Question about Boating

2 Answers

Which plugs do I remove to change my lower unit oil?

Posted by on


2 Answers

  • Level 1:

    An expert who has achieved level 1.

    Problem Solver:

    An expert who has answered 5 questions.

  • Contributor
  • 2 Answers

Both , the top is the vent.
Fill from the bottom up until the lube starts to come out the vent hole

Posted on Oct 27, 2011

  • Level 3:

    An expert who has achieved level 3 by getting 1000 points


    An expert that got 10 achievements.


    An expert that got 5 achievements.

    Vice President:

    An expert whose answer got voted for 100 times.

  • Master
  • 394 Answers

Both. The bottom one is the drain, the top one is the fill. The top one
needs to be removed to provide venting in order for the bottom one to drain.
Good fishing !!!!

Posted on Apr 27, 2010


1 Suggested Answer

  • 2 Answers

SOURCE: I have freestanding Series 8 dishwasher. Lately during the filling cycle water hammer is occurring. How can this be resolved

a 6ya expert can help you resolve that issue over the phone in a minute or two.
best thing about this new service is that you are never placed on hold and get to talk to real repairmen in the US.
the service is completely free and covers almost anything you can think of (from cars to computers, handyman, and even drones).
click here to download the app (for users in the US for now) and get all the help you need.

Posted on Jan 02, 2017

Add Your Answer

Uploading: 0%


Complete. Click "Add" to insert your video. Add



Related Questions:

1 Answer

What kind of gear case oil for 1972 4hp evinrude

EP 80-90 will do.Buy a small squeeze tub of gear case oil at most walmarts, etc. After draining, remove both upper and lower plugs, best if using a squeeze tube because you want to fill from the bottom up. Put the tube tightly in the bottom port and squeeze until it comes out the top. Put in the top plus so it will not come right out the bottom port. Quickly remove the tube and put in the bottom plug and tighten. Remove the top plug and top off as necessary. This process ensures no air is trapped in the gear case. It takes longer to type this than it does to do it.

Jul 15, 2014 | Boating


Changing oil in lower unit on an outboard motor.

the oil in the lower gear case in a outboard motor should be changed every fall when you take the boat out or once a year if you live where you can boat all year. when you look at the lower unit down by the propeller you will find two screws one lower and one upper. take the upper one out first and check the nylon gasket and replace if worn. put a coffee can or and oil collector under the moter and take out the lower plug. if possible do this after the moter has been run recently, but never run an outboard out of the water unless you have the garden house hooked up to ear muffs over the water intake sites!
the oil will slowly drain out. if the oil looks like chocolate milk it probably has water in it which means its leaking at the upper or lower seals and needs a pressure check and possibly seal replacemant. after all the oil is out (30 minutes or so) its time to refill it. for less than ten bucks you can but a simple device that lets you pump the oil in instead of squezzing it out of the tube. you attach it to the lower drain plug hole and the to a quart of the proper fluid for your motor. make sure you buy the oil to match your type of outboard.
pump the oil or squeze it it from the bottom until it starts to come out the top hole. make sure all the bubbles are out then put the upper plug back in with good gasket, remove the oil tube or appicator from the bottom hole and quickly relace the bottom plug as well with a good gasket.
thats it and you are good to go for the season. if you see oil leaking out the prop shaft or at one of the plugs you need to attend to that soon. tip remember chocolate milk oil or actual water means a seal leak and must be may just be a .25 nylon seal for one of the plugs is bad! any unusual noises of difficult or loud shifting can also means problems with the lower unit gears etc and its always cheaper to fix the problem sooner than later.
happy boating!!!!!!!!!!!!

on May 16, 2010 | Boating

1 Answer

I have a 1993 Dodge Dakota 4wheel drive and cant find the filler plug on the transmillion. I have found 2 plugs on back of the transfer case. Will this be the filler plugs? What kind of oil do I refi

gear box / transfer case filler plugs are about 1/2 way up the side of the unit. The lower plug (probably 1" lower is the oil level hole.. So remove the upper plug and fill till the oil runs out of the lower hole. Replace both plugs. The oil used should be a 80-90 oep oil

Nov 19, 2013 | 1995 Dodge Dakota

1 Answer

How do I check the oil level in the lower unit of a 70 hp Johnson outboard?

remove the bottom drain screw first then place a tube of the proper lower unit oil in it. then remove the top screw and gently squeeze the tube of oil and when full it will slowly come out the top drain hole. when it does replace the lower plug first then the top plug second. make sure the seals are in good shape and plan on changing the oil in the lower unit yearly for proper maintainence. make sure you buy oil designed for your particular type of motor. good luck.

