Re: Overheated honda 25hp
I have a 25 hp honda outboard that overheated and melted the plastic cylinder cover . The compression seems fine and it turns over . Is it worth fixing . What do I need to check before I do more damage?
Welcome to Iboats.
I think the key thing here is determining why it overheated in the first place. I would be willing to bet the overheat is most likely due to a bad impeller. This is why we all get on our soap boxes around here and preach about the importance of replacing the impeller every 2-3 years, rather than finding out it's bad the hard way.
You say the compression seems fine. Did you actually check the compression with a compression gauge, or is this more of a gut feeling? If you haven't physically checked your compression with a gauge, I would do so as a first step. With the spark plugs out, check the condition of the plugs. Really white plugs, or plugs peppered with gray specks (melted piston) could indicate you were running lean, or really overheated it. If the plugs have a brown shade, your mixture should be fine. Shine a flashlight in the cylinders to check for scoring too. If compression seems decent (pressure on each cylinder within 10% of each other), and plugs/cylinders look good, then throw a water pump kit in the lower unit, and see if she will run. Not sure of the age of your OB, but chances are good you have a telltale on it, so you should see a nice steady stream of water coming out while the engine is running.
