Had an odd and alarming issue on the water today.

B

Bliggity

New Member
May 3, 2020
15
Boat Info
2006 320 Sundancer
Engines
350 Mag's
The boat is an 06 320 Sundancer with 350 mags and V-Drive. 350 hours. I thought I may have felt a vibration after running the boat last time out but not enough to dig in yet. Today was a different story. We went for a longer cruise and after about 30 mins I felt the vibration all throughout the RPMS. I actually had a weird RPM jump/slippage about 20 mins into the trip. The instance only happen for about 1 second so I was aware but everything was normal again. The fun happened when the boat all of a sudden fell of plane abruptly. We were cruising at 4000 rpms. I shut down the engines and looked for anything obvious. Couldn't see any issues. Came back up and started the engines. I immediately noticed the port engine reved high and too quickly. I tested only the port side again and the engine revs nicely but does not accelerate the boat one bit. I shut down that engine and idled back to my dock for about 2 1/2 hours. Didn't know if anyone had thoughts on what this may be? I'll be taking it to a mechanic next week for an evaluation.
 
Possible failed coupler on the rear of that engine. If you smelled burning rubber, that’d be my guess as what happened. If not, you may have a failed cone clutch on that drive. If it’s dry, I’d wanna look at the drive lube for particles or burned gear lube.
 
Seapig said:
Possible failed coupler on the rear of that engine. If you smelled burning rubber, that’d be my guess as what happened. If not, you may have a failed cone clutch on that drive. If it’s dry, I’d wanna look at the drive lube for particles or burned gear lube.
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I was thinking failed coupler also. Symptoms similar to when the coupler to my outdrive went.
 
Thanks guys. I opened the engine hatch seconds after the failure and didn't notice any burning smell etc. I may head up to the boat today and look around more.
 
At this point that may be a good problem considering all the others. I was curious as how I could get under there and look but I won’t get in the water at the docks.
 
He says he has v-drives, no rubber coupler (at least not like an outdrive) or prop hub. I think first thing I would check is that the shaft is actually turning when you put it in gear. Not an expert on inboard/v-drives, but they do have a coupler on the transmission side and a keyway on the prop side. Could be a problem with either of those.
 
BillK2632 said:
He says he has v-drives, no rubber coupler (at least not like an outdrive) or prop hub. I think first thing I would check is that the shaft is actually turning when you put it in gear. Not an expert on inboard/v-drives, but they do have a coupler on the transmission side and a keyway on the prop side. Could be a problem with either of those.
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oops, I missed the V-Drive part.
Agree on your advice.

There is a triangular drive plate on the flywheel with torsion springs that sometimes fails and makes a vibration & racket before it breaks. Puts the drive in infinite neutral
 
Bliggity said:
At this point that may be a good problem considering all the others. I was curious as how I could get under there and look but I won’t get in the water at the docks.
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Don't blame you for not getting in the water at the docks..Mckinney Campground is currently closed so you might could get close enough to the swim area (beach) to be able to take a look-see on the prop..at least it's a sandy bottom and your would have to be careful not to suck up too much sand and ruin the impellers..
 
Bliggity said:
At this point that may be a good problem considering all the others. I was curious as how I could get under there and look but I won’t get in the water at the docks.
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Maybe a camera. The kind they use to look at sewers?
 
I'm going to go very professional. I found an old iPhone I'm going to take a video and place in a ziplock bag. Then I'll tape the phone to a long piece of wood. Wish me luck.
 
Anyone you know have a GoPro camera?
 
first check the trans oil to see if you have any
next start the engine, put in gear , see if the shaft turns
could also have snapped the shaft and lost the prop but with 1 1/4 or 1 1/2 shafting its remote
 
Thanks for all the input. My phone in water idea wasn’t the best or conclusive. I opened the engine hatch and checked fluid. It’s good and didn’t see any chunks. I fired up the engine and engaged the transmission forward. The forward part of the shaft that’s a brass color turned great and no issues (first picture). I looked on the rear side of the transmission, towards the stern, and found the issue, the shaft is not turning (2nd picture). I found the issue but don’t know what all this means. I would assume it’s at minimum a transmission out repair, or a transmission failure.
 

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If the coupling is turning, but the shaft is not, it sounds like a failed connection between the two.
 
I can’t quite see all the way where it meets the transmission but i can see inches from that point and it’s not spinning.
 
I was able to make a video and see that the outer part of the transmission is spinning and the shaft does not spin.
 
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