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Outboard "rattles" at high RPM and it didn't used
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Les Lampman
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Joined: 30 Oct 2003
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PostPosted: Fri Jun 17, 2011 12:33 pm    Post subject: Reply with quote

Tim,

I don't believe you have a "transmission" problem per se. In a sense the outboard doesn't have a transmission as we know it from vehicles. There's just a pinon gear attached the the end of the vertical drive shaft which drives two larger bevel gears. Continuously I might add, so the pinion and both bevel gears are spinning any time the engine is running.

Between the bevel gears is a clutch dog. It's the thing that you're actually moving with the gear shift lever. On each end of the clutch dog there are large square-shaped lugs that engage large square-shaped lugs that are on the inner face of each large bevel gear. Slide the clutch dog to one end and it engages the pawls (or dogs) on one of the bevel gears (that's the "clunk" you hear when shifting), slide it the opposite end (with the gear shift lever) and it engages the other bevel gear. It's really a very simple and rather crude system...but it works.

So...

The two problems are related (based on the two videos). The problem isn't the lower unit (most likely) but that your shift cable (or mechanism) is out of adjustment. I've come to this conclusion based on your comment that it you were in reverse before shut down you wouldn't get the clicking in the first video (that means that the shift throw isn't even both directions). The more telling thing is the second video which clearly shows that the clutch dogs are skipping past each other in forward gear. The prop's rpm does not increase as it should with engine rpm in your video.

The most likely scenario is that normal wear in the remote or the cable is not giving you the same amount of movement for both directions. Put another way...when the remote is in neutral the engine isn't in true neutral. Typically this is just an adjustment of the cable ends (usually at the motor end but maybe also inside the remote).

When you move the shift lever out of neutral you should have to move the shift level the same distance (same degree of rotation) going to reverse or forward to start just hearing the "ticking" of the clutch dogs. I'm betting that's not the case in your situation.

Les

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timflan



Joined: 16 May 2006
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PostPosted: Fri Jun 17, 2011 7:01 pm    Post subject: Reply with quote

VERY helpful, Les. Particularly since I asked the service manager at Jacobsen's (who normally work on the boat when I can't do it myself) to watch my videos, and he came to exactly the same conclusion. This weekend, I'll try to adjust this myself.

Wish me luck!

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timflan



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PostPosted: Sun Jun 19, 2011 10:47 pm    Post subject: Reply with quote

Shifter cable has been adjusted. There's quite a bit of "play" in the entire system. I took apart the throttle control head, and that lever returns to two different "neutral" positions depending upon whether you're coming from forward or reverse. About 1/8" difference. By the time the cable gets pushed or pulled all the way back at the transom, the difference is closer to half an inch. Heck, maybe more. You can see it here:
http://www.youtube.com/watch?v=rYB3Nt7P2Sg

But I'm not sure there's actually anything wrong with it, other than it being a bit out of adjustment. When I adjusted the cable's effective length (by twisting the fitting where the cable housing enters the motor enclosure, just like adjusting brak eand shifter cables on a bicycle), so that the two neutral positions were more or less centered on the true neutral position, the trouble went away.

Protection against dropping tools and fasteners in the water:


The adjustment has been made. See the shiny newly exposed threads on the lower cable? That's what I changed.


Let me clarify...the weird ratchety clicking went away; the symptom I documented in the videos. But the high-RPM rattle is exactly the same as it has been since I noticed it in the fall.

So, now I'm thinking this high-speed rattle is still the "knocking" combustion issue we discussed earlier, maybe due to bad fuel. Or it might be some kind of exhaust issue. It actually sounds a lot like a motorcycle with a muffler that's not quite doing the job. The rhythm is just the same, but the individual exhaust events are just a bit "sharper" sounding than normal. Is that a possibility, I wonder?

