Merc 650 Leaking Oil

[billybandman]

I have a '69, 65 hp runs great, starts easy, and trolls all day long. I have noticed a nice oil slick behind the boat though. Recently I lowered the engine from being in the the "up" postition for 3 weeks while at home and a lot of, looks like gear oil, drained from the exhaust chamber around the prop. Made a small puddle on the driveway about 3-4 inchesin diameter. No lube seems to be coming from the prop shaft. I was quoted $250.00 just to pull the lower unit. I am very mechanical but have never worked on outboards. Is this most likely a seal/seals that can be easily replaced with normal tools or do I need lots or special , etc ? <br />Also would it hurt to use this like this as long as aI keep the lube topped off.

 

[coosarunner]

Re: Merc 650 Leaking Oil

My 650 did that. However, a tiny bit of what looks like oil is gas I suspect from the exhuast. Anyhow, the two seal were about $30. Easy to install, old ones should be worn and will come right out. Getting the new ones in is tricky. Try to fashion a pipe or something to hit the seals straight on over the shaft.

 

[emckelvy]

Re: Merc 650 Leaking Oil

Are you getting water in the gearcase oil? This is the best telltale for leaky seals. If there's no water in the gear oil, the 'oil slick' is probably not gear-oil-related.<br /><br />The most common problem area on older Mercs when it comes to leaky gearcases is bad driveshaft oil seals, and/or rotted away driveshaft seal area.<br /><br />As stated the seals are not that hard or $$$ to replace. The rotted away mild-steel driveshaft, if not badly corroded, can be repaired with a "Speedi-Sleeve" or "Redi-Sleeve", to name a few -- a stainless steel sleeve that presses over the corroded area to provide a smooth surface for the oil seal to ride upon.<br /><br />Like what's used on a the seal area of a worn harmonic dampener in a car.<br /><br />Also check the shift shaft oil seal for leakage as this can cause gradual loss of oil. A leaking driveshaft seal will cause a more rapid loss of oil and mixing of water with the gearcase oil.<br /><br />If you drain/refill the gearcase with fresh oil, and it's grossly contaminated after just a few runs, you're sure to have driveshaft sealing problems.<br /><br />HTH and let us know what you find..........ed