V-drive prop spins while in neutral

AllTideUp

Member
May 6, 2013
194
Northern Virginia
Boat Info
2003 SeaRay 380 Sundancer
Engines
8.1s - 370HP
Have an interesting issue that came up over the Labor Day weekend. Boat ran fine when I first started up sitting and in neutral everything is fine. After being under way for a bit and everything is up to operating temp, my port prop continues to spin when in neutral. Not at the same speed as when the transmission is in gear but fast enough to drive me in a wide circle.

It didn't seem to increase in speed when I increase the RPM still being in neutral but kept going once I slowed the RPMs back to idle.

When underway everything seemed fine so don't really understand what is going on with it. It happened twice over the weekend. First when we traveled to our destination and then again on Monday when we came back.

Makes docking interesting when that shaft keeps turning.......:huh:
 
I would say it's not in neutral then. Maybe not all the way in gear but if it's still spinning enough to move the boat it's in gear.
 
It sounds like the shift linkage is not adjusted or set correctly. Your transmission is never completely out of gear so you are wearing clutches while this running in neutral is going on. This adjustment is pretty critical, so my suggestion is to get the boat to your dealer or someone with ZF transmission experience sooner rather than later.
 
If it is turning slowly, it may be "windmilling" which is usually caused by hot shifting. Is it turning So much that it propels the boat?
 
Hmm, I wonder how the shifter adjustment could have changed.... Only started this past weekend...

HUMPH.. Yes it does propel the boat. will drive me in a wide circle if I just idle. It's enough to make docking a bit interesting as it continually pushes forward..
 
The cable may have stretched or something loosened up allowing the shifter to remain in gear. It is a boat and things break.
 
So spent some time down at the boat today, still here actually for a little bit.

checked the fluid, it looks fine, no burn smell or brown color.
check cable positioning, per the manual everything is correctly aligned and installed.

With that being said, started the motor, let it warm up a few minutes. When I started the motor, the shaft wasn't spinning while I warmed up the motor.

Since it gets stuck going in forward, I put the shifter in reverse, went into gear no problem no odd sounds. When I brought it back to neutral..... The shaft/prop started moving forward again!

Why would it go forward when I just went from reverse to neutral??

Went in to forward and it continued forward, no odd sounds, back to neutral and again, shaft still spins forward. However I noticed that the shaft doesn't spin forward as fast as when in gear. If in neutral, and shaft is spinning forward, I rev the motor the shaft doesn't spin any faster while the motor is rev'd up. Put it back in forward and it functions as normal when rev'd.

So I stopped the engine, let it sit for about 20 minutes and restarted, shaft began to spin in forward again without me touching the shifters. This happened over the weekend too. Seems like once everything cools it sits fine in neutral from a cold start but if I put it in gear at any time, it would spin forward once back in neutral....

I also checked the fluid levels after everything was warmed up as soon as I shut the engine down and the level looked correct...

I'm kind of stumped right now, anyone got any ideas???
 
Get out your transmission manual and read the part about setting the shift lever for either "A" or "B" position. It sounds the forward position is not set correctly at the transmission......I am not talking about t he shifter at the helm or the cables, but the shift lever on the gear box.

If you can't get a handle on this quickly, then get some professional help because you are wearing the transmission clutches when the shaft is turning in neutral. An hour with someone who knows these transmission is a lot cheaper than a rebuild kit or a new transmission.

Good luck with it...........
 
I don't understand these help me threads. You describe a problem, people give feedback, you say nope, that's not it. Like it's a guessing game for everyone and you are the host of a game show. Frank has given you some great advise, but it's like you want someone to tell you what you want to hear. Like there is some secret fix someone is going to give you the hand shake for.
Consult a professional, and hear what their diagonosis is. If you don't like what you hear, then come ask if it sounds right. The people here are awesome but dang, they are not psychics.

For the record, you are not the only one recently.
 
I forgot to give my helping thought, and not just bashing.

Start the engine, pull the affected shifter back slowly toward the reverse position, and see if the shaft stops turning at any point. May show a stretched or misadjusted cable if it does.
 
If after going thru the cable adjustments the problem still persists you can change the fluid to see if it helps. If not then the clutch plates are warped which is caused by a high rpm shift at some time. No cure for that other than a rebuild.
 
I forgot to give my helping thought, and not just bashing.

Start the engine, pull the affected shifter back slowly toward the reverse position, and see if the shaft stops turning at any point. May show a stretched or misadjusted cable if it does.

Thanks, I thought of that as well, when I tried this the prop kept spinning in forward direction until it just suddenly changed direction to reverse.


If after going thru the cable adjustments the problem still persists you can change the fluid to see if it helps. If not then the clutch plates are warped which is caused by a high rpm shift at some time. No cure for that other than a rebuild.

I haven't done any high rpm shifts but this is a used boat so who knows. I would have thought it would have had problems sooner as I have owned the boat for a year now but, who knows, this is a used boat.

I'd do as Frank suggests and get it to a dealer ASAP. A new tranny is not cheap these days.

Yeah I not looking forward to potentially replacing the tranny. I spoke to mechanic briefly on the phone and they said it could be the clutch plates or potentially the bushings. Clutch plates I can be replace with a tranny pull but if its the bushings are bad they said the tranny would need to be replaced. They said it sounds like the tranny was over heated at some point.
 
If in correct adjustment then Two things
leaking seal on the sector valve which will keep hydraulic pressure on the clutch pack; easy and inexpensive fix
warped clutches in forward clutch pack; hard and expensive fix
 
If in correct adjustment then Two things
leaking seal on the sector valve which will keep hydraulic pressure on the clutch pack; easy and inexpensive fix
warped clutches in forward clutch pack; hard and expensive fix

Hmm.. I'll have to check that..
 
Get to mechanic. Going from forward directly to reverse with "no neutral" is a good way the shearer the coupler bolts
 
Get to mechanic. Going from forward directly to reverse with "no neutral" is a good way the shearer the coupler bolts
Hmm, I don't know about that. Assuming the bolts are grade 8 or better carbon steel (150 KSI tensile strength minimum) and as a rule of thumb their shear strength is 60 percent of their tensile strength and six bolts 7/16 inch grip diameter then the shear strength would be 13680 pounds per bolt and at six bolts then say 82,000 pounds. At a bolt circle of 6 inches then the ultimate torque holding capacity would be 20,500 foot pounds and with a safety factor of 2:1 then that bolted assembly should safely hold over 10,000 foot pounds of torque. You would have a better chance of pretzeling the drive shaft or shearing the keys than breaking the coupling bolts. There is, of course, other combined forces like the propeller shaft trying to push the coupling apart but this is incidental to the rotational shear. Not in consideration is the friction coefficient between the coupling halves which will increase the torque capability slightly. This is all predicated that the bolts are properly tightened and within their elastic range.
 
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