In any case, I have decided to...go cruising. The motor starts and runs fine. It goes as fast as it should, and the boat runs as fast as it should in each RPM range.
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digger



Joined: 02 Nov 2003
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PostPosted: Mon Jun 20, 2011 1:28 am    Post subject: Reply with quote

Still haven't changed the plugs? Crook
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timflan



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PostPosted: Mon Jun 20, 2011 11:35 am    Post subject: Reply with quote

digger wrote:
Still haven't changed the plugs? Crook

No, but after yesterday's experiment I'm now confident that I can do this with the boat in the water, so I might as well buy a set and bring them along. The plugs in it now were new one year and 50 hours ago...I didn't use the boat much last summer with my knee injury/surgery.
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timflan



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PostPosted: Sun Jun 24, 2018 9:48 pm    Post subject: Reply with quote

Wow...what a frustrating thread. The original poster, "timflan", never came back to explain what was wrong with his engine. BASTARD! I'm having exactly the same symptoms now with exactly the same engine, and this thread is like a story without a conclusion. Sad.

So I've re-read my logs for that entire summer, and...it's entirely unclear what fixed the problem! Jacobsen's serviced the engine and discovered a bad thermostat, but my notes say "not a night-and-day difference". On the other hand, I stop writing about the rattling from that point on. So was it fixed, or did I just become accustomed to a "new normal"? I really don't know.

OK, so this time I'm going to start with the easy stuff, same as before: Replace the old fuel, and if that doesn't fix it, I'll change the spark plugs.
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South of Heaven



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PostPosted: Sun Jun 24, 2018 11:03 pm    Post subject: Reply with quote

timflan wrote:
Wow...what a frustrating thread. The original poster, "timflan", never came back to explain what was wrong with his engine. BASTARD! I'm having exactly the same symptoms now with exactly the same engine, and this thread is like a story without a conclusion. Sad.

So I've re-read my logs for that entire summer, and...it's entirely unclear what fixed the problem! Jacobsen's serviced the engine and discovered a bad thermostat, but my notes say "not a night-and-day difference". On the other hand, I stop writing about the rattling from that point on. So was it fixed, or did I just become accustomed to a "new normal"? I really don't know.

OK, so this time I'm going to start with the easy stuff, same as before: Replace the old fuel, and if that doesn't fix it, I'll change the spark plugs.


What else has happened to you in the last 7 years!?

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Pat Anderson



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PostPosted: Sun Jun 24, 2018 11:24 pm    Post subject: Reply with quote

We had a similar problem recently and took a video of the prop turning (by hand). Two people suggested a bent shaft based on the video. Turned out to be within specs but it's a thought.
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timflan



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PostPosted: Mon Jun 25, 2018 3:58 pm    Post subject: Reply with quote

Let's be clear, I only care about the "rattling at high RPMs" problem right now. The original problem, not the red herrings that followed. Smile Legmitimate though those problems might be.

OK, the thermostat LOOKS fine. Fully cold, it's fully closed.




And the spark plugs look fine, but my log indicates they have been in there since 2014, so I'll replace them despite low engine hours since then (<75 hours). BTW no jokes about me showing 3 not 4 plugs. I'd have to remove the engine cowling to get at the 4th one. I'll do that once I have the new ones in hand.



One fuel tank is nearly full of old fuel, the other is nearly empty. I'll siphon the low tank and fill it with 100% new fuel for testing, after spark plug change. Then I can do an A/B test with the two tanks to see what difference that makes. I want this story to have a coherent conclusion.
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Moxieabs



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PostPosted: Mon Jun 25, 2018 8:15 pm    Post subject: Reply with quote

Just a thought, my Honda developed a "clicking/rattle" only at higher RPMs & turned out to be play in the rear cowling latch.
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timflan



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PostPosted: Thu Jun 28, 2018 3:27 pm    Post subject: Reply with quote

Old Fuel is the correct answer.

Engine's running great with new fuel.

Also HEET fuel additive ("HEETŪ Gas-Line Antifreeze - Removes Water") helps incorporate the water in the fuel, so even the old fuel runs much better.
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starcrafttom



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PostPosted: Fri Jun 29, 2018 1:39 pm    Post subject: Reply with quote

How not to get old fuel in your boat?? USE IT MORE
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