Question about lower unit fluid...

[emoney]

Changing out an impeller, I removed the drive shaft and sat the lower unit
against my tool bench and walked away. Came back to find that it had
tipped over and about 4-5 ounces of fluid had spilled out (on the positive
side the fluid was nice and fresh looking). I understand it takes about a
quart to fill it. So, does this mean I need to go get a pump and a quart
and add some, or is this a small enough amount to not worry about?
I ask, because don't I need to change out the gaskets on the two screws
when I add/change lower unit fluid? If so, does anyone carry them for
a 1983 Chrysler 50hp or are they the same as some other, more current
motor that a dealer might stock?

 

[buckwheat34]

Re: Question about lower unit fluid...

Page121 of the manual says "replace all sealing washers on plugs". I've had to remove mine several times during trouble shooting inbetween operational test and never have had a problem after 4 or 5 times removing the screw. Infact, it's the original from when I bought it in June. I do watch it for any leaking inbetween operation and storage. I just refill back to the vent and reinstall the plug. I pressure checked the unit last time and it was fine. Same requirement is called for on my ATV's, but I don't always have one available. Sure it's a good practice if they are readily available, but my opinion is that it most likely will not be a problem unless you damage the sealing surface.

Good luck,
Buckwheat34

 

[Frank Acampora]

Re: Question about lower unit fluid...

YES! You must replace the fluid lost. The top bearing is a bushing and even though it is an oilite bushing that retains some, it will starve and wear if the oil level is not high enough. The fill and vent gaskets can be reused any number of times if they are the clear or white plastic type. You just need to tighten them down Really firmly.

Almost any Evinrude, Force, or even Mercury gaskets will fit. Just go to the dealer. They generally have a drawer of different ones--usually about 50 cents each.

 

[emoney]

Re: Question about lower unit fluid...

I'll swing by and pick up a couple gaskets, just in case. One final question
(on this topic, at least), is there a difference in viscosity of the oil? What I
mean is, since I don't know what type lower unit fluid was put in there by
PO, is it going to matter what brand/type I add to it? You know, the whole 10W40 vs 10W30 type issue, does lower unit fluid come in different sizes or is it one size fits all? As to the adding back, I'm pretty sure I understand that it's just fill from bottom screw until it comes out the top? Please fix me if I'm wrong.

 

[Desertsky]

Re: Question about lower unit fluid...

I'll swing by and pick up a couple gaskets, just in case. One final question
(on this topic, at least), is there a difference in viscosity of the oil? What I
mean is, since I don't know what type lower unit fluid was put in there by
PO, is it going to matter what brand/type I add to it? You know, the whole 10W40 vs 10W30 type issue, does lower unit fluid come in different sizes or is it one size fits all? As to the adding back, I'm pretty sure I understand that it's just fill from bottom screw until it comes out the top? Please fix me if I'm wrong.

I believe my manual says it is 90w gear oil.

 

[Frank Acampora]

Re: Question about lower unit fluid...

Marine grade lower unit oil, available at Wal Mart, Auto stores, marinas, etc. It runs around 85-90 with a range depending upon the mix and if it is synthetic or not. They are usually compatible from brand to brand with the only difference being that supposedly you should not mix synthetic and regular--Don't know why.

Marine grade is the same as automobile rear end oil but has more emulsifiers and corrosion inhibitors. Automotive grade is acceptable if you never have water intrusion but if you do, the marine grade provides more protection.

 

[emoney]

Re: Question about lower unit fluid...

Thanks for the reply, Frank and that about settles it; I'll just drain it all and
replace it all. I never thought about synthetic vs. non-synthetic and I'm sure
there's no way to tell what's in there now.

Always better to be safe than sorry, right!

 

[jerryjerry05]

Re: Question about lower unit fluid...

