into the gearcase via the seals. If the fluid was kind of milky that would indicate water and a vacuum and pressure check would be needed to find out where the water got in from.
 

gss036

Commander
Joined
Jan 18, 2003
Messages
2,914
Re: Lower Unit Fluid Change

That would be normal. You should have a little of metal dust stuck to the magnetic screw, which would also be normal. You should also put a new gasket in front of the drain screw.
 

fullsize_chevy

Seaman Apprentice
Joined
Jan 16, 2005
Messages
31
Re: Lower Unit Fluid Change

The manual did not mention replacing the drain screw gasket, so I just put it back. Should I have replaced it? I suppose I can always run it a couple hours in the spring and then change the fluid again replacing the gasket that time. Either way, it was cold outside, so the fluid was very viscous. It drained for over an hour. I may repeat after a little use in the spring.
 

fullsize_chevy

Seaman Apprentice
Joined
Jan 16, 2005
Messages
31
Re: Lower Unit Fluid Change

"If its an 04 and you are just now changing for the first time I would say that's normal"....<br /><br />The boat/motor were purchased in Dec. 04 brand new. It wasn't put in the water until April 05.
 

LubeDude

Admiral
Joined
Oct 8, 2003
Messages
6,945
Re: Lower Unit Fluid Change

Best to use new washers, but I dont always. Being cold out, you may not have got all of it out. I drain mine overnight even in the summer months. I use Amsoil, I like it not only for the performance, but because its more clear and you can see problems easier
 

aquaholictwo

Cadet
Joined
Dec 22, 2005
Messages
25
Re: Lower Unit Fluid Change

could this b the problem it was run over the course of the summer, thanks ,john.
 

gss036

Commander
Joined
Jan 18, 2003
Messages
2,914
Re: Lower Unit Fluid Change

Yes, metal to metal with the coarse threads do not seal all that well. It you got "lots" of water may be time for a pressure test. Better safe than sorry. You can try a new washer and see if it continues to leak. Just keep an eye on it.
 

andy6374

Lieutenant Commander
Joined
Aug 4, 2005
Messages
1,617
Re: Lower Unit Fluid Change

john11-<br />unless you noticed actual water coming out before the milky stuff I wouldn't get overly concerned just yet. Like gss036 said, without the washers you don't get a good seal. A tiniest bit of water, once churned up with the oil at 2000RPM will make it milky. <br /><br />Refill, replace the washers, take it for a good run, let it sit overnight (as the gear lube will appear milky even with no water in it after taking a ride) and take a look the next morning. If it is milky, then one or more of the lower unit seals are bad. But we will get to that if necessary.<br /><br />Good luck-<br />Andy
 

aquaholictwo

Cadet
Joined
Dec 22, 2005
Messages
25
Re: Lower Unit Fluid Change

I SAW ALOT OF H2O, BUT I WILL FILL WITH NEW OIL AND WASHERS,AND IN THE SPRING DO A RUN AND CHECK IT, THANKS FOR THE ADVICE ILL LET U NO WHAT HAPPENS JOHN11 MERRY CHRISTMAS
 

J.T.

Cadet
Joined
Jan 20, 2006
Messages
10
Re: Lower Unit Fluid Change

Make sure there was not one there to begin with. They have a way of sticking in the drain hole and you might need to help it a little.
 

timmathis

Lieutenant
Joined
Apr 24, 2005
Messages
1,295
Re: Lower Unit Fluid Change

Like they say, Change it replace washers run and recheck.
 

Texasmark

Supreme Mariner
Joined
Dec 20, 2005
Messages
14,642
Re: Lower Unit Fluid Change

Washers now are pale blue and should be easily visable if stuck in the lower unit housing.<br /><br />Agree, you can't run the lower unit without one as the threads aren't designed to seal on their own.<br />---------------<br />When you stick your outboard into water, the water is almost always cooler than the outside environment. So, as your lower unit cools down to this new environment, it creates an internal vacuum. The vacuum sucks water in via the screw threads if you don't seal it out.<br /><br />New, vs old, in a pinch, if the old one is not deformed, or torn I use them. But preference is to have some handy and always use a new one.<br />------------------------<br /><br />Agree with the bluish tent to near black Merc oil...Be tickled it was that color and not milky yellow. Grin<br /><br />FYI<br /><br />Got some Synthetic Pennzoil lower unit fluid the other day and it is gold in color (noticed it met GL-5 requirements and was not hypoid type (whatever that means) which is what they all used to be; very clear. Exceeds all mfgr's warranty requirements for mechanical shift engines. Got it at Wally world since my nearest merc dealer is 50 miles away, and it's made by Pennzoil, and if you can't trust them you can't trust yourself.....er ah..... Grin.<br /><br />Noticed Detroit has started putting syn oil in differentials of lotta new vehicles today. Great since it never gets any attention, and hard to drain, should provide superior service....course, when's the last time you lost a rearend in your vehicle?<br /><br />Mark
 

Laotzu

Petty Officer 2nd Class
Joined
Aug 1, 2004
Messages
150
Re: Lower Unit Fluid Change

How about the vent screws, they have washers too?<br /><br />Jerry
 

andy6374

Lieutenant Commander
Joined
Aug 4, 2005
Messages
1,617
Re: Lower Unit Fluid Change

Use washers in both the vent and fill/drain screws.
 

aquaholictwo

Cadet
Joined
Dec 22, 2005
Messages
25
Re: Lower Unit Fluid Change

ok thanks for the help.NOW I FOUND THE PROBLEM ,it is a hole in the lower unit the size of the tip of a pencil,it is in the back ;rt below the h2o line.can i fixed it with marine epoxy?
 

Texasmark

Supreme Mariner
Joined
Dec 20, 2005
Messages
14,642
Re: Lower Unit Fluid Change

Elaborate some more on this hole you found and help us to help you with the cause for it; if it's not supposed to be there.<br /><br />Mark
 

aquaholictwo

Cadet
Joined
Dec 22, 2005
Messages
25
Re: Lower Unit Fluid Change

the hole is on the leading edge, closer to the transom ,on the lower unit about 16 inches above the gear housing,but below the water line .The cause does not matter ,what i want to no ,is can it be repaired with marine -tex to prevent water from getting in the lower unit oil.
 
Top