'84 merc rattles?

[jonboat2]

I don't know how to ask this question so i'll provide facts about my engine.

Half trottle is all it gets to then it starts to studder like if its running out of fuel. If I keep it studdering it'll eventually die, maybe 1 or 2 seconds. I just went

through the carb because the choke solenoid was sticking so mind as well cleaned the carb.

This only happens under load. Got home and hooked it up to the water hose and it was fine until half throttle where there was little studdering.

(engine off) If I move the flywheel it makes noise like a bad rod or something.

Sounds like the noise is coming right after the engine or powerhead (still new to outboards) What is there that could be worn or out of alignment that is

causing this problem. I'm still going to check the carb again just to be sure. Which weight

Sorry for the long post. Just wanted to go fishing, then this happens.

 

[Mi duckdown]

Re: '84 merc rattles?

Start with compression and spark first. or visa versa.than report back. Cheap checks.

 

[jonboat2]

Re: '84 merc rattles?

Spark is strong and compression is at 90 and 95. cold engine

35 hp 2 cylinder. Left that out in the first post.

 

[canoemang]

Re: '84 merc rattles?

while off.. put it in gear.. move the flywheel and see if the noise is made just before the prop moves.. if it is you might have some slop up the where the drive shaft slides into the crank or even in the LU.

 

[jonboat2]

Re: '84 merc rattles?

while off.. put it in gear.. move the flywheel and see if the noise is made just before the prop moves.. if it is you might have some slop up the where the drive shaft slides into the crank or even in the LU.

I did this and it didn't make noise. As soon as i moved the flywheel the prop turned.

 

[CharlieB]

Re: '84 merc rattles?

Remove the spark plugs, rotate the flywheel by hand until the top cyl piston is getting near top dead center, Turn the flywheel backwards just a few degrees, use a wooden dowel or similar object to reach thru the spark plug hole and push on the top of the piston to see/feel if the piston will move ANY distance at all before the flywheel begins to turn.

Do NOT hit the piston and do NOT use anything sharp or pointed as it could leave a mark/damage the aluminum piston.

Repeat the test on all cyls.

If any movement of a piston without corresponding movement of the flywheel/crankshaft, highly suspect a badly worn bearing, on a connecting rod, requiring dis-assembly and repair before causing irreversible damage.

 

[jonboat2]

Re: '84 merc rattles?

I probably do have a bad bearing. I heard a little tick right before the flywheel moved. Man, well thanks for the help fellas.

 

[Faztbullet]

Re: '84 merc rattles?

The 35 and 40 hp are bad about snapping crank below the upper bearing....