Mercury 110 Help

A friend of mine just gave me an old mercury 110 (9.8 HP), the deal was if I could get it running I could use it. This is going to be somewhat of a build log because I suspect I'm going to need a lot of assistance along the way. The serial number is 4815052, I looked it up and its a 1978 motor. Where can I find new/used parts for this motor?

The motor doesn't turn over, so I'm going to have to tear it down and do a bit of a clean up then put it back together. Once I get the motor turning over I will start working on electrical. The lower unit seems to be OK, but I'm going to replace the oil in it anyways. What kind of oil should I use?

Here are some pics of it after vacuuming out all the grass and leaves

 

You can still get parts from your local Mercury dealer.

Has the engine been submerged? I ask that because of the rust and corrosion on the engine. If it has you may not want to deal with it. You could looking at a new crank, rod and main bearings, rings... etc. not to mention if the cylinders are pitted and need to be bored.

Pull the plugs and look into the cylinders, that will be a good place to start.

If it has had water inside the crank case, with the other repairs it will need, it would be cheaper to start with another engine or find one on ebay for parts.

 

The engine has been submerged, but only up to the lower cylinder. The cylinder is ok because the piston was in just enough to cover the intake and exhaust ports, however the piston is seized in the cylinder. The bottom bearing is bad and the intake/crankcase cover has a hole in it.

How do I get the seized piston out?
Will a 1982 intake fit on my 78?

Electronics are probably going to be the expensive part, the coils are bad due to overheating and the power pack needs to be replaced because the wires are shot.

 

You will probably need to soak in a penetrate and tap on it with a piece of hard wood between the hammer and part.

Unless there was a change in those models, the 82 should work. If you can get a look at the gaskets, that would tell you if they are the same.

 

Its not stripping it or finding parts its getting it apart with threads still workable. This is the expensive part about working on olde engines like this.

Take the power head off--if you can and soak submerge it in deisel for a week. This should have been done after it was sunk in water.

I would'nt get exited about this your mate is having a bit of a laugh, its unlikely you will win the bet.

 

My Merc 9.8 is a few years younger. Externally it looks identical, but under the hood everything is different, so I doubt parts for '82 will fit on a '78.

If the piston is seized, the cylinder cannot be OK. Follow Frosty's advice: diesel is cheaper than penetrating oil and works just as good (or bad).

The odds are against you!

 

I finally got the piston out by pumping in grease to get it to move and then hitting it with a BFH. The powerhead is bad, WAY too much corrosion on the bottom cylinder. So now I'm looking for a new powerhead, my local outboard repair shop doesn't have one. I found a 1977 7.5 powerhead on eBay, does anyone know if it will work? On the outside they look the same, but I have heard rumors about the ports being different sizes.