speedysprocket
Alex
- Location
- Chesapeake, VA
Are the yamaha impellers left or right hand threaded...?
Super Jet Impeller came unscrewed while riding?
- Thread starter OCD Solutions
- Start date
OCD Solutions
Original, Clean and Dependable Solutions
- Location
- Rentz, GA
They are reverese threaded.
Your prop was not installed tight enough. Sometimes lube and debris on the threads will make a prop feel tight before it has hit bottom. There is also some torsional instability within the driveshaft when the pump is out of the water, that is why a lose prop tends to unscrew itself.
GIL
Power In The Hands Of Few
- Location
- Cullman AL
I ran analog 4270 t/l and low idle, motor ran backwards all the time and props came loose all the time. Now I run multi channel digital, high idle, and apply as much torque putting a prop on as taking it off and therefore have not had one come loose since. 4270s are famous for letting a motor run backwards if low idle speed is present.
OCD Solutions
Original, Clean and Dependable Solutions
- Location
- Rentz, GA
Did it start and run backwards or would it bog down and swap direcrions while you were out riding? I could understand starting backwards but changing direction while rotating would unscrew alot more than just a prop i would think.
Big Kahuna
Administrator
- Location
- Tuscaloosa, AL
Your asking a guy who just yesterday did a back splat into 2 feet of water and hit his head on the river bottom....... Yes, he hit his head.
OCD Solutions
Original, Clean and Dependable Solutions
- Location
- Rentz, GA
Then i guess it's an option on the table then, wow.
Once is not a trend so we will wait and see if it happens again before we get too concerned.
Once is not a trend so we will wait and see if it happens again before we get too concerned.
FlightPlanDan
Don'tTrustAfartAfter50
- Location
- Crescent Beach, FL
Hey Boyer,
I don't know if it applies to this situation or not, but I've spun off a left hand threaded sj prop. Not so long ago.
I did a 180 nose stab and hit bottom upon re-entry.
The motor stopped so quickly that the impeller spun right off. I know .... it's a bitch to get 'em off. But it happened.
I think ... as the motor mounts broke, the coupler jammed up, (shattered) and , at the same time, stopped the shaft so abruptly that the prop spun off.
I thought I had wasted the mid-shaft, but it was o.k.
it spun off.
I guess it happens. But it is wierd.
Frank was holding the prop as I was spinning the mid shaft......."dude....it 's not moving"
The prop was spun off.....Thank goodness!
I don't know if it applies to this situation or not, but I've spun off a left hand threaded sj prop. Not so long ago.
I did a 180 nose stab and hit bottom upon re-entry.
The motor stopped so quickly that the impeller spun right off. I know .... it's a bitch to get 'em off. But it happened.
I think ... as the motor mounts broke, the coupler jammed up, (shattered) and , at the same time, stopped the shaft so abruptly that the prop spun off.
I thought I had wasted the mid-shaft, but it was o.k.
it spun off.
I guess it happens. But it is wierd.
Frank was holding the prop as I was spinning the mid shaft......."dude....it 's not moving"
The prop was spun off.....Thank goodness!
Last edited:
Here's my opinion on the issue... If the prop was even remotely loose originally and has been ridden for 6 months, there is no way it's still loose. The torque from the engine is far greater than the 13 ft-lbs that the manual calls out to torque the prop to. Your spark plugs are tightened more than 13 ft-lbs.
You said that you were troubleshooting an intermittent starting issue. My theory is the intermittent starting issue is actually caused by a sheared woodruff key or a loose stator plate. If either of these were the case, the timing could've been so far off when it finally did start that running backwards is highly possible. One quick brap backwards would loosen that prop quickly and you wouldn't even realize it's revving backwards before it twisted the prop off. I bet your real problem lies underneath the flywheel.
You said that you were troubleshooting an intermittent starting issue. My theory is the intermittent starting issue is actually caused by a sheared woodruff key or a loose stator plate. If either of these were the case, the timing could've been so far off when it finally did start that running backwards is highly possible. One quick brap backwards would loosen that prop quickly and you wouldn't even realize it's revving backwards before it twisted the prop off. I bet your real problem lies underneath the flywheel.
GIL
Power In The Hands Of Few
- Location
- Cullman AL
As the other guys already stated, it happened to me mostly during nose stabs-all is well stabbing in and then ski won't go coming out of the water because the dam motor is running backwards! 2 easy fixes, 1-raise the idle, or 2 don't let the motor completly unwind while in mid air (lightly blip the throttle one time).
There is no damage that occurs when this happens other than after 2-3 times the prop unthreads itself and you get to pull the pump and tighten it back up. Do NOT
be afraid to use as much force when tightening the prop as the same force it takes to get it loose.
Gil
ps-BK ain't lying and the bottom that my head hit was rocky. lol I am REAL sore today but had the most fun yesterday that I have had in MANY years! Great friends, great boats, great time!
