2003, 8 HP, 4 Stroke, Johnson, Vibration

[JohnnyBoy1963]

I recently bought a short shaft 8 HP 2003 Johnson 4 stroke outboard as a kicker motor for my 18ft Lund. It was used for 1 season and I bought it with a warranty that lasts until 2007. It vibrates more than I expected at most speeds. <br />My typical trolling speed for salmon fishing is 2.5 - 2.9 mph (top speed for this motor on my boat is about 5 mph.) It vibrates such that a couple times the motor cover became loose and I had to step into the splashwell to re-attach it. Not something I want to have to do period, especially on a big lake in rough water. Has anyone had this problem, is this motor known for high vibes? Is there anything I should look for. Can any vibration balancing be done ? <br /><br />I am thinking of going back to the marina I bought it from to either try to ge it fixed or trade up to a new 9.9 hp Johnson. In hopes it will be smoother. Any experience with a 2005/2006 9.9 hp 4 stroke Johnson ? <br /><br />Thanks,<br />JohnnyBoy

 

[DJ]

Re: 2003, 8 HP, 4 Stroke, Johnson, Vibration

IS the propeller nicked up? If so, it will add to the vibration. Also, the wrong pitch prop can lug the engine.

 

[JohnnyBoy1963]

Re: 2003, 8 HP, 4 Stroke, Johnson, Vibration

No, the prop is like brand new. It vibrates more than i'd like to think it should even at idle without the prop turning. Also, all mounting bolts are tight and everything inside the engine looks good. Seems like the flywheel is out of balance...maybe Johnson does not take care with balancing ..alignments etc ?? I dont know , i expected to have a very smooth running engine when i bought a 2003.

 

[Xcusme]

Re: 2003, 8 HP, 4 Stroke, Johnson, Vibration

Are you sure it's running on both cylinders?? It's easy enough to sort out. While running, pull a plug wire off it's spark plug ,then replace. Do the same with the other plug wire. The one that does not change the rpm's , is not 'hitting' (little or no spark). Since the motor is under warranty, let the marina fix it.

 

[JohnnyBoy1963]

Re: 2003, 8 HP, 4 Stroke, Johnson, Vibration

Yes it's running on both cylinders. It does work. I am looking for anyone with experience with this particular motor or similar vintage smaller Johnson 4 strokes. Either my motor has a problem, or they are all built that way...with poor vibration and balancing specifications..ro loose tolerances ..or whatever in this case resulted in a rougher running piece of rotating equipment. I expected a small 8 HP relatively brand new motor to purr like a kitten.Its not even close , the cover has vibrated loose on several occasions and actually off once. I've only run the motor about 8 -10 times so far. <br /><br />Thanks for any help I may receive.

 

[Dhadley]

Re: 2003, 8 HP, 4 Stroke, Johnson, Vibration

If it idles that bad in neutral I'd say something was definately wrong. I've only ran 1 8 hp 4 stroke and I remember thinking that if I had traded a 9.9 2 stroke for it, I'd not be pleased. It wasn't the greatest but I don't remember it being that bad.

 

[NZ 2]

Re: 2003, 8 HP, 4 Stroke, Johnson, Vibration

If it idles that bad in neutral I'd say something was definately wrong. I've only ran 1 8 hp 4 stroke and I remember thinking that if I had traded a 9.9 2 stroke for it, I'd not be pleased. It wasn't the greatest but I don't remember it being that bad.

I've got the same motor. Our mechanic has checked it out and could see nothing wrong. It idles fine, but vibrates so much the the cowling comes udone and it will make anything loose down the back of our 20ft runabout rattle like nothing else. I'm considering installing anti vibration mounts with a lower auxillary bracket to resolve the problem, or buying a new Yamaha 8hp four stroke. Would be a shame though, as we have a 150 Johnson and the motors kind of match at the moment.

 

[boobie]

Re: 2003, 8 HP, 4 Stroke, Johnson, Vibration

This post is 6 yrs old. Read the rules at the begining of the forum and please start a new one.