1980 Merc 50 4 cyl lower end oil leak

[pspencer]

I was given an old fishing boat by a friend and after two uses discovered what looks like black gear oil dripping down from behind the prop. I removed the prop, retaining washer and carrier bearing retaining nut to see whats up. The outer prop shaft seal looks dry, with the oil running along the inside of the cavity at the 6:00 position. Could this be un-burned fuel or is the large o-ring at the rear of the bearing carrier assy the culprit. Very uneasy about removing the carrier bearing assy and prop shaft due to lack of specialty tools. Is this a repair that is easily completed in the home garage?<br /><br />Thanks,<br /><br />Paul Spencer

 

[ob]

Re: 1980 Merc 50 4 cyl lower end oil leak

Paul you'll need to determine whether it is accumulated two cycle oil or in fact lower unit lube.A smell test should verify as lower unit oil has an unmistakeable aroma.Also recommend you drain lower unit and inspect condition of oil.If you determine that it is in fact lower unit oil it is likely as you suspect coming from a leaking "o" ring on the carrier assy.Repair is not too difficult as long as you have the proper pulling tools to remove.This is where a service manual would be of value if you are not familiar with the procedure.

 

[pspencer]

Re: 1980 Merc 50 4 cyl lower end oil leak

Thanks for the reply. <br /><br />I pulled the assy out by hand, believe it or not it did not require a puller. Replaced both shaft seals and found the o-ring more or less baked onto the carrier. Put it all back together and will have to wait on the carrier retaining nut ( detroyed the other one getting it off). The manual states the nut should be torqued to 210 ft/lbs. Now I am no engineer, but that number seems excessive. <br /><br />Also, should the prop shaft have some spring to it if pushed in toward the lower unit.<br /><br />Thanks for the help.<br /><br />Paul Spencer

 

[ob]

Re: 1980 Merc 50 4 cyl lower end oil leak

Paul , I did a half baked search and so far all I come up with is around 60-70 ft lbs torque on the propshaft nut.I assume this is what you are refering to as it looks like it contains the lower carrier as well.In any case 210 seems excessive to me also.

 

[pspencer]

Re: 1980 Merc 50 4 cyl lower end oil leak

Thanks for the advice and help.<br /><br />Paul Spencer<br />Dallas, Texas

 

[pspencer]

Re: 1980 Merc 50 4 cyl lower end oil leak

One more question.<br /><br />Are there places that rent or loan marine specialty tools similar to some of the auto parts chains practices?<br /><br />I need to reinstal that carrier bearing nut somehow.<br /><br />Paul Spencer