I have a 1999 115 hp mercury outboard it looks like there are 2 vent plugs can someone answer this for me tks?

Question

I have a 1999 115 hp mercury outboard it looks like there are 2 vent plugs can someone answer this for me tks?

Answer 1

You have 2 plugs in the gear case. One is for the oil fill, the lower one, and the one above it is to tell you when the gear case is full of oil. Remove the lower plug and put the nozzel of the gear lube into the hole andhold it in the hole nice and tight,then remove the top plug and squeeze the tube of gear oil, when the oil starts to run out of the top hole,put the plug back into the top hole, then very quickly pull the tube of gear case oil out of the bottom hole and put the plug back in.

Answer 2

Kenbgray is right-on!

Answer 3

I agree with Ken.., they are on the lower unit,and this is part of normal maintenance, have you never filled the lower unit with oil?  Or are you talking about another area of the engine?  You can also push any water that might have entered the case if you carefully add oil at the lower plug while watching the oil/water mix come out the top-not absolutely necessary, but something to do.

Answer 4

Well if you have what I think you have one of those plugs could be for flushing out the motor.

Look close at the lower-unit the bottom plug is for draining the oil out, the upper plug just below the cavitation plate is for venting the oil and oil level and the other one above the cavitation plate is for flushing the motor after running in salt water.

There is a mercury adapter for the flush some times marked wash, if that's what we're talking about you can also run up the motor by using the Mercury adapter then no need for the ear muff type flush kit.

Hope this helps.