Seized Mercury 5HP Outboard

[SandyBoat]

I?ve aquired a 2001 Mercury 5HP outboard, which looks in pretty good condition, but is seized (or at least the start pull cord won?t pull out). The motor has been in storage for at least a year, but was supposed to be working fine went it last ran.

I?m thinking of first of all examing the pull cord mechanism to make sure that is not to blame, then pulling the spark plug and perhaps putting WD40 or penetrating oil in the top of the cylinder to try and free the piston up.

Any suggestions or advice welcome.

 

[corm]

Re: Seized Mercury 5HP Outboard

Hi,

I would use Kroil or some other penetrating oil rather than wd40.
Otherwise your off to a good start. I have had to tap the top of the
piston with a wood dowel and a small hammer to free them up before.
You do not want to dent the piston dome. This only works if the piston is not at TDC or BDC.

 

[SandyBoat]

Re: Seized Mercury 5HP Outboard

Thanks for the reply - I'll see what penetrating oil I can get locally.

Does anyone know if once I've got the recoil unit off the top of the motor (having never done that before), if there is something I can get a spanner on to try and turn the engine over?

 

[corm]

Re: Seized Mercury 5HP Outboard

Hi,

I have not looked at one but I think it has a ring with some slots in it that you could put a bar through to try to turn it. It may not be real strong. There is always the flywheel nut or a belt style flywheel holder.
Be careful if you use the nut, you can strip the threads. I've even seen a broke crank. If it is stuck that hard you will need to tear it apart to re ring it anyway.
It is new enough that I am sure it has a head gasket. So you could always pull it off to do a visual inspection. Once it is loose you can rock the flywheel and see if the rings wiggle in the piston. if they do you maybe can just run it. It all depends on how why it is froze up. If it took a swim then the bearings maybe rusted if it was not cleaned out and heavily oiled asap after it happened.

 

[SandyBoat]

Re: Seized Mercury 5HP Outboard

Well today I took the recoil unit off the top of the motor and found underneath on top of the flywheel is the spool for the emergency starter cord. There was some play in that, when I wiggled it by hand, so I put the penetrating oil in, and kept on wiggling that spool and managed to get a spanner on the flywheel. The long and the short of it is the engine now turns over and is no longer seized

I'm going to treat the engine to a new spark plug and fresh fuel then try and start the thing. The piston sounded just fine as it moved up and down the cylinder, so I am pretty confident the motor will run.

Thanks again for the advice.