340 Drive Train, Part 2

[Tacoma290]

While on plane this weekend, I noticed a new vibration appear suddenly (boat ran great all season). I throttled down as fast as I could, but just before I got down full idle, I heard a bang. Popped the engine hatch and determined that the starboard transmission turns, but it is as if the shaft sheared or the prop is gone. Got back to my slip on one transmission. Our water in the Northwest is cold, so I am having a diver get pictures before I get up on the hard as soon as possible. I will provide an update here once I know more.
My past boats had outdrives and I came to really dislike them (always deteriorating in salt water, I can't work on them, and the most complex part of the boat is in the water).
This 340 is new to me this year. I had a previous thread '340 Drive Train' where the port side received new thrust bearings, strut and shaft seal as a result of a bent strut. So this is second time I will be on the hard for v-drive work in a season. I had hoped that issues with the transmission would get better with v-drives, so perhaps I had set unrealistic expectations. How often are you guys replacing shafts and other running gear?

 

[dtfeld]

Shafts shearing? Not very often, but not unheard of. Most of the time it because of a prop strike, but it could be metal fatigue for a number of reasons, including a previous minor strike that started an out of balance condition, a stress crack or riser and eventually it let’s go.

If you hit something, the good news is it’s likely an insurance claim. Make a claim and follow insurance co instruction.


Sucks, but it’ll get fixed.

 

[Tacoma290]

Thanks for the reply dtfeld. That does make sense.
I have an old sheared shaft from this boat when it was owned by the Previous Owner sitting on my desk in front of me. Will know more about what I face tonight when I get pictures from a diver.
And the boat will be pulled on Saturday am.

 

[dtfeld]

Thanks for the reply dtfeld. That does make sense.
I have an old sheared shaft from this boat when it was owned by the Previous Owner sitting on my desk in front of me. Will know more about what I face tonight when I get pictures from a diver.
And the boat will be pulled on Saturday am.

Are they from the same or different sides??? Where did they separate. Where is important...might point o a bent strut, bad cutlass bearing or other item that needs to be addressed.

One is unusual, two...hmmm.

 

[Tacoma290]

So the news from the dive was not good. Prop shaft sheared just aft of the strut. I am missing the portion of the shaft and the propeller, which will need to be replaced. Seems like an odd failure, considering both props were just redone in December. These photos are of the end of the shaft at the failure.

On its way off the boat, the prop glanced off the hull.

 

[dtfeld]

Looks like it started in the key way, and failed from there.

 

[Motoguy2158]

The shaft had been cracked for awhile. The beach areas, smooth cross sections were the original fracture point.
The rough areas, shows corrosion ( discoloration) and fretting which is where it finally broke.
It appears to me that failure started in the area of the key, the dark greenish area to the left of the key slot, looks to be mechaincal damage from a tool (puller) while pulling the prop. It looks like that was a fracture point. You can see the lighter bluish green areas were beginning to corrode over time. The finger that sticks out was the last part to break.
Im not an expert but have worked in rotating equipment for years. I put my money on damage to the shaft from
a previous repair. Shafts, especially when they have high loads and are subject to vibration need proper key fits, fit to shaft and proper nut torque. Any damaged areas, like dings, dents (mechanical damage) can create a stress riser or fracture point. Either way this ain't gonna be cheap.

 

[Tacoma290]

The shaft had been cracked for awhile. The beach areas, smooth cross sections were the original fracture point.
The rough areas, shows corrosion ( discoloration) and fretting which is where it finally broke.
It appears to me that failure started in the area of the key, the dark greenish area to the left of the key slot, looks to be mechaincal damage from a tool (puller) while pulling the prop. It looks like that was a fracture point. You can see the lighter bluish green areas were beginning to corrode over time. The finger that sticks out was the last part to break.
Im not an expert but have worked in rotating equipment for years. I put my money on damage to the shaft from
a previous repair. Shafts, especially when they have high loads and are subject to vibration need proper key fits, fit to shaft and proper nut torque. Any damaged areas, like dings, dents (mechanical damage) can create a stress riser or fracture point. Either way this ain't gonna be cheap.

I think that's a pretty good bit of analysis. I had concluded that it was either from a bad prop pull (mechanical damage), or a manufacturing defect (a few other 340s of this era had similar issues). Either way, this is not an insurance issue.