May 29, 2010 | Boating

1 Answer

What oil do i use in the lower unit of a 1989 90 hp mercury outbord

go to a marine store and get lower unit gear lube. it comes in a squeeze tune and just remove the plug and squirt it in . both screws need to be out tho upper one lets air out as you push new in lower .the put upper back in first keeping oil in till you put in lower plug

May 01, 2010 | Light Outboard Motor Boat Bass Fishing...

1 Answer

How to change oil in a 2004 merc outboard 4st 9.9hp

There should be 2 drian plug screws on the right side of the lower unit. Remove both of them and let the old oil runout. After it is drained then get some new lower unit grease in a plastic tube and fill the lower unit from the bottom drain hole until it comes out of the top hole. Then you have to QUICLKY replace the bottom screw and then replace the top screw. If the old oil is milky looking then you had water in it. Hope this helps you, Jeepfxr

Jan 28, 2010 | Boating

1 Answer

Have a Johnson 130 leaking gear oil on bottom of foot and bottom full of water

What year model? Tools you will need. (1)gear case pressure tester from any outboard dealer. why buy and not build. matching the threads on the drain plugs.(1) detergent and water in a spray bottle. troubleshooting step (1) Remove lower unit from engine as if you were changing the impeller.(2) secure lower unit in a holder so you can drain oil and do visual checks.(3)remove drain plug and vent plug, drain oil(4) reinstall lower drain plug and put pressure tester into vent plug hole(5) pressurize gear case(6)with spray bottle spray gear case at all seals and joints just like you would spray a tire looking for a leak. detergent will bubble at leak.(7) if you find leak at a seal were you will need to remove drive shaft or propeller shaft you will have to buy removal tools and a Clymer repair manuel from your local dealer.(8) hopefully the leak is at the shift shaft or the drain and vent plugs so you wont have to buy special tools to replace seals.(9)if you find a crack in the case have it welded at you local outboard dealer

Nov 03, 2009 | Boating

1 Answer

I have drained the oil from my lower unit on my 180 bow rider boat. how do i put the oil back in ? all yhe oil hase drained even from the resivor in the moter compartment . it is a 3litter moter.

Not quite a car question but basically you fill it the opposite way that you drained it. You can purchase a pump at you local marine store that attaches to your quart bottle of lower unit lube.

On the end of the pumps' hose there is a threaded fitting which screws in to where the drain plug goes. leave upper vent plug out.

Pump the oil into the lower unit until it comes out of the upper vent hole.Then remove the hose from the lower unit and quickly replace the drain plug.

Wipe the excess oil off of your hands. :)

Oct 25, 2009 | Chevrolet Silverado Cars & Trucks

2 Answers

Yamaha outboard engine 4LK 6EO l 323627 HOW DO i CHANGE OIL IN

to change fluid,take out the bottom plug;should be a flat head screwdriver fitting place something to catch old fluid under the lower unit,then take out top plug,it should drain right out... then from the bottom... fill the lower unit till fluid starts to come out of the top hole then put bottom plug back in, then top plug back in and your good to go..when you have the plugs out check the seals on the plugs and replace if needed...that will insure no water can get far as the fuel mixture you can google that info

Jul 18, 2009 | Boating

2 Answers

I have a 1976 65hp mercury outboard how do i change the oil

The drain/fill hole are the same. Put a coffee can or something like that to measure the amont of oil that comes out. Check with a boat parts, or marine or sporting goods section of biggy store. They (at least to) make a pump assembly with hose and threaded end that fits into the hole for the lower unit screw. the other part of the pump fits in a gear oil quart bottle. 80 or 90 is no matter, but needs to say marine grade or suitable for marine use. Nothing special, Penzoil for sure and I think a company Lubrite plus many others make an OK oil. Anyway, put the pump in the bottle and put back in as much as drained out. The level may be marked on the side of the lower unit. If you don't get almost as much out as you put in, check for leaky seal too.

Jun 12, 2009 | Boating

Not finding what you are looking for?
Boating Logo

Related Topics:

29 people viewed this question

Ask a Question

Usually answered in minutes!

Top Boating Experts


Level 3 Expert

693 Answers

ray gallant

Level 3 Expert

44428 Answers

Fabrice Wolters

Level 2 Expert

265 Answers

Are you a Boating Expert? Answer questions, earn points and help others

Answer questions

Manuals & User Guides