Changing Lower Unit Gear Oil

[Hook1]

So I've done this several times since owning my boat. Problem is I always make a big mess. The only good way I've found to do it is to use a 1/4" rubber hose and put it over the cap of the new gear oil bottle and try to "squeeze" the oil in. I still get lots of drip and runs that have to be cleaned up. So my question is; how do some of you other guys put new gear oil in your outboards? I'm trying to find a better way to cut down on mess and waste. The holes on my motor where you remove the plugs is in a pretty deep recessed area and there just doesn't seem to be a good way to pour the new oil in. Thanks for any advice and ideas.

 

[Gone fishin]

I have a device that screws into the plug hole with a hose attached to a cap that goes on bottle and you pump it in. Works real good.

 

[Gone fishin]

Google lower unit gear lube pump

 

[chillerman69]

Wally world has them. I think Attwood makes them but not sure.

 

[catch 1]

Use filling tool mentioned. Fill from bottom plug with with the upper plug removed. Fill till oil reaches bottom of upper vent hole. Don't over fill because it will heat up and expand blowing seals. Put the upper plug in. This will help keep the oil from running out when you remove the fill tube. I would also replace the gaskets on the two plugs.

 

[Hook1]

That pump looks exactly like what I need thanks!

 

[BRamsey]

Pump works great and pretty cheap.

 

[gonefishing31]

Pump is way to go walmart has one fairly cheap

 

[captain kirk]

You may have two vent plugs on your unit. If so, remove both and fill until oil comes out the first, then replace that plug. Continue to fill until oil flows from the upper one, then replace that plug.

 

[Hook1]

Yes it does. It has an upper vent, one slightly lower marked "oil level" and one drain on the bottom on the foot. Are you guys suggesting to fill the foot from the drain plug? I've definitely never tried that.

 

[porthos33]

Hook1 - Are you guys suggesting to fill the foot from the drain plug? I've definitely never tried that.

</p>

Yes, it is the only way to do it so that you won't get air bubbles. Also once it starts running out the top hole it is full. Then plug the top hole first and the oil won't come out freely when you take the hose off. I think the little kit from walmart is only like 7 bucks.</p>

 

[chillerman69]

Filling from the bottom, putting top plug in before you unscrew pump hose and getting new seals or O-rings are all exactly right as several others have suggested. I just want to add a few tweaks: once the fluid has been pumped in, give it a few minutes for the air bubbles to work their way out before putting top plug in. Get several drain/vent seals or O-rings because shipping or drive cost more than the extras and you never know when you may have to use them. Make sure you have the correct size screwdriver for the job, it'll make it easier to do the job and won't mess the slot on the drain and vent. While the seals are pretty cheap, the drain and vent screws are kinda high for something so small.

 

[Hook1]

Thanks chillerman. I usually let it sit for several minutes before installing the plugs. I just usually pump the oil in the top. I do wait for a warmer day so the oil goes in and out easier. I'll try the better method next time.

 

[Gator]

Filling from the bottom is the right way to do it. The pump makes it easier but I always have a mess anyway.
I never found a pump with threads for a Mercury. Mine doesn't have threads therefore a mess.

 

[chillerman69]

Gator - 3/6/2017 8:12 PM

Filling from the bottom is the right way to do it. The pump makes it easier but I always have a mess anyway.
I never found a pump with threads for a Mercury. Mine doesn't have threads therefore a mess.

I don't have Black on Back but thought the Attwood fit everything.

 

[TR20bh]

Hook, just make sure you replace the washers on your plugs. They are crush washers & if you try to re-use them, they will leak & you'll end up with water in your lower unit.

 

[Hook1]

Where's a good place to get these washers anyway?