1973 Mercury 500 50hp

by S Newton
(Broken Arrow, OK, USA)

First time boat owner. bought a used 1999 Landau DX18 pontoon for me and my son to rebuild from the ground up (both boat and motor).

It came with a 1973 Mercury 500 50hp that seems to have an issue when I hit 4k rpm. It slips in and out of gear. The rpms will spike to 5.5k and will lose all propulsion and then it drops back down to 4k and moves again.

We were all but given this boat so we are OK with learning as we go. I'd like to take the lower unit and motor apart but I am a novice with outboards. I've looked for a service manual online and I'm not finding anything that I trust to download or buy.

Any recommendations on a good source? Links would be much appreciated.