1999 Mercury 115 outboard won't turn over (powerhead issues?)

[mallardtone-man]

Hey guys I have a 1999 Mercury 115 2 stroke. It has ran good since I've gotten it with good compression when I purchased it but has always had a slight knock. I had a marine mechanic look at it for something else and he said it didn't sound like a main bearing possibly a rod bearing, might run a long time as is might mean big trouble. Last couple of times I went to start it it would not want to crank intermittently or crank very slow, noticed battery terminals getting hot. I checked the starter and the battery neither of these are the issue and flywheel cannot be turned by hand so I'm thinking that whatever was knocking may have finally given way. I've always run quick clean and stabil so I'm hoping it's not an ethanol related issue. I plan on tearing down the powerhead myself 2 assess the damage and rebuilding it as long as the block itself is intact. I have the manualI have the manual and have already rebuilt all pumped carbs impellar etc but have never really worked on engines themselves so I have a few questions I was hoping someone could help me with. Number one, does this problem sound like anything obvious? Number two when I'm tearing down the powerhead is there anything I should look for damage wise. Number three how many approximate hours should a rebuild like this take. I've heard people say between 10 + 20 I'm guessing if that's the case it would be about 15 for me maybe less.

 

[racerone]

Start with removing the exhaust cover ( 26 or so bolts ) to have a look at pistons and rings.

 

[flyingscott]

Have you taken the.lower unit off?

 

[Faztbullet]

Find a different mechanic!!!! If it was a rod bearing the crank is chit now along the cylinder that ate the spall. Hopefully it the lower unit.

 

[mallardtone-man]

Have you taken the.lower unit off?

Not yet, should that be one of my first steps? Also while on the topic of removing the lower unit, I did my impeller last year and followed a youtube video to the T as well as the steps in the repair manual, however when I went to put it back together I had a hell of a time getting the splines on the shaft to line up and then the shift linkage was off. I had to take it in to have shift linkage adjusted as I wasnt sure how to correct the problem. There was a step in the manual that said to remove the jam nut on the shift coupler then turn the shift rod coupler until the upper and lower shift rods are separated prior to removing the gear case. I was not sure what the shift coupler was and tried digging in the manual but couldn't find it. I also watched a youtube video 4 the impeller on this motor and he didn't do this step I couldnt figure out what it was refering to and they did not do that on any of the videos i watched so i proceeded without it. This could have been where I went bad but I am trying to determine what I did wrong and how I could have corrected it so I can avoid this problem in the future. I have to do another impellar soon and am worried this will happen again.

 

[mallardtone-man]

Start with removing the exhaust cover ( 26 or so bolts ) to have a look at pistons and rings.

Thats the cover on the front of the block right?

 

[racerone]

Exhaust is on the side of the block.--------Exhaust can not be behind the carburetors.