Filling 120 Merc outdrive fluid

[Rhadley]

I did my first outdrive oil change-it's a 120 model (IL4 engine), 1984. I drained the old, pumped in 1 qt into the bottom hole using the quicksilver pump kit, but nothing has come out the vent hole, which is way up on the outdrive, not on the lower unit. Manual says it takes 28 oz., but doesn't show picture of my particular OD. Am I missing something here? I don't see another plug anywhere on the unit.

 

[merc 140 pontoon]

Re: Filling 120 Merc outdrive fluid

My 1974 Merc 140 sterndrive is a I-R ("one-R") drive. My Clymer manual says the capacity is 28 fl oz. I have also been given this spec: I(120-260), R-MR-Alpha One 32 fl oz = 946 ml. I always let mine drain for a few hours, usually overnight if the outside humidity is low. Like you, I use a Merc/Quicksilver pump kit, and I carefully monitor how much lube goes in before it starts to run out the vent (top) hole. Allowing for the little bit lost to dripping and in the pump hose, I always get 39 to 40 fl oz into the sterndrive. People on other forums have agreed with this number, but I've never really gotten a good explanation why it doesn't match the specs.<br /><br />Steve

 

[Rhadley]

Re: Filling 120 Merc outdrive fluid

Thanks for the response! I guess I'll just get another bottle and keep on pumpin'. It seems strange to me that the vent hole is above the lower unit. If I took off the lower unit, would all the oil run out?

 

[Bondo]

Re: Filling 120 Merc outdrive fluid

If I took off the lower unit, would all the oil run out?

Yah, Some......<br /><br />Oil passes between the upper + lower chambers through the O-ringed Passage that you have to be careful with,when assemblying the 2 units.....<br /><br />All the Merc. outdrives hold just Over a Quart.....<br /><br />The Really Old Early 60s Mod.Os,+ the early Mod.1s Had a 2 compartment case......