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Gears blew up!

Spoiledrotten

Spoiledrotten

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Last Labor Day, I hit a submerged log up the river. It destroyed my new 4 blade alum prop, and bent the prop shaft. I put it in the shop and they replaced the shaft and sold me a SS prop.


Well, this labor day, we went for a day trip. The motor started making an odd rattling noise. I pulled into a nearby boat ramp and checked the prop to see if anything looked wrong. Nothing. A guy was standing close by and stated that it sounded like I should trailer it home, so I took that advice after he was nice enough to haul me back to my house to pick up my truck/trailer. I took it to the shop and found out that some of the teeth were broken off of the gears. Now, this mechanic is going to replace the lower section from the drive shaft down. 


He told me that it was most likely from a stress crack that was overlooked when the work was done a year ago.  :angry:


Needless to say, the guy that sold me the boat, and did the original work, had a few words. Mainly because he totally supports his mechanic/son. He said they went over those gears under a fine light. Right!
 
Ouch. That sucks. Was