outboard engine troubles?

Question

i have a 1972 mercury 9.8 hp outboard. its is in mint condition becuase i only use it every few years. \i hadnt ran it since 3 years ago and i got gas, put in new plugs and it started right up. i left it in nuetral and let it warm up for a few minutes. it seemed fine. i started accelerating and eventually reached top speed. it went for a bout a minute then died and there was steam pouring out of the water hose (tthe one that gets rid of the water the engine alreay cooled) was hissing and pouring out steam. i let it cool for a few minutes then brought it back to my beach. when i was bringing it back it was getting power gaps- like it would go -vrromm and then it would slow down and then take off again while i had the throttle steady. any ideas what is wrong. thanks alot

its not the gas line or seaweed. just to be clear. also im pretty sure the gas mixture is right i just followed the thing on the bottle for 50:1 could it have been the new plugs?

im gonna take it to a guy who fixed the recoil before. i stopped by but he was on a call. i cant get the lower assembly off for some reason. i think its just been on there so long it just doestn want to come off.

Answer 1

From what I understand it overheated and you may have damaged the engine. The water pump is just a rubber impeller in the lower unit. See the holes, above them is the impeller. Starting an engine out of water can damage it and over time, it can dry rot and fall apart. I would remove the lower unit and inspect the water pump first and hope the damage not bad.

Answer 2

I have some experience with outboards but I would have to know more about the motor or hear it to know what's going on. The fact that it does try to turn over is good and means that you are still getting a spark to your cylinder. The other fact that you had the boat out before with the long gas line and never had problems takes that out of the equation I would think. I just wanted to make sure that you changed the spark plug. Even if you can see that it is sparking, it may not work when installed in the cylinder and is under pressure. If it's not the spark plug, I would recommend rebuilding the carb. It is a fairly simple operation and you can order a rebuild kit at the repair shop. Carburetors are finicky, and it only takes a small particle of dirt to mess it all up. Also, being a gas mix in your engine, often the gas will gum up the carb and will cause it not to function properly. I can almost guarantee that if you used a new plug and rebuilt the carb, it would be running in no time. Once you get the kit, the rebuild should only take an hour or so and you don't need any special tools.

Answer 3

You are not getting cooling water to the engine and it overheated. The pistions are trying to sieze in the cylinders. This can lead to an engine rebuild if it caused damage to the pistions/cylinders. In the best case you can fix the cooling issue and continue to run the engine. A compression check will tell how bad the damage is if it is damaged.

Answer 4

Concur with Snaglefritz. Just changed the impeller yesterday in a Mercury 7.5 for my son's Sea Scout troop. You may or may not need the whole pump assembly.
I went to a local shop and bought a made in USA part. Or, shop on-line for import parts which may or may not last. Here is a link for one source of cheap parts.

Answer 5

when you're looking at the motor from the front, there is a flat plate on the right side. remove the 8 or 9 bolts holding it on and inspect the pistons. sounds bad to me.

Answer 6

"OY" ! The water pump got weak/worn over the years, they're supposed to be replaced every two years, "YOU OVER HEATED", Check comp. on engine, I think you "Toasted" it !

Answer 7

i would have the carb cleaned on it . sometimes it can get gummed up and cause it to lunge or hessitate.