FlightPlanDan
Don'tTrustAfartAfter50
- Location
- Crescent Beach, FL
I broke a lot of stuff when it spun-off.
motor mounts, pole bracket, coupler, etc,,
So, wierd things can happen.
motor mounts, pole bracket, coupler, etc,,
So, wierd things can happen.
WAB
salty nuts
- Location
- coastal GA
Bump,
This happened again this past weekend, same rider & same motor & pump setup.
This time was in a brand new Matrix SJ hull, last time was in the 97SJ. Last time the impeller came loose, it was put back on, realigned, and tourqued. With red locktite.
WTF?
This happened again this past weekend, same rider & same motor & pump setup.
This time was in a brand new Matrix SJ hull, last time was in the 97SJ. Last time the impeller came loose, it was put back on, realigned, and tourqued. With red locktite.
WTF?
Idok
F1pro
- Location
- Nations oldest muthaF+++kin city
quit presssing the reverse button !
Was anything ever changed or was it just tightened back up with red loctite? I'm not trying to be a jerk by any means but you never said anything was changed. Obviously the hull didn't cause the issue and if all you did was retorque it and hope the loctite fixed the problem, you're being way too optimistic.
- Location
- South Florida
post#5 on 10/22 and I got flamed for it. Booyah! LOL
OCD Solutions
Original, Clean and Dependable Solutions
- Location
- Rentz, GA
We are pretty sure the motor wasn't running backwards but how would one test for this anyway?
Gil's post has me curious though about the low idle thing, Scott's ski is always set to idle way lower than I find acceptable and I had to hit the start button several times after a big landings. Mine is always idled up and therefore keeping the prop spinning the right way under load. I mentioned it to him so we'll see if he changes anything for the next ride.
For the record, after the first incident, Scott used blue Loctite and torqued the impeller down with everything he had. This time he used red loctite and the same torque. He had issues with this impeller when new and had to send it out to get the threads repaired, there's a chance they are loose after rethreading or possibly just not enough engagement after some of the galled thread was removed. There is still at least 3/4" of thread but none of us have a spare laying around to see how much is supposed to be there. An inch?
If it comes off once more it will be replaced, just curious why it ran for 6 months straight and now suddenly has a problem.
Gil's post has me curious though about the low idle thing, Scott's ski is always set to idle way lower than I find acceptable and I had to hit the start button several times after a big landings. Mine is always idled up and therefore keeping the prop spinning the right way under load. I mentioned it to him so we'll see if he changes anything for the next ride.
For the record, after the first incident, Scott used blue Loctite and torqued the impeller down with everything he had. This time he used red loctite and the same torque. He had issues with this impeller when new and had to send it out to get the threads repaired, there's a chance they are loose after rethreading or possibly just not enough engagement after some of the galled thread was removed. There is still at least 3/4" of thread but none of us have a spare laying around to see how much is supposed to be there. An inch?
If it comes off once more it will be replaced, just curious why it ran for 6 months straight and now suddenly has a problem.
The only way I can think to test for the engine running backwards will be semi destructive but safe for your equipment. Look at the picture attached to get an idea of what I'm talking about.
Basically what you'll rig up is a piece of thin aluminum (maybe 0.030" - 0.050") or slightly thicker plastic as shown by the red line. The important part is that the piece be in contact with the coupler. When the coupler rotates in the proper direction the piece will slide over the coupler fingers with no problem. If the engine spins backwards, the piece will jam into the coupler fingers and either snap or bend giving evidence that the engine did spin in the opposite direction. The aluminum will last longer while the plastic will wear and probably burn up after a single ride. Metal will also be easier as you can mount it to the side of your coupler cover and bend it into the coupler as needed.
Basically what you'll rig up is a piece of thin aluminum (maybe 0.030" - 0.050") or slightly thicker plastic as shown by the red line. The important part is that the piece be in contact with the coupler. When the coupler rotates in the proper direction the piece will slide over the coupler fingers with no problem. If the engine spins backwards, the piece will jam into the coupler fingers and either snap or bend giving evidence that the engine did spin in the opposite direction. The aluminum will last longer while the plastic will wear and probably burn up after a single ride. Metal will also be easier as you can mount it to the side of your coupler cover and bend it into the coupler as needed.
Attachments
Ditto, I bought a stock waveventure with a 'locked' motor or pump for parts. When I pulled the pump, it was just an oem impeller that had spun loose and locked up against the metal couch pump shoe.
After thinking about this a little the possibilities of one specific rider causing the problems may be very plausible and it makes me wonder if that's the cause of some of my issues as well. I never have any problems with tuning when I ride my ski but on occasion when I get my ski back from letting someone else ride it, I notice that it acts screwy for the first couple seconds. I always blip the throttle as I hit water because it helps me regain control and ride out but it may be very possible that a low revving engine hitting the water vertically can stop/slow the prop while allowing the driveshaft to continue moving. I'm having a hard time visualizing it but it may have an unscrewing effect.
Last edited: