lower unit oil change messy

[BIGKASH]

Why is it that you have to fill oil from the bottom of the unit, I had to inject to tubes 10oz each into it until it cam out the top. I then screwed the fill/drain in then the vent...did i do this right, I have manual that said do it that way.

 

[BIGKASH]

Re: lower unit oil change messy

200hp mercury 1983...thanks

 

[12Footer]

Re: lower unit oil change messy

Yes, you sure did it right, and it's allways a mess. Make sure you use new gaskets on the vent/ fill screws.<br />And have that bottle of GoJo and a pakage of wipe-alls and oil-sorb handy The reason is becaudse if you were to try to filll t from the top, trapped air would build up inside the case as you filled it, it would soon build up enough back pressure to prevent any lube from going into the case, and have the nasty side-effect of spraying out the top hole, any that acually made it in there, asd soon as the nozzle was removed.<br />At least, that's what happened when i tried it many moons ago..And I had to clean up a real messy driveway (my dad's)..He was unhappy with me.

 

[magicbandit]

Re: lower unit oil change messy

Maybe it is to get the air out of the unit

 

[boatingfool]

Re: lower unit oil change messy

Nearest I can figure is if you fill it from the top you will get air pressure built up inside the lower unit and possibly damage some seals.<br /><br />I say this because I tried filling from the top and it got hard to pump in.<br />I thought maybe it was full but when I loosened the filler hose a lot of air escaped and it was no where near full.<br /><br />If you fill from the bottom and the top fill plug is out then the air escapes out the top and no pressure builds up.

 

[12Footer]

Re: lower unit oil change messy

I know what u mean..It flies in the face of logic, don't it?<br />

 

[Jack Shellac]

Re: lower unit oil change messy

You can get a pump that screws onto a quart bottle of lower unit oil. It screws into the drain hole. You put it in and then take the vent screw out. Fill it, put the vent screw back in, remove the pump fitting and put the drain screw back in. The vent screw being in keeps the oil from running out quickly and you don't get such a mess. Some, but not nearly as much. It works well for me and you may like it. Much easier than holding a tube in place while you squeeze, etc.

 

[Dhadley]

Re: lower unit oil change messy

When you fill it from the bottom and fluid starts to come out the top, install the top plug while the fill tube is still in the bottom hole. Then you wont lose as much when you quickly start the bottom plug. <br /><br />Precision Manufacturing makes a trick little deal thats a one way, spring loaded piece that screws in the top (vent). It automaticaly closes when you stop pumping fluid in. Makes putting in the bottom plug a snap with a minimum of fluid loss. Then unscrew it and replace the top plug.<br /><br />Good luck!

 

[ob]

Re: lower unit oil change messy

I use a wedge type screw holder to make the job of installing the vent screw a bit easier after filling from bottom hole.It prevents having to fumble the screw by hand tring to start it.It is necessary to fill from bottom hole to prevent air pockets from forming if filling from top and insures a true fill of the gearcase.If you happen to have two of these wedge type screw holders you can also insert the bottom screw with the other one when you are finished filling.Insert both screws into the holders before filling begins.

 

[BIGKASH]

Re: lower unit oil change messy

thanks guys, i might try that pump thing, I loss so much oil putting the plug back in. I may have to add more oil with the pump...

 

[Reel Appeal]

Re: lower unit oil change messy

BIGKASH,<br /> There is a better and less messy way to change lower unit oil.Not sure about Mercury lube,but OMC/Bombardier makes quart size containers with a pump/hose and threaded fitting w/o-ring on the end.The fitting screws into the drain hole.After draining,screw the fitting in bottom hole and fill until fluid has reached upper vent hole threads.Replace the upper vent screw/plug and tighten.Unscrew fitting from drain hole and replace lower(drain)plug.Very little fluid is lost(teaspoon at most).One piece of paper towel should take care of the mess....What mess? <br />(edit)Ahh sorry ,just do what Jack says....

 

[boatingfool]

Re: lower unit oil change messy

Reel Appeal,<br /><br />You can get those at any boat store.<br />Atleast that is where I got mine.<br /><br />Putting in lower unit oil without the hand pump is like trying to cut a steak with a plastic spoon.

 

[miloman]

Re: lower unit oil change messy

never a clean job I use a pump to fill and yes always fill from the bottom as to prevent air pockets which as everyone says can cause problems none the least not enough oil in the gear case

 

[John from Madison CT]

Re: lower unit oil change messy

You've got to get that pump and the quart bottles.<br /><br />Those 10oz. tubes are for small engines. The pump makes for a clean job. All the larger boat stores have them. Be SURE to get the small adapter for Yamaha engines. I believe it's a metric converter.<br /><br />John from Madison, CT

 

[Lark40]

Re: lower unit oil change messy

One other suggestion. Wear latex surgical gloves. <br /><br />I work alot on old cars and boats. First thing I do when entering the garage is slip those on, especially when greasing stuff. No cleanup needed.

 

[gss036]

Re: lower unit oil change messy

I just did two engines yesterday, 200 Merc and a 15 hp honda. I didn't have the adapter for the Honda, have to get one, I had kinda of a mess trying to squeeze from a half full quart bottle. I didn't have a full one to work from.<br />Anyway, I have always been of the understanding that filling from the bottom not only removes the air bubbles, but allows a small amount of oil to escape so the you have room for expansion when it gets warms.