drive shaft housing seal

waterboy84

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Gotta replace the drive shaft house seal on the lower unit of my 94 120hp force motor. Not sure what im getting into but was told its not that hard of a job. Just wanted to get some info on what im in for and maybe alittle knowledge on what to do to change the seal. Thanks for the help
 

Frank Acampora

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The seal is in the lower plate for the water pump. You drop the lower unit and remove the water pump and impeller. Then depending upon the lower unit, you remove the bolts holding the base plate for the pump and remove it. Drive out or pull out the old seal and set the new one in. While you are at it you may as well replace the shift rod seals and the O-Ring seal for the base plate. CAVEAT: If your lower unit has the bellows type shift rod seal, do not destroy or damage the bellows--they are no longer available. You may also wish to replace the water pump impeller since you already have the pump apart--makes sense.

If you never did it before figure on spending about two hours. The lower unit is a bit heavy so if you are not at least average in strength, have a buddy help you to re-install it.
 

waterboy84

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Let me ask you something frank. The lower unit. Where it bolts to the leg there is alittle leak of some sort. I assume its a exhuast leak. But it right where the lower unit and leg meet together and bolt together. And the leak is coming from the front side where the exhuast runs down. That leak would be from the drive shaft housing seal. Correct.
 

jerryjerry05

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Why the repair?Do you have water in the lower?
You do a pressure test?
There is no exhaust in the front section.
Exhaust runs down the rear of the mid-section into the rear of the lower.
The "leak" is it drive oil?
Or possibly unburned gas/oil?

The 94 didn't have the bellows seal, it has a small seal under a retainer.


Get a parts diagram and see if your lower compares to what's supposed to be yours.
 

waterboy84

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I believe it is unburned gas/oil. I dont think there is oil in lower unit. How could i tell if there is water in lower unit. I do plan on changing lower unit oil here very soon so maybe i could tell if water is in oil when i drain it. And when i get home ill see about getting a picture of the leak and show you just where its leaking at. However let me mention when the boat is just sitting in my garage and it is not running it doesnt leak. It only leaks when motor is running. And the leak is very very little. It leaks very very slow. And like i mentioned im pretty positive it is unburned gas/oil but now it puzzles me sense you mention the exhuast runs down the rear. Is it possible it could still be unburned gas/oil leaking even though the leak is coming from the side but about id say 3 in h back from the front of the leg and lower unit
 
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jerryjerry05

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(I don't think there is oil in lower unit."no oil ????" How could I tell if there is water in lower unit)
The gear oil. What color?
Have you checked it?
If there is water in the oil the oil will be brown to light brown or milky.
Black or green oil?
What made you think you needed a new seal?

IF??? It only leaks when running??? Possible the bottom crank seal is leaking???
A carb is leaking fuel / oil and it's running down the front of the leg???

The leak at 3in from the front? It's probably unburned gas/oil.
 

waterboy84

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Ok sorry didnt get any more info posted soon. Thanksgiving holiday been a busy one. Ok so i might be alittle confused and have the rear and front of the motor backwards. Is the front of the motor the side that would face to the boat when motor is down in operating mood or is the front the side that would face out torwards the water. The way i explained it to you regarding the front of the leg/ lower unit as the front being the side that faces out to the water if your inside the boat. Yes i do have a small leak from the bottom carburator but the only think leaking is around the fuel bowl seal. I do have plans on going to boat shop and getting new fuel bowl seals for both carbs asap. Would that little leak from around fuel bowl cause this little leak issue im having with the leg and lower unit button together. I havnt been able to get a pic yet but tomorrow ill get a pic and post so you could see where the leak is at. Ill be getting lower unit oil changed asap as well and ill post pics and explain the color of it. Also i would like to ask. When changing lower unit oil i know the vent screw has to come out. Does that vent screw have a seal on it of some sort. Just asking cuz it appears oil leaks from around the vent screw.
 
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jerryjerry05

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The rear is the part that look back on the water.
Oil leaking on the vent/ ​fill screws.
They tight enough?
If so? then the seals need replacing.
It's a fiber washer and easy to get.

If you get it changed, ask for new washers.
Most don't change them on a regular oil change.
I just turn them over and make sure they are tight.

The fuel leak around the bowl: try tightening the screw on the bottom of the bowl.
Don't over tighten.

Sometimes just loosening the screw and turning the bowl and retightening can stop a leak.
It can also ruin the seal if the bowls stuck.

