94 merc 40 hp 4 cyl 2 strk lower unit leak

[fishcrazy1]

Hi,this is my first entry so please go easy on me. lol. Went to change gear lube in lower unit last fall before I put it up for the winter and found a lot of water in there. Too much to be condensation or something like that. I've had fishing line and stuff wrapped around the prop now and then and am assuming the seal behind the prop finally went. Don't see any oil leaking from there though. Even after sitting all winter. Bought a manual (seloc) but it shows exactly nothing about replacing the seal back there. I've looked around the net for a while and can't find anything either. Anybody got any clues as how to replace this seal? Cost? Manual? Figured if it's doable I would do it myself rather than take it to the shop. I've also read info on pressure testing the lower unit to make sure its water proof. Any ideas would be greatly appreciated. tx

 

[alcan]

Re: 94 merc 40 hp 4 cyl 2 strk lower unit leak

Hi fish<br />Your Seloc manual will tell you exactly how to replace that seal. It should explain this procedure as part of the gearcase over haul chapter. If you have done your tests and determined that the propshaft seal is indeed leaking and that is the only leak. Then just follow the steps that pertain to that operation. I don't mean to be tuff on you, but you have to do your home work. Fishing line is probably the number one culpret, next to fill/vent plug gaskets. Do the tests first both presure and vacuume.

 

[fishcrazy1]

Re: 94 merc 40 hp 4 cyl 2 strk lower unit leak

tx Alcan. I couldnt find my topic so I posted another like this. Then I flipped the page and found it anyway. lol . Is there a special pump and gauge for testing the unit? Can you recommend one? As for the fill / vent plugs you mentioned do you mean the oil fill and drain plugs for the lower unit? I bought this engine new in 95 and trolled Lake Ontario like crazy for 7 yrs . This is the first time I've had to do anything to it other than changing oil and plugs. Can't say enough about it. A touch underpowered for the boat but the dependability can't be beat.<br />tx again. Gonna go check that manual again.....

 

[alcan]

Re: 94 merc 40 hp 4 cyl 2 strk lower unit leak

Hi Fish<br /> You can buy a hand vacuume pump kit at an auto parts or tool store. The guys on this board came up with a unit from Sears the other day, this pump did both presure and vac. Thinking about checking this out myself. Anyway these pumps are not that expencive. They have many other uses also. Once you have one you'll wonder how you ever got by with out it. Like anything else they range from very cheep to what ever. Even if one cost $100. it would be easier a cheeper than tearing down a lower unit only to find the vent/fill plug gaskets were bad. Yes these are the plugs in question. I use the little hose end from the cheep gearoil pumps as an adapter for testing.