lower unit vent / fill screws?

[tsutter]

Hello All:<br /><br />I took my 1966 Merc 110 9.8-hp outboard out for a spin yesterday and when I got back to the dock, and lifted the motor out of the water, I noticed what appeared to be lower unit oil, mixed with water, oozing out of what appears to be the fill screw-hole (the lower hole). Is this the fill screw hole? The diameter of this screw hole is only about 2-mm and it seems to me to be extremely small. To compound the problem, I looked above this approx. 5 inches and I also noticed a small hole about the same diameter, also without a screw. Are these the vent and fill screw holes? If so, where can I acquire replacement screws? Any additional information regarding changing out the lower unit oil and ensuring all water is out of the lower unit?<br /><br />Thanks in advance for all of your advice and other inputs.<br /><br />TSutter

 

[DJ]

Re: lower unit vent / fill screws?

tsutter,<br /><br />Yes, those are the fill/drain plugs. You fill the lower unit from the bottom. (that keeps out air pockets)<br /><br />Most of those screws have an o'ring type seal on them. Any Merc. dealer will have the seals. They are cheap. By a half dozen or so. They should be changed at least yearly when servicing the lower unit.

 

[andrewkafp]

Re: lower unit vent / fill screws?

I don't think they are your fill/drain holes, as you said there were no screws in them. The L/U would have NO oil in it and would lasted @ 5 min. And oil all over your gararge.<br />Check the holes.. are they threaded ? The diam should be way more than 2mm .. More like 5mm or nearly 1/4" in your language.<br />This is a typical L/U (Bigger, but same principal).<br /> http://www.myfishingpictures.com/img/005227.jpg <br /><br />BTW When you find the approriate holes (with screws). Replace the plastic washers.<br />Some L/U 's do have some small drilled holes here and there, but are definately not part of the sealed gearbox.<br />try here<br /> http://www.brokeboats.com/lulube3.html

 

[tsutter]

Re: lower unit vent / fill screws?

Thanks for the replies folks. As far as the diameter of what appears to be the fill hole, this is about 3/32 inch in diameter, or a shade over 2-mm. This hole is located at the front of the housing for the prop components. I haven't got a good look in to see if they are threaded, but assume they are. A mechanic at the local marina today told me that the fill and vent holes were very small diameter on older models (mine is a 1966(?)model year, Serial 2074924). What I assume to be the vent hole is located just above the anticavitation plate, also near the front. This hole appears to be only a slightly smaller diameter hole (approx 2-mm), but is also missing a screw.<br /><br />When the motor came out of the water that day, I noticed a bubbling, spewing stream of water and gray-colored oil emitting out of (probably) the fill hole. I was looking for the classic fill/vent hole setup, but the only thing I found as far as anything outside of a solid gear housing were those two holes. Is it true that old Merc models, or at least older Merc 110 models, have much smaller vent/fill holes? What is used to propel gear lube into the small fill hole? It must be an awful small tube or tip.<br /><br />Any advice is surely appreciated. Thanks much in advance for your help.

 

[roscoe]

Re: lower unit vent / fill screws?

Here is a picture of your lower unit.<br /> http://www.mercruiserparts.com/select_docs3a.asp?doc_nbr=+39562 <br /><br />Click on "GEAR HOUSING ASSEMBLY, COMPLETE(CONT)"<br />Fill screw and washer, are #10 and #11.<br />Vent screw and washer, are #12 and #13.<br /><br />Looks like they are on the left side of the engine, near the front.