Water in gear unit

[kat-a-tonik]

Ok, I have a FD20C Johnson 20HP, Its getting water in the gear unit, I know there is a seal behind the prop as well as an O-ring, a seal on top of the lower unit around the drive shaft and the little gaskets on the drain and fill plugs, is there anything else that might be the culprit as well

 

[racerone]

The o-ring on the shift rod is often overlooked .--It is a major leak point on these older motors.

 

[kat-a-tonik]

Ok thanks racerone while I have it torn down I will replace that O-ring as well, anything else, anyone

 

[Expidia]

I just changed the lower gear oil on a 25 merc yesterday . . Pheew, no water! . Not like my 40 had last season when I changed the gear oil. Had to bring it to the shop for new seals. Tip: a tube of gear lube is cheap enough. Use the boat for a few houra and then drain it again. Double checks that you installed the seals correctly and they are holding. A shop uses a pressure tester. I do this even after I have my merc shop replace the seals. $5 for the lube and 15 min work is cheap insurance IMO.
Also wach out for fishing line getting behind the prop as this can rip your new seals real quick.

 

[hardwater fisherman]

There is also a tiny seal on the pivot pin. Part number 0307853.

 

[boobie]

When it's all done take it into a shop and have it pressure tested. No guess work.

 

[Expidia]

Actually, I did not have to drain all the gear oil again to test the seals after they were repaired. I just did this a few min ago to my 40 hp. Take out the gear oil fill plug. Then unscrew the lower one until oil starts to drip out. If the seals are leaking again water will drip right out first. After I re-tightened the drain plug I then I squirted a little gear oil into the top filler plug just to top it off again.

 

[kat-a-tonik]

Ok, hardwater fisherman, if I remove the pivot pin to replace the seal on it am I going to have any problems with anything inside the gear case moving and not being able to get the pin back in correctly

 

[bspeth]

Not if you don't try to shift it.Pressure test that pup to see where its leaking from before you go changing stuff.Put 8 lbs in it (not with a compressor) and listen. Then squirt 409 on the area and you are in business.

 

[kat-a-tonik]

Would I be able to pick up a preasure tester at my local auto parts store, we have two boat shops in my area but neither one wants to fool with it because it is such an old motor

 

[racerone]

Sad when shops tell you that.----A pressure test is the same whether it is an old or new motor !!!

 

[kat-a-tonik]

yeah racerone, if you ask me its bad business practice

 

[bspeth]

get a gear lube fitting and attach it to a hose then attach the other end to a gas pressure gage from home depot,one that only goes to 15#.The test gage will have a Schrader valve on it .Easy just takes a little time to run around and get the stuff.

 

[kat-a-tonik]

Ok, trying to keep this post current, I am going to try to preasure test the lower unit this afternoon I will post my results, bspeth you said spray the area with 409, is this to see if there are any bubbles to confirm a leak

 

[racerone]

Little bit of dish soap and water works just fine as a leak detecter.

 

[kat-a-tonik]

Ok so I got a pressure tester rigged up and tried to do a preasure test, I say tried because the lower unit wouldn't even hold air, I could here it leaking from the lower port were the screen is, so am I right to guess it is either the upper seal of the lower unit or the O-ring around the shift lever

 

[bspeth]

drop the lower,and continue your pressure test,it will comfirm the source for you.If you cant find it spray your tester as well.

 

[benjiboy]

If all the seals are still in place, you could always place the lower unit in a big clear rubbermaid tub filled with water and look for the air bubbles.

 

[kat-a-tonik]

Ok I did the preasure test today, I submerged the lower unit in a tub of water, the first time was without the driveshaft because my tub wasn't big enough, of course the bubbles came from the driveshaft hole, after realizing that wasn't the right way to do it I found a bigger tub and put the driveshaft back in, I preasurized it again and the bubbles came from around the shift lever.

 

[racerone]

The o-ring on the shift rod is often overlooked.--There is a special tool to remove the bushing .----Or the o-ring can also be replaced without removing the bushing.--Most folks will say that the latter --" can not be done "