You can get just the bowl seal and it's an easy fix.
 

waterboy84

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Thanks jerry. So yes i was backwards about front and rear of motor. So all that i have mentioned about the leak at the front side is actually the rear. So that being said i think im pretty sure the little old leak is unburned gas/oil.
As for the vent screw i did already try to tighten it alittle more but i think im gonna just go ahead and get a new one for that when i change lower unit oil.
As for the fuel bowls. I did try to tighten them down alittle to see if the little leak would stop but it didnt. How ever i didnt try to turn the bowls and retighten. I had the fuel bowl off about a month ago when i first noticed that leak around the fuel bowl and when i took the bowl off the little seal that goes atound the bowl looked to be in bad shape. So im deffenently just gonna go get some new seals for the bowls.
 

waterboy84

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Ok so here are the pics i got and hope they will be able to show exactly where it leasks from. Right where you see my finger tip is where it will leak. The leak happens to both side in the same exact spot on both sides. Of course you dont see any fluid leaking in the pics becuz i keep all oils whip off. But if i was to start the motor and let it run for a bit id say a hour later after shutting motor off you will see fluid coming out in that crack where the lower unit and leg connect together. As you see in the pic there is no leak. I havnt started motor in about 2 weeks. It only leaks out when motor runs
 
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Frank Acampora

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I re-use cork rim gaskets all the time and I have never had a fuel bowl leak unless the original cork gasket was actually broken. There are two seals for the bolt that holds the bowl: inner and outer. The outer one seals the bowl from dripping and the inner one seals the bowl from the high speed jet. Both are required.

To reseal a used bowl against a good cork gasket do this: The bowl will deform when tightened. Take the bowl off and with a hammer GENTLY tap the inside around the hole to deform it slightly outward. When you now re-install the bowl, there will be a slight gap between the inner gasket and the carb casting. As you tighten the mounting bolt the bowl rim will press against the cork gasket and the center will deform back to the inner gasket. Works every time!

Center bolt is brass against aluminum. Snug is usually tight enough. Too tight and you risk stripping the carb casting with all the headaches that involves

Your pkotos show the parting line between the lower unit and midleg. There is no gasket or seal there and if there is a scratch or damage to either face exhaust and water can get in and out. Quite frankly, I do not remember the Mercury lower unit on Force engines BUT MERCURY engines do have a rubber seal inside the lower unit where the exhaust down tube enters it. This is to prevent this sort of leaking which is mostly a cosmetic issue.

If your Force/Mercury lower unit does have this seal and if it is missing or broken, replace it.
 
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waterboy84

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I went recently to a boat shop to get new spark plugs and while i was there i had ask them if there was a seal or gasket of some sort that went between lower unit and the leg. They pulled up a assemble diagram. The diagram that shows all the parts and pieces and how each part goes together. Well the guys diagram showed a drive shaft house seal. Now here is a issue i have that maybe you could help me figure it out. I had this boat now for about 8 months. I bought it as a running boat. When i got the boat home i looked it over and noticed the rectifier was burnt on the inside and the plastic cover on it was melted. Well one day i was out on the lake with it and boat just died and wouldnt crank back up. I ended up having to get towed back to loading dock. Well i bought new new rectifier and installed it and still the motor didnt crank. All it did was turn over. So after reading other posts on this forum i read alot about how a bad rectifier will take out the stator. So i read more posts on this forum on how to test stator. So i realized i needed a multimeter so i went and bought one. I didnt even know exactly how to use it and even where and how to begin testing stator. Thats when i figure i would sign up on this forum and sense then this forum has been the greatest. I spoke to a guy on here who user name was captain. Told him my issue and he explain everything i needed to know step by step on how to use multimeter and what wires to put to the meter probes and told me what the resistance and volts should read. Now funny part was that the next day after signing up for this forum i was gonna head out and buy a new stator and trigger. Well after talking to captain and taking in his info on how to test stator and trigger they both were good. So he pinpointed the switchbox was bad and sure enough no volts were coming out of switchbox to coil packs. So i bought a new switchbox and install and what do you know motor fired right up. Sense replacing switchbox i have had my boat out in the water twice and she ran like a beauty both times however that little leak im having worries me because i know if fluid is coming out then water has to be getting in and i dont want anything else to get damaged. Now back to the question i wanted to see if you could help me figure out. When i spoke to captain about the ignition problem i had i first told him my motor was a 99. Dont know how i came up with that but i thought my motor was a 99. He told me sense i have a switchbox ignition only models that used the switchboxes were 1990-1994. So now i know that much but im still not sure the exact year of my motor. Is there any way to finding out the exact year of my motor.
 

Frank Acampora

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As far as your year, I can not help. I am not too familiar with late model Force engine ignitions.

As far as the leak: No matter what you do water always gets into the leg. Remember that it is always sitting in the water. It is not a problem and as I said it is a cosmetic issue. As long as the lower units seals are preventing water from getting into the lubricating oil Enjoy running your engine.

Like Jerry said, water in the lower unit will either drain out as free water (from a massive leak) or will turn the oil "milky"
 

waterboy84

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Ok sounds good. Ill just not worry so much about that little leak but ill deffenently keep a eye on it. And i will be changing this lower unit oil asap. Deffenently before i put the boat in the water again and ill observe the color and if any milky look to it and good from there. I would like to thank you frank, jerry, and captain for all of yalls help and info. If it wasnt for you guys my boat would probley still be sitting in my garage broke down. Thank you so much.
 

jerryjerry05

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Cork bowl gaskets.
WD-40 as soon as you drop​ the bowl, spray wd on the gasket.

Also Take a breath between sentences. Veryhardtoreadwhenit'sallrantogether.
Just send a check :)
 
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