2004 Yamaha 4 stroke 8 overheated

[chainsaw]

I just got a 2004 Yamaha 4 stroke 8hp short shaft mail order. It is my first outboard. I took it out of the box and secured it to my boat transom. I put in the required weight oil and and attached the gas line and then decided to test it to see if it ran. I read the manual but did not realize that I should not operate it out of water. I started it on Friday, gunned it a bit and let it idle for about a minute or two to make sure it worked. On Saturday, I did the same while showing the motor to a friend. On Sunday, I went fishing. It started fine and I started to troll. After about a quarter mile, the engine died and I could not restart it. I waited a bit thinking it was the fuel line and that I flooded it. I restarted it with no problems. I then decided to break in the engine by running it at 1/2 power for one hour. It ran fine for about a half mile and then lost acceleration and eventually died. I rowed to shore and read the manual further. I waited and started the boat again about an hour later and looked for water being sprayed from the engine. No water was coming out and I figured the engine apparently was overheating. I threaded a wire in there, it was not plugged up; I took apart the water intake near the propeller and found bits and pieces of the impeller. <br /><br />Did I screw up by starting it out of water or was the impeller or water pump defective? Are you absolutely never supposed to start an outboard out of water?

 

[fish4970]

Re: 2004 Yamaha 4 stroke 8 overheated

you never run an outboard motor without water<br />what probably hapened is that when you first started the motor, the ruber impeller went south<br />very quickly <br />this hapened because the impeller fins which are made of rubber are bent over inside a metal housing in an offset position to create a positive displacement pump<br />this ruber impeller spining at the same speed as the engine got verry hot and self distructed <br />the impeller needs water for lubrication and cooling<br />i fear that you may have severly damaged your motor<br />or at the very least greatly shortened its life

 

[rodbolt]

Re: 2004 Yamaha 4 stroke 8 overheated

Hello<br /> now its time to buy a service manual sit by the fireside and read it cover to cover. highlight the parts that you will need to remove the pump . you will need a pump kit and the housing kit. before you get tothat point though you need to do a cylinder leakdown test. most small yamaha 4 strokes have an automatic compression release device. so dont use a compression test only a leakdown test. if you have more than 12 % its time to find the damage and repair it. good luck and keep posting<br /> and always read, heed, and belive the manuals