 

[Tacoma290]

Yesterday, with the help of a good mechanic (thanks Bill Collector!) we got the prop, shaft and coupler pulled from the good side (port), and am taking to a local prop shop to replicate.

 

[Tacoma290]

Shafts: The original shaft was an alloy of Aquamet 19. Turns out the good port shaft was Aquamet 22 (better grade). So I will be matching.
Propellers: The shop needed to know the specifics of the existing prop, since they were hoping to match and there were no make/model markings. The prop set appeared to have been original which would be a Teignbridge Z85 series 4-blade nibral. The size of the needed starboard is 18x21 RH. [Note this is different than the port which was 18x21.5 LH to address the opposite turn of the transmissions]. It may be easier for me to locate it for them.
Strut:A new issue is the strut which appeared to have been exposed to electrolysis, and the condition was not ideal (the aft-most 1.5 inches on the bottom of the strut sounded hollow compared to the rest of the strut). Sourcing a new strut is not easy in our current times (Sea Ray has none, FP says 4-6 weeks lead time, and Marine Hardware who owns Algonac say 6-8 weeks lead time).

 

[Tacoma290]

Update:
Shafts: New stbd shaft of AQ22 is complete. Port shaft was already upgraded to AQ22 and was good, just needed polish.
Props: New stbd Prop is ready for pickup. Port prop is trued. Both are now Class 1.
Strut: New stbd strut was cast at a foundry in Arlington WA, using the old strut as a way to make the mold. Should be ready for pickup next week.
Shaft Seals: New lip seals are here.

So for potential new 340 buyers, in addition to possible water intrusion to the bow fiberglass, I would add to check the shafts for the grade, check them for how the keyway was made, and scrutinize alignment very closely.

 

[Motoguy2158]

Glad you're getting it sorted out. Hopefully you can get it wet pretty soon.

 

[Jon Paul]

If the damage, crack, was caused by a bad prop pull, there likely would be insurance coverage. Depending on your specific policy. Take it from a insurance guy. : )

 

[dtfeld]

I would make a claim. Your already biting the bullet, so it can only help. Dock neighbor (I think a similar year/model) had the same issue last year. $12k all in.

 

[vandal]

2005 to 2007 the shafts that seray put on those boats were to hard alot of them broke call searay to find out if they were recalled.

 

[Tacoma290]

2005 to 2007 the shafts that seray put on those boats were to hard alot of them broke call searay to find out if they were recalled.

Good suggestion. Sadly, no recall.

 

[Dabble]

Hope you’re back in the water soon. Glad you got it fixed.

 

[Misterhelms]

Question - I bought an 04 340 down in North Carolina and drove it up the ICW and eventually offshore to New Jersey. Along the way I hit bottom once at about 1100 RPMs and on two separate occasions felt the boat and possibly the prop come in contact with something underwater. The first time was around 1100-1200 RPMs and the 2nd time around 2300 RPMs. I haven’t felt any vibrations but my paranoia has gotten the best of me when it comes to the sounds I’m hearing from the engine. Should I go ahead and haul the boat out? I was thinking of maybe getting it detailed and the bottom painted as it’s due / but kind of wanted to wait I til the end of the season to do all of that. Thoughts or advice?

 

[Tacoma290]

Hope you’re back in the water soon. Glad you got it fixed.

Yes, I checked in with the Foundry today, and the new strut was cast this morning and is still hot! It will be machined next week. Will be splashing soon!

 

[Tacoma290]

Question - I bought an 04 340 down in North Carolina and drove it up the ICW and eventually offshore to New Jersey. Along the way I hit bottom once at about 1100 RPMs and on two separate occasions felt the boat and possibly the prop come in contact with something underwater. The first time was around 1100-1200 RPMs and the 2nd time around 2300 RPMs. I haven’t felt any vibrations but my paranoia has gotten the best of me when it comes to the sounds I’m hearing from the engine. Should I go ahead and haul the boat out? I was thinking of maybe getting it detailed and the bottom painted as it’s due / but kind of wanted to wait I til the end of the season to do all of that. Thoughts or advice?

Does the engine or transmission sound different to you now? If you don't don't feel anything and don't hear anything, I would suggest having a diver check if you want peace of mind. It is pretty cheap insurance, and most take pictures and videos if you are there with them.