Rattling sound 1984 Evinrude 50hp

[Bailey_B]

I’m a novice with outboards but enjoy tinkering if pointed in the right direction. Cruising back to the launch last Fall going about 3/4 full speed and all of a sudden loud rattling sound occurred. Fired it up back at home. First video: Idle shows rattling at idle. Second video: Low RPM seems to make the rattle go away when running on low RPM. Any ideas?

 

[racerone]

I always say it.----Start with a compression test.----Post your numbers.----Should be around 140 + on that motor.

 

[racerone]

Next would be to check the gear oil.

 

[Bailey_B]

130psi top cylinder, 100psi bottom cylinder. As for the gear oil, oil was replaced in fall before winterization and is slightly milky already.

 

[racerone]

Take cylinder head off.-----Lucky you if it is a blown head gasket !

 

[Bailey_B]

Took cylinder head off, bottom piston has some play in it. Bottom piston’s top dead center position is about 1/16” less than top cylinder. When I jimmy the flywheel back and forth when the bottom cylinder is in TDC I can hear slight clanking. Top cylinder in TDC looks and sounds good. Something messed up with the bottom cylinder connecting rod?

 

[racerone]

Time to take it apart, I think.------Might be able to find used parts for a fix.-----Your location ?

 

[Bailey_B]

Milwaukee

 

[racerone]

Lots of good parts on " fleabay " I think/----Might need a crankshaft and a con rod.------But also inspect gears in lower unit.-----Lower units are not robust on these,----Be a shame to repair powerhead only to find issues in lower unit.----Likely needs seal kit and new impeller.