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70 hp johnson outboard wont go full speed


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How did your mechanic determine you had internal damage from overheating ? As posted if the compression is good the engine is potentially salvagable !Do you known that the engine was overheated ? Commonest causes are a blocked intake , usually from a plastic bag blocking the intake or an impeller that was not changed at a regular interval which would disintegrate and pieces would block the water passages ! The wrist pins on the pistons would go or the needle bearings on the crankshaft would go ! Turning the motor by hand may give an audible sound , then it is probably " game over " ! If not it should start then there would be no doubt with the knocking sound !

Again how id your mechanic decide that you had internal damage  ?

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Yes I know it overheated.  My alarm was going off for a while to get back in to shore. That being said. U can see that the motor got so hot it melted plastic connections  on some of the wires laying on the topic the motor.  And the seam where the block meets the intake has apparent  melted paint. I am getting a second  opinon Thursday from  the johnson dealer. Ill get back to you guys then. At this point ive started to look at used motors in case the motor needs an overhaul for sure and its over my head in diy or cost . Well see . Thanks everyone 

Edited by Tim G.
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I finally  got my answer to the overheated engine. I took the head off to inspect the pistons and the sleeve  on cylinder 2 has twisted . I was  told by the dealer that the block is now junk.  I've already  got another motor installed on the boat this weekend . Thanks for everyone's help. As I said before I was hoping for good news but this is by the worst case scenario  

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