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Mercury 7.5 hp outboard 8057545 & Up (AUS)

Itsallgood

Itsallgood

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I'm a bit confused, I have some mechanical knowledge when it comes to motors and such but do not like going past my comfort zone when I'm not sure on something. I brought a small 12ft alloy dinghy with a Merc 7.5 hp around 1980-82 a few months back, had some issue with the motor runinng an it pumping water, there finally sorted out an fixed. Today i decided to do a gearbox oil change an watched light'ish brown sludge ooze out the bottom drain hole, I flushed it with some WD 40 an got it pretty well cleaned out.. now the problem i have after filling it with outboard gear oil thinking that's whats meant to be in it - after watching a few youtube videos on similar aged/size mercury motors, and them using outboard gearbox oil. Ive come back to this site, looking at the parts list for my outboard, thinking i might replace the drain/filler screws an it says - part #36 (10-79953) SCREW, (.375-16 x .250), GREASE FILLER HOLE / part #37 (12-20260) WASHER, GREASE FILLER HOLE SCREW. I did read while trying to find out correct way of doing the oil change, some outboards they used grease in the gearboxes instead of oil.. an with what come out of this outboard.. it looked more like runny grease oozing out than a milky oil.. The filler screw parts above mention grease Filler screw... If anyone on here has any knowledge on this, any help would be appreciated.. i hate the thought of something going bang an me rowing miles on end to get home.

thanks in advance
 
People use Lubriplate 105 gease on gearboxes that have bad seals (like yours) that allow water to enter. The grease tends to reduce the damage water does better than oil.

Jeff
 
Thank you for the replies Jeff an Kim.. no oil has leaked out any of seals yet since yesterday (prop' seal or filler/drain holes), so I might put in it a drum an let run for awhile, then do another oil change an see if there's any water in it an go from there. with the screws i wanted to replace, that's because some ones butchered the heads of the screws in the past, an it was a bit hard to get them out. Thank you again, appreciate the info :)
 
I spoke a bit too soon i think lol.. it didnt leak yesterday after filling it with gearbox oil an running for awhile, still hadnt leaked over night/this morning early when i got up an checked, bit later after the suns come up , heated the leg up - warm to touch (its summer here in Australia - hitting 40c/103f plus last few days) i go back out an have another look just now.. leaking out the prop seal.. might have to do the grease thing now. Does anyone have any idea how much grease should be getting squeezed in there, or would it be a pull it apart an pack it in job? I'm sure like with oil it needs to be a certain amount or will have pressure problems
 
Thanks for replying again Kim.. I'd say should be able to get the prop off, going to have to order that part now :) fingers crossed I'll be out catching some yabbies (similiar to crawfish) soon lol.

PS, thanks for chasing that part up for me mate!
 
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I have a few more questions if anyone can help...

1st question, that Lubriplate 105 grease some people use in the gearboxes with bad seals... is that pumped in via drain/fill hole, or is the gearbox pulled apart an it gets packed in? I'm concerned about over filling it if i do try it. Ive had a look for that Lubriplate 105 grease in a few shops around the place (here in Australia - reputable auto shops) and told they've never heard of it, but I'm sure there has to be another brand/same thing available here.

2nd question, I found some Morey's heavy duty oil Stabilizer an put that in straight unmixed, it seems to have stopped the leak, but I'm wondering if its to thick an will harm the gearbox? (I have not tried running it yet) I'm thinking if grease can used, surely this thick oil would not be any worse to use than grease?

Ive ordered a prop seal for this Merc, but knowing my luck, it'll be mid to late Jan' by the time i get it an it'll stuff up all my plans of going away for a break/camping trip with this boat over this holiday break.

Thanks
 
Remove both plugs and squeeze it in from the bottom 'til it comes out the top.

Jeff

PS: People have run leaky LUs that way for decades!
 
Thanks for replying/helping Jeff, is appreciated. plan on buying a pdf manual from this site very soon.. I did a compression test today an im thinking as old as this little thing is and as rough as it looks, psi was 120 on top, 118/119 on the bottom, should have lots of life left in her :)
 
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