clueless75
Petty Officer 2nd Class
- Joined
- Jan 30, 2015
- Messages
- 102
I recently bought a boat with a 1981 6 cyl. 90hp merc with a seized engine (knowingly, it was a good deal for the boat even without the engine). The flywheel won't turn at all - not even the slightest bit. I pulled every plug and discovered the very bottom (Cyl 6) had quite a bit of rust on the plug, and it was fairly hard to remove. Unfortunately it's the bottom cylinder and the lower cowling is in the way for me to properly inspect it but I took my phone and flashlight to try and see but the piston is near the top of its stroke so I can't see the cylinder walls. The top of the piston looks like the others, but the plug looked like it hasn't fired in a long time (when the motor did run) as it was dry as a bone with rust on top. The motor sat for about 3 years prior without the previous owner ever starting it or turning it over or nothing. I did a bit of research and bought some Sea Foam oil to squirt into the plug holes (much more in the bottom cylinder suspected of rusting) with the motor tilted all the way up so that it's almost flat. I poured some oil in yesterday and let it sit, today I put oil in and also put a socket wrench over the flywheel nut and tapped it a few times in each direction, to no avail. I squirted more oil in, and closed it up and left. What I'm wondering is am I doing everything right? I don't put much value on the motor as I can pick another one up fairly cheap, so I'm just looking to at least try to get it unseized and use it for however long it lasts afterward. I have not taken the leg off yet, but I will do that tomorrow. Is there anything else you guys recommend? I will try to oil and tap it once a day for a few weeks if nobody says otherwise. I've also heard of being able to heat the cylinder inside and it would be easier to unseize? I wouldn't mind trying that but how would I heat it up as it is the hardest to get to cylinder? Also, should I take any precautions as the Sea Foam stuff is a petroleum product and might ignite if I try heating up the cylinder? Any responses will be greatly appreciated. Thanks!
