1973 Thunderbolt 500 leaking oil

[SilverSS07]

Hey guys. Took my boat out for her maiden voyage since I got done working on her! Would bog down and die with anything over idle so we putted around about 3 hours then brought her home lol. While I'm taking the carbs out I notice a little puddle on the ground under the prop of milky oil. Yay. I changed the LU oil before taking her out and the oil that came out was good. Anyway- I assume the Prop shaft seal is bad. What I'm wondering before I take it apart is that I saw a Youtube vid of a guy with a Yamaha just pulling the oil seal out with a slide hammer instead of taking the whole thing out. Would this be an option on the old Merc? BTW I have a Seloc manual.... and I'm not too impressed with it. I thought Haynes manuals were bad but this thing takes the cake lol. Thanks for any help!

 

[Chris1956]

Re: 1973 Thunderbolt 500 leaking oil

That oil could be residual from fuel. Smell it. If it smells like gas or oil it is from the fuel. If it really stinks, it is gear oil. Some say you can replace the prop seal from outside. I have never tried it.

 

[SilverSS07]

Re: 1973 Thunderbolt 500 leaking oil

Thanks for the reply. It's definately gear oil. I'll give it a try from the outside. If that doesn't work I'll try the other way lol. Spent half of today trying to get the prop off. I think it's a lost cause. Been soaking in PB Blaster for the last few days. Tried heat, hammers, prybars, 3 jaw puller and verbal persuasion to no avail. I'm debating whether I want to cut it or let somebody else do it. Guess I'll add that to the list of parts I need .

 

[mr 88]

Re: 1973 Thunderbolt 500 leaking oil

Well since the seal is going to be replaced use some serious heat to pop the prop or try a prop shop.The heat will take out the prop hub as well unless your experienced in doing that,hence the prop shop.I really doubt that you can replace that seal from the outside unless your Houdini. Chris may have more knowledge on that than me on that one,so who knows.

 

[SilverSS07]

Re: 1973 Thunderbolt 500 leaking oil

Finally got the prop off today . I read a lot on here about people having 2 oil seals around the prop. My manual only shows 1. Is that correct? Also when I look at an exploded diagram mine doesn't have all the same parts. I'm wondering if somebody changed the lower unit to a different year? Any idea how to check that? Here's one of the diagrams I was looking at.

http://www.crowleymarine.com/mercury-outboard/parts/449_20.cfm