Just make sure you don't pull the wrong drain plug.The one on the side is a pivot pin NOT a drain plug.See pic,DON"T PULL!!! Fill from the bottom till it comes out from the top.
Any Merc or OMC will have drainplug seals.If yours are the white or clear plastic you might want to change them.I have found sometimes they will seal then the next time theu won't.
You can mix synthetics with the older oils.When they first started with synthetics you weren't supposed to mix them.
I contacted Mobil One about motor oils for my motorcycle.Lot's of highway riding and high speeds.They said there would be no problems with mixing oils.
In fact they recomended the synthetic blend if I didn't want to spend the big bucks on Mobil One.J

 

[emoney]

Re: Question about lower unit fluid...

Thanks Jerry. Yeah, I had read all the "DON'T" posts about the gear screw.
I made sure it was the top and the very bottom.
So I drained and changed last night. The seals looked
to be maybe a season old (if that makes sense) so I reused them, only
because noone was open when I got off work. Is there a way to tell if they're
not good? What I did was fill it, wipe off the screws with a rag and then
watched for any oil coming out. I know that water can get in a lot easier
than the oil can get out, but how does a person know? They were round,
pliable and had no cracking?

Last question about the lower unit, I promise (fingers crossed); I used one
of the those pumps to put the fluid in, the type you screw into the lower
unit. When I removed it, the time between getting the pump out and the
screw in, obviously allowed oil to leak, is this ok? I pumped oil until it came
out the vent screw, and then pumped again to make sure. The first time I
tried, I worried too much came out so I reconnected the pump and pushed
more oil into it like before. It wasn't 2 ounces or anything, but is there a
trick to getting the screw in quick enough to not allow it to leak back out?

 

[emoney]

Re: Question about lower unit fluid...

Also, Frank or Jerry, you may remember I have another complete 50hp that
wasn't cared for as well. I 'test drained' it's lower unit before doing the one
that's mounted, and when I looked down in the gear case itself (I've also
removed the water pump) it looks to be 'gummy' and the oil that came from
it was 'milky', almost chocolate brown. From what you've said to others, I
can see that means water has gotten in there obviously. Since I'm thinking
of trying to totally rebuild the 'extra' motor, for both practice and practicality,
is the removal of the lower unit gears something that I can do? I've seen
pictures of what it looks like on the inside and I know that 'don't touch screw'
is what holds it in place, along with the two hex bolts by the prop end. Or,
does it require a special tool to reassemble? My goal in this project would
be to pull the gears and clean all the sludge out, re-grease (?), paint the
case and reinstall with new bolts/seals. If it's more than a rookie should
take on, then say the word and I'll leave it be.

 

[67Johnson6HP]

Re: Question about lower unit fluid...

The trick to filling the l/u lube is when it starts coming out of the vent, plug the vent before removing the pump. This creates an air lock and you'll lose very little lube.

 

[Frank Acampora]

Re: Question about lower unit fluid...

Removing the gears can be a Bi*ch but you can do it with regular hand tools. Drop the lower unit. now remove the two hex head screws holding the rear bearing carrier. Using a wood block, tap the carrier sideways until you can tap on the ears and push it out of the case. --better to use a puller though if you have one, so you don't bend the ears.

Remove the top front 9/16 nut on the lower unit. reach inside the gearcase and remove the 9/16 nut there. Here is the fun part: Tap apart the two halves of the lower unit. The front stud is about 8 inches long and frequently corrodes into the aluminum case making it damn near impossible to get the halves apart. If you dont separate the halves, the rear stud blocks removal of the reverse gear and the whole gear pak.

 

[jerryjerry05]

Re: Question about lower unit fluid...

You need to figure out where the water came from.It could have came from the drain/fill screws.The prop shaft or the drive shaft.You need to pressure test it.
As far as cleaning it out. If you don't want to run the risk of taking it apart.
I use a parts cleaner with the flexible hose.I prop the drive in the tub and start the flow.Move it around a couple time so the flow is different.
Then after your sure the pressure holds.Fill it and then use it. Then drain it and refill.