Drive oil

R

ryanr623

Chief Petty Officer
Joined
Jul 11, 2008
Messages
489
I changed my lower unit oil and tilted my drive in the UP position. I came out this morning and there was some oil in the driveway, and upon closer inspection, it was leaking out of the "upper unit" screw labelled "oil vent" that you use to fill it up. To my reccollection this has never happened.... or ive never noticed it.

It is a screw, so im not sure if stuff is supposed to come out, even if it does say vent. Could this cause water to get into the drive oil? It is above water, but obviously waves wash over it.

Mercruiser 120 mated with a Alpha One lower unit.


Pic of the Vent screw
http://www.boatingwithtr.com/Members/images/OilVentScrew.gif
 
HAV2FISH

HAV2FISH

Chief Petty Officer
Joined
Oct 24, 2008
Messages
519
Re: Drive oil

Did you replace the washers? If oil can get out, then water can get in. I would top off the oil again and replace the washer.
 
R

ryanr623

Chief Petty Officer
Joined
Jul 11, 2008
Messages
489
Re: Drive oil

HAV2FISH said:
Did you replace the washers? If oil can get out, then water can get in. I would top off the oil again and replace the washer.
Click to expand...

Thats what im thinking. An O-Ring is probably 50 cents. However, once i do this... it should not leak, correct? Just making sure im clear, so i dont keep changing o-rings in case it keeps leaking.
 
M

marcortez

Petty Officer 1st Class
Joined
Mar 21, 2010
Messages
230
Re: Drive oil

ryanr623 said:
No because the oring seemed find. Is it normal to leak out of that?
Click to expand...

No it's not normal for lube oil to leak out.

This "vent" is actually a "full" level....meaning when you have reached the capacity that drive calls for, a little excess will leak out.....until you replace the plug with gasket.

When you raised the lower unit up, the lube oil level rose, until it reached this insecure vent hole.
The gasket was not sealing it securely and some leaked out.
 
Philster

Philster

Captain
Joined
Sep 15, 2009
Messages
3,342
Re: Drive oil

ryanr623 said:
I changed my lower unit oil and tilted my drive in the UP position. I came out this morning and there was some oil in the driveway, and upon closer inspection, it was leaking out of the "upper unit" screw labelled "oil vent" that you use to fill it up.
http://www.boatingwithtr.com/Members/images/OilVentScrew.gif
Click to expand...

You're not supposed to put oil in that hole. If you do, I'd not be surprised if you have air pockets and the oil is now burping out of the vent hole.

You pump oil into the lower hole until it reaches the top hole. This helps ensure there are no air pockets.

The top hole cover should have a good gasket/ring/seal and be properly tightened.
 
JimS123

JimS123

Fleet Admiral
Joined
Jul 27, 2007
Messages
7,993
Re: Drive oil

Some Mercs have a "vent" in addition to the top level plug. (three plugs total). The vent should be removed when filled (from the bottom), but it should only be filled to the "level" plug.

None of them should have o-rings. The proper "gasket" is a nylon flat washer.

If any of them leak, replace the washer.
 
You must log in or register to reply here.
Top