Lower unit oil won't come out top vent?

[akorcovelos]

so I was winterizing my 84 Johnson 150hp, and I drained the gear oil (black as night). When I tried to refill it no fluid would come out the top vent plug, but the fluid flow would stop as if it was full? I didn't want to force it, but shouldn't the fluid come out fairly easy?

 

[mikesea]

Re: Lower unit oil won't come out top vent?

Yes it should flow out easy.Are you sure you are putting enough oil in?as you fill can you feel the slight pressure on your thumb if you cover the hole?if you put your finger over the top hole and open the bottom does the oil just trickle and then flow freely when finger removed ,its not impossible for a bit of crud to block the top hole,but you should see it,some compressed air would certainly tell you the story

 

[akorcovelos]

Re: Lower unit oil won't come out top vent?

yeah, I can squeeze the bottle of gear oil, and see it flowing freely into the lower unit, then it just stops with plenty of fluid still in the tube to squeez but nothing comes out the top?

 

[samo_ott]

Re: Lower unit oil won't come out top vent?

Weird. But get a $10 pump for the LU oil. It makes it WAY easier and less messy to change the oil...

 

[bigpoppakdog]

Re: Lower unit oil won't come out top vent?

you probably have half the tube still full of oil. By the attachment.

 

[emdsapmgr]

Re: Lower unit oil won't come out top vent?

Similar experience with same V6 gearcase on a purchased 2.6 engine. When drained the first fall, it came out thick and black, but only about half the fluid amount drained out that it should have been. When I refilled, it only took half the normal amount. The next fall, it came out milky and very black. Time to reseal the case. After the reseal, the case vented "normally" and it took the full amount of oil. My sense is that the last time the prior owner had the case resealed, that some gasket sealer must have plugged some passageway in the lower, preventing the chamber from filling fully with oil. Running with to little oil will overheat the remaining oil in the lower-turning it black quickly and could lead to premature failure. Knowing what I do now, I wouldn't run the case with less than the normal amount of oil. Perhaps time to reseal it and see if it makes a difference like it did on mine.

 

[kenmyfam]

Re: Lower unit oil won't come out top vent?

Quite simple. Check what your gearcase capacity is to how much you have put in and do the math. I have a real hard time with the "blocked" theory. Use a pump and take your time filling it. Sometimes it does feel like forever waiting for it to come out of the top, especially when doing it in cold weather.

 

[akorcovelos]

Re: Lower unit oil won't come out top vent?

I'll get one of those pumps and try again, but it really just seemed to stop accepting fluid after about 3 tubes. It seems like I put enough in the case, but not having it come out the top makes me worry.

and when I drained it it seems like all the old oil came out fine, no water in the oil at all, not milky at all.

 

[Tim Frank]

Re: Lower unit oil won't come out top vent?

If there is a blockage, you can't be sure that you have drained the gearcase properly. There is likely still old, contaminated oil in the lower unit.
With the bottom plug still out, "backflush" by pumping some oil in the top hole until you get oil running out the bottom.
Then add small amounts into the top hole until the oil coming from the bottom is clean and clear.
Then refill as specified in instructions.

 

[Silvertip]

Re: Lower unit oil won't come out top vent?

If you are in the filling process and flow suddenly stops, I'm guessing you did not take out the vent screw but rather some other screw. You cannot force a fluid into a sealed container so make sure you removed the correct plug.

 

[kandil]

Re: Lower unit oil won't come out top vent?

Or you can try to take both screws out and compress some air from the top hole and see if it will clear the passages you should have air coming out the other hole good luck

 

[fireman57]

Re: Lower unit oil won't come out top vent?

Spin you prop a little and it will take it. Had the same problem and someone here told me to do this and it worked like a charm. Felt like a fool.

 

[akorcovelos]

Re: Lower unit oil won't come out top vent?

If you are in the filling process and flow suddenly stops, I'm guessing you did not take out the vent screw but rather some other screw. You cannot force a fluid into a sealed container so make sure you removed the correct plug.

I'm sure its the correct plugs, I have done this many times on other motors.

Spin you prop a little and it will take it. Had the same problem and someone here told me to do this and it worked like a charm. Felt like a fool.

I tried turning the prop while trying to fill it, no help. I'll put some compressed air to it today and see what happens. I can hear fluid moving inside the leg, and I can hear it through the top plug, bu it just won't fill all the way up.

 

[Tim Frank]

Re: Lower unit oil won't come out top vent?

If there is a blockage, you can't be sure that you have drained the gearcase properly. There is likely still old, contaminated oil in the lower unit.
With the bottom plug still out, "backflush" by pumping some oil in the top hole until you get oil running out the bottom.
Then add small amounts into the top hole until the oil coming from the bottom is clean and clear.
Then refill as specified in instructions.

I've had exactly this happen.
Backflushing solved the problem.

 

[akorcovelos]

Re: Lower unit oil won't come out top vent?

I'll give it a shot tonight and let you guys know how it goes.

 

[kenmyfam]

Re: Lower unit oil won't come out top vent?

I'll give it a shot tonight and let you guys know how it goes.

Good Luck and let us all know.

 

[Rick.]

Re: Lower unit oil won't come out top vent?

I told a buddy to try compressed air last year and he's still trying to get me to pay for his ruined shirt. Be careful but it will blow any blockage out of the way. Rick.

 

[1946Zephyr]

Re: Lower unit oil won't come out top vent?

If the old oil drained out fine, with no milkiness, then what can be in there to create a blockage?

Don't think I've ever seen this before.

 

[Rick.]

Re: Lower unit oil won't come out top vent?

I've never worked on a leg as big as yours but on the little legs there is nothing that can cause a blockage. The gears are surrounded by the oil and there isn't any passages that could become blocked. I'm thinking it will fill just fine with a pump but it does take a lot of pump strokes before it gets to the top vent.

 

[ezeke]

Re: Lower unit oil won't come out top vent?

I've had old oil stuck many times when it is cold outside and I have read about it many times on this forum. Turning the prop while it drains and doing the same while adding new has always worked for me.