Outboard "rattles" at high RPM and it didn't used

Hi Tim,

Good video. Sorry I can not help with the noise. I have the same year Johnson 90. Do you have the tach with the digital display that shows engine hours and fuel information? I have had a problem with mine.

I hope someone can identify the noise.

Steve
 
SeaSpray":3qntjws9 said:
I have the same year Johnson 90. Do you have the tach with the digital display that shows engine hours and fuel information? I have had a problem with mine.
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Yes I have that digital display. Seems to be working fine. Maybe start a separate thread on that, and let's discuss.
 
timflan":21pscz2b said:
OK, I haven't had a chance to give this much attention, but today I ran the engine, I switched between the two fuel tanks and ran it at a variety of throttle settings. I heard the rattling when I ran it above about 3000 rpm, but not at lower RPMs.

But now I think I have new, helpful data. Video data:
Tim's YouTube video

Now I could'a SWORN I checked the rotation of the prop in neutral, with the engine off, right after I got unstuck when I was up the river last fall. It's the first thing I do after running into debris or touching bottom. Check the prop, examine all the blades, make sure it turns freely and on-axis.

It's virtually impossible to imagine that I did NOT do this back in October. So what happened? Perhaps I was simply not looking for a clicking sound. My focus would have been on the prop, the rotation, and the ease of movement. Maybe I just didn't notice the clicking.

Or maybe it's something that's gotten worse since then?

I just don't know. Experts, please watch my little video and tell me what you think. Thanks!
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The sound in the video is absolutely normal! AB-SO-LUTELY. What's happening is you're turning it in the opposite direction that the remote is positioned to and the sound you're hearing is the clutch dogs slipping over the engagement pawls. If you turn it the other way it shouldn't turn at all (the pawls will engage).

That sound should only occur when the engine is in gear. If it's happening in neutral then the shift cable is out of adjustment (or at least the shift throw is not correct for some reason).

Les
 
I could not have said anything better, Tom. That was great for me. I think I need to go to sleep now.
 
Ok Tim - I have no idea what the issue is with your engine.... but I was ROFLMAO on Tom's video link :D
 
Les, I talked to Tim and I believe that the boat was in neutral when he was turning it. he removed the prop and all was in order. It has to be, as you noted, something in the gear box or the shift cable.
Which is over my head and should be looked at by a shop.

for the record I did not drive down today. got stuck a the survey of my folks boat. spent hour trying to figure what the yard did to kill all the start batteries when they put it on the hard. they left the key for the start circuit on all week. My folks are using this yard for the first time on a recommendation by me via another c-brat and so far I'm not total impressed. taking longer then stated and some of the work is less then par. I crawled under the boat to check the grates for the cooling water pickups. they where well painted. even the mass of clams clogging the grate had a nice coat of blue paint on them. Its all in the details people :wink:
 
I agree totally with Les. It is possible that when the motor is tilted, it is pulling on the cable -- perhaps the cable is breaking, stretching, or an end is pulling loose. If the motor is truly in neutral, and then that specific noise will be gone. Most noises will be "masked" unless you have the engine cowling (cover) off. Even then it is often tough to hear where specific noises are originating. I would change the plugs for sure -- often, preignition will give rattling noises -- that would be more likely when you are under load or high rpm conditions. That can happen due to deposits on the plugs that start "glowing" which causes the engine to fire without the actual spark ignition. Fuel injector problems can also cause erratic engine combustion, but those are more expensive to change than replacing plugs. You can also tell alot from the color of the plugs electrodes and porcelain. Good luck, Ron
 
I'll add here that for me there are likely two different issues here.

The sound in the video I've heard hundreds of times and it's a normal sound from the lower unit (unless the shift cam is truly in neutral then there's something out of whack).

The noise when running is likely a different issue unless the shift throw is so far off the clutch dogs are slipping.
 
Les Lampman":2zn7d58p said:
I'll add here that for me there are likely two different issues here.

The sound in the video I've heard hundreds of times and it's a normal sound from the lower unit (unless the shift cam is truly in neutral then there's something out of whack).

The noise when running is likely a different issue unless the shift throw is so far off the clutch dogs are slipping.
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Yeah, I'm starting to think that the high-rpm "rattling" is unrelated to my transmission issue. I really appreciate all the feedback.

Here's a new video that may provide more info:
http://youtu.be/QtKxdK_22UI

Interesting note: When the engine is shut down in neutral, if it was engaged in reverse last, prior to neutral + shutdown, the prop spins freely, with no noise. THAT'S the behavior I'm accustomed to, and since my last bit of maneuvering while docking or any other time is almost always a bit of reverse thrust, it's entirely possible that I would NOT have encountered this clicking sound when I spun the prop by hand previous times.

Again, there's a likelihood that the "rattling" at high rpm is completed unrelated, and I may or many not have some sort of transmission trouble.
 
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
 
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!
 
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:
IMG_0826-Copy.jpg


The adjustment has been made. See the shiny newly exposed threads on the lower cable? That's what I changed.
IMG_0827-Copy.jpg


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.
 
Still haven't changed the plugs? :crook
 
digger":3kjtgu9m said:
Still haven't changed the plugs? :crook
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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.
 
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.
 
timflan":3vjet58l said:
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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What else has happened to you in the last 7 years!?
 
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.
 
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. :-) Legmitimate though those problems might be.

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

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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.
 
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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