1979 80hp mercury runs great out of water.

[ChuckGleaves]

I just bought this motor. It runs great out of the water and the cylinders each show to have compression of 140 after turning the motor over several times. I put in the water and it wants to die when you put it in gear, I was able to get it going and at about 40 mph and 2 minutes later I saw smoke and then the motor died and wouldnt turn over again. It turns over now but when it does the prop turns too? I noticed oil dripping from the lower unit but never checked it till after and it appears to be really low or empty. Could I have just burnt up a bearing in the lower unit? Clutch? Is this old motor worth fixing or should I just buy a different used motor? Thanks fot the help.

 

[mellowyellow]

Re: 1979 80hp mercury runs great out of water.

welcome aboard,<br />first step is to test compression on all cylinders.<br />an outboard can sound great running on a few cyliders<br />out of the water with no backpressure.<br />post results here.<br />good luck,<br />M.Y.

 

[ChuckGleaves]

Re: 1979 80hp mercury runs great out of water.

Each of the cyl. is showing 140. I was told a little while ago that the carbs are probably where my problem lies but I am more worried about what happened after I got her RPMs up. I just bought a new impeller for the water pump and I plan on putting that on but why does the prop turn when I am cranking the motor but still turns easy by hand. I am worried that I have either burned up a bearing in the gearbox or lower unit or that the water pump wasnt working good and I smoked the motor....at least it isnt locked up! Thanks for the advice.

 

[mellowyellow]

Re: 1979 80hp mercury runs great out of water.

you said that already didn't you... sorry!<br />running the L/U without oil can deff. fry the<br />gears. lots of these motors avail used with<br />blown powerheads and the L/U is usually still<br />good. alot cheaper than the powerhead at least.<br />if impeller went, powerhead, not L/U would go.<br />you didn't "spin" your prop hub by any chance???<br />good luck,<br />M.Y.

 

[skier]

Re: 1979 80hp mercury runs great out of water.

Ok, this is not a real safe thing to do, but, have someone hold a 2X4 (Longer the better) between the prop blades and the lower unit so that the prop can't turn and then turn the key and bump the starter. If the motor turns over then the prop is just "Free Wheeling" and that is usually not a problem. If the motor doesn't turn over then the lower unit is stuck in gear and needs some help.<br /><br />I hope this helps. Craig