1996 120hp Force by Merc

[ErichDahlem]

I have a small amount of gear oil leaking from the lower unit where the water ears hook up. I checked in the lower unit and the oil is clear, no water coming in. Does anyone have any idea where the oil might be coming from and what the fix might be. All advise greatly appreciated.

 

[steelespike]

Re: 1996 120hp Force by Merc

Most likely this is exhaust residue.A normal process.
This should have a gassy smell distinctly different from gear oil smell.

 

[ErichDahlem]

Re: 1996 120hp Force by Merc

No, this is definetly gear oil. There is no gas smell to it and it has that slight yellow color of new oil. I have serviced many lower units but this is the first time I ever messed with a Force/Merc. Was just wondering if this is something that ever happened to someone else before I start tearing into it. Seem's to be mostly a static leak when out of the water.

 

[eurolarva]

Re: 1996 120hp Force by Merc

I agree with steelespike. The area you mentioned is usually gas and oil mix from unburned fuel going down the leg as exhaust and usually has a frothy puss look to it. If the lower unit oil is clear it can not be coming from there. If oil is leaking out water will replace it and turn it cloudy.

 

[kenmyfam]

Re: 1996 120hp Force by Merc

I agree with steelespike. The area you mentioned is usually gas and oil mix from unburned fuel going down the leg as exhaust and usually has a frothy puss look to it. If the lower unit oil is clear it can not be coming from there. If oil is leaking out water will replace it and turn it cloudy.

And I will second that !!

 

[ErichDahlem]

Re: 1996 120hp Force by Merc

Nope, it's gear oil. Last night I wiped it down and after a few hours I had a small clear oil leak with the distinctive gear oil smell. No water mixed in, no frothy/pus color.

 

[JUSTINTIME]

Re: 1996 120hp Force by Merc

pressure check ur lower unit and then u can tell everybody what it truly is

 

[roscoe]

Re: 1996 120hp Force by Merc

The driveshaft seals under the water pump may be leaking, and the lube running out through the water intake.
But it is odd that lube would be forced out of the highest point of the lower unit.
And stranger still that water isn't getting into the lower unit to replace the expelled lube.

 

[ErichDahlem]

Re: 1996 120hp Force by Merc

Fleet Admiral, I think your right, dropped the lower unit yesterday after fishing and this time when I drained the lower unit there was water in it. Going to take off the water pump today and replace the seals, I'll let you know how it goes. Am also going to have it pressure checked. Thanks for the advise.

 

[ErichDahlem]

Re: 1996 120hp Force by Merc

Have not recieved my repair manual yet and was wondering if anyone can tell me if there is supposed to be a o ring on the drive shaft under the water pump? Pressure checked the lower unit last night and it was leaking under the water pump at the drive shaft. when I pulled the water pump impeller and plate off there was no o ring on the drive shaft just the drive shaft housing with a metal bearing around it. Anyway thats where the gear oil is coming thru. Appreciate any help. Thanks.

 

[roscoe]

Re: 1996 120hp Force by Merc

Should be the water pump base, a gasket, 2 oil seals, then the carrier assembly. Well, I guess the 2 oil seals are actually inside the carrier.

mercruiserparts.com/Show_Pictures3.asp?dnbr=809770&ivar=images/FORCE/809770/21.png&inbr=2009&bnbr=210&bdesc=GEAR+HOUSING+ASSY+%28DRIVESHAFT%29+%286+JAW+REVERSE+CLUTCH%29+%28SEE

 

[ErichDahlem]

Re: 1996 120hp Force by Merc

Got it thanks, bought the kit this morning, replacing everything only $80. Well worth the piece of mind.

 

[JUSTINTIME]

Re: 1996 120hp Force by Merc

make sure u lube the splines on the driveshaft!

 

[ErichDahlem]

Re: 1996 120hp Force by Merc

Lubed the slines put everything back together, pressure checked it and it's good to go. Thanks for all the help. If you ever need to pressure check a lower unit, the servicing hose for putting the gear oil in works great. Just keep your top plug in service through the bottom and it builds enough pressure to find the leak easy.