Merc 2004 9.9 - changing lower unit oil

[lakelover]

I changed the LU oil on my 9.9 today. The oil that drained out was very clean, no water or particles. I let it drain for about 15 minutes.

I'm wondering why, when I refilled it, it only took about 4+ oz. when the owner's manual lists the LU capacity as 6.8 oz? Normal? Air pockets?

About 6 oz. came out.

 

[carholme]

Re: Merc 2004 9.9 - changing lower unit oil

Sorry for the silly question but did you have the vent screw removed while you were doing it?

Gerry

 

[lakelover]

Re: Merc 2004 9.9 - changing lower unit oil

Yup, filled from bottom til overflow, put top screw in, then bottom screw after removing pump fitting.

 

[carholme]

Re: Merc 2004 9.9 - changing lower unit oil

Presuming that the engine was in the vertical position and you had oil coming out the Vent hole, you should have put in roughly the same amount that you drained. If it was mine, I'd drain it again, check the amount drained and re-fill very slowly.

Alternatively, give it a quick spin on the muffs and re-check to see if you can add more.

Gerry

 

[lakelover]

Re: Merc 2004 9.9 - changing lower unit oil

It's been sitting for a while now, I'll tip it up & back down a couple times & check it again. I wonder if there's a little air lock in there or something.

 

[lakelover]

Re: Merc 2004 9.9 - changing lower unit oil

Definitely full, less than half a stroke on the pump and out it comes from the top hole again. Must have been some residual oil in there is all I can figure.

 

[Jerry_NJ]

Re: Merc 2004 9.9 - changing lower unit oil

I just changed the LU oil (lubmatic) on my 1990 (purchased recently) Yamaha 9.9 HP. First I find the drain holes have a different thread than my Evinrude and Johnson engines - of course, metric. I purchased a new pump with an adapter listed just for Yamaha (is it the only imported engine to use metric? not a question, just strange to my mind) and all went well until I looked at the amount of oil it took to fill, bottom up. About 4 oz.

Reading this thread I'd say I have nothing to worry about. I don't have the owner manual.