I know this will seem elementary to most of you, but I am trying. I changed out the oil in my lower unit today. I filled it up from the bottom, no problem. Oil started coming out of vent hole on top, so I capped it off. After unscrewing the pump from the bottom, the oil started coming out. Had a little trouble getting the drain plug in and lost a little bit of oil. Don’t think it was a lot but I wouldn’t know. So my question is how do I check the level of the oil. I have a 2002 Merc. 90 2 stroke. It has 3 holes; drain, vent, and one other one on the top. Sorry for such a simple question, and as always I appreciate your help. Have a good one.
The best way to a fisherman’s heart is through his fly.
When you take the vent screw out should be able to see oil or stick you finger in the hole and feel oil. Your gearcase holds 2.5 ozs.
before you put the upper screw in, i suggest letting the motor sit a few minutes, then give it another pump of gear oil.
sometimes air bubbles get trapped in the gear case.
Shouldn’t one let just a little, maybe 1/8oz or less out of 2.5oz run out and then put plug back in to give room for oil expansion when the oil gets warm?
Russ B.
God is great, Beer is good, People are crazy
If you are worried about it you can add some oil through the vent hole. It might be a little messy, just add straight from the “bottle” nipple by sort of shooting it in. As Chris V said there really is plenty of room in there.
I have the same engine. What are the 2 top screws for? One is the vent and the other the top fill? I changed my oil a couple months back and I hope I did it correctly. Also, would you use Locktite on the screw threads? I didn’t feel like i could get these tight enough and if they backed out it would not be a good thing.