lower unit does not fill

[amishboy]

I have a 1973 Mercury 650 (65hp). I am trying to put lube into the lower unit. I have both drain/vent open and using a pump to put oil into lower drain. At a certain point no more oil will go in but it is not coming out of the vent hole. Also seems to be quite a bit of oil running back out when I try to cap the drain. When I try to add oil to the vent, it just runs back out. Motor is verticle. Any ideas and does anyone know how much oil this lower unit should hold?

 

[rodbolt]

Re: lower unit does not fill

alot of those old mercs had a flush port,looks just like a vent but it goes to the cooling system.
are you positive the vent is out and not the flush plug?
pictures would help.

 

[Mi duckdown]

Re: lower unit does not fill

That is a new one on me. There should nothing restricting the oil from coming out of the vent.
I guess I would blow air with a compressor from the lower drain(unit drained) to see if there is a blockage. Got nothing apparently.

 

[rodbolt]

Re: lower unit does not fill

I would NOT blow compressed air if I suspected the vent was either restricted or not removed.
if the flush plug was removed and not the vent both compressed air and an oil pump can and will pop seals out of place.

 

[amishboy]

Re: lower unit does not fill

Tried it again. When I opened, about 4 oz of oil drained out. Put in about 2 full pumps and the oil started blowing back, however a small trickle started out of the upper opening. Trying to attach picture. The lower cap on the left is metal, the higher cap is plastic. There are no o-rings on either.

 

[Mi duckdown]

Re: lower unit does not fill

rodbolt. I agree. I assumed the vent plug was removed Not the flush.
The vent plug is just above the cavitation plate, I believe on the starboard side. for that model as are most of them. PICS

 

[Mi duckdown]

Re: lower unit does not fill

Amishboy. there only 2 screw/plugs on the lower unit, the unit that bolts to the mid section. Do you see where that splits?

 

[amishboy]

Re: lower unit does not fill

Trying to resize pic to post. New computer, crappy technology. Now have to leave. Tornado warning in NW Ohio

 

[Arkman]

Re: lower unit does not fill

I'm not certain but i think the vent screw should be metal. On mine around that year its a metal vent/drain plug and a plastic flush screw. I'd agree that you maybe removed the vent screw instead.

 

[amishboy]

Re: lower unit does not fill

Metal lower screw on left, upper plastic on right. I don't see any other possible ports on the lower unit.

 

[Arkman]

Re: lower unit does not fill

amishboy- I could be totally wrong, cuase i'm not certain i understad what I'm seeing but I think there should be one more screw...at the very bottom of the lower unit. Mine is hard to see unless you really get under it. Not totally sure on yours though. Its worth a look. Check out part number 32 on this page. Do you see that in yours? Sorry if I'm way off here. I'm just looking at that photo and maybe I dont understand it right.

 

[Jacket4life]

Re: lower unit does not fill

You are not looking at the fill hole. Arkman is right. The fill hole is at the BOTTOM of the LU. Glad to hear you have the pump. Raise your motor and look at the bottom of the LU toward the front, and you will see the plug. Your LU should hold over a pint of fluid. I have the same yr model Merc 500, and it holds just under a pint.

When you get done with this, do yourself a favor and find a Merc manual for your motor. It will save you LOTS of time and trouble!!!

Best of Luck!

 

[amishboy]

Re: lower unit does not fill

Bingo! Found the fill hole. At the bottom, angled down like all fill holes should be. I wonder if the Mercury engineers graduated from the same school as the other Mercury engineers (Nasa)?

Thanks for all the help!

 

[Arkman]

Re: lower unit does not fill

Glad you found it!