oil leaking from prop shaft

[sea star]

hello, i just bought a 1971 mercury 135hp. I had everything serviced but noticed while sitting in the driveway that it is leaking gear oil (greenish) out between the propeller and the shaft. assuming the seals need replacing, how big a job is this? my mechanic charges $65 an hr and i want to get an idea on how much this will run me. also, can i still run the boat as long as i fill the gear oil up? my mechanic did run a pressure test when he serviced the motor and said everything was fine, so i wondered what happened. anyways, thanks as always for any helpful info. <br /> sea star

 

[Chris1956]

Re: oil leaking from prop shaft

Sea Star, If it is really gear oil (smell it-it stinks), the bearing carrier will need to be removed, the seal changed and the carrier replaced. Should be at least $150, but it is best to get an estimate. If you run the boat with a leak, water may get in and ruin the bearings and gears.

 

[Texasmark]

Re: oil leaking from prop shaft

A '71 has a big nut that has to be unscrewed to allow the rear bearing assy to be removed. It screws into the outer lower unit housing and is almost as large in diameter as the lower unit, but very thin walled.....exhaust gas/water comes through the middle of it.<br /><br />If you pull the prop and look closely, you will see the threads on the lower unit outer housing and see the tangs on the nut where a "special Merc" wrench can grasp it. I home made one that worked ok.<br /><br />Other problem is corrosion. On an engine that old you are probably pretty corroded up so it will be a "bear" go get that nut off. once that's off the rear retainer can be pulled out of the housing and off the propshaft (leaving it, the propshaft, in the engine) and the seal can be replaced.<br /><br />Now if you are good at monkeying around, you can fish the seal out without removing anything but the seal but you have to take your time so as to not damage the shaft or seal mating surface in the housing.<br /><br />I usually drill small holes in the seal (metal part) adjacent to one another till I have a long enough slit to get a screw driver in. If I can't prise it out I continue cutting flat surface material (dikes work) till I can bend one (vertical) side in away from the outer diameter which allows the seal to be prised out.<br /><br />Take your time and be careful and you can do it.<br /><br />I would "dig it out" in a heartbeat as compared to messing with removing the retainer.<br /><br />Be sure and protect the seal from the propshaft splines when installing the new one.... a piece of paper wraped around the shaft will work and oil up the rubber lips of seal real good before starting.<br /><br />Then top off your oil.<br /><br />Mark