1970 Merc 50h cracked lower end - this bad, how bad is it?

I have a '73 Silverline 15' with a 1970 Mercury 500 50h outboard. Hit a submerged limb and thought I had just bent a prop. When I went to change it, the entire shaft came out (without unscrewing. Closer inspection revealed that the bottom of the housing was cracked at the threads. Know it's bad, but how bad? I probably need to sell the boat, but don't know if I should fix this and then, or note it to a buyer in the listing, or just sell the hull w/o motor and part the motor. Also, maybe the wrong forum, but any thoughts on a reasonable sell price? Don't want to end up as a note on the "funny Craig's list" list...

Re: 1970 Merc 50h cracked lower end - this bad, how bad is it?

There are places that can weld the crack and i have seen a tool that can rethread it, just depends on if someone wants to take it on.

Re: 1970 Merc 50h cracked lower end - this bad, how bad is it?

Real bad, as in "time for a new gearcase". If you impacted hard enough to dislodge the bearing carrier, chances are the bullet is bent, and welding and rethreading wont do the job. Unless the prop shaft is perfectly aligned, the gearset will be in pieces in no time. Look around for a used gearcase, or try to sell the boat without the outboard.

Re: 1970 Merc 50h cracked lower end - this bad, how bad is it?

I have a '77 Merc 500 and I had a cracked gearcase just like you, mine was caused by the previous owner not changing the lower unit oil when it got water in it and it froze in the winter. My crack was right on the threads and the nut and prop pushed out.

The aluminum casting is real thin where it is threaded. I have heard of people welding those but I would be worried about the aluminum shrinking and the threads no longer being good. I also know of people drilling those and pinning the lower unit nut in place. Either way IMO is a temporary fix, you're looking at a new gearcase or a replacement lower unit. I bought a replacement lower unit for $150 on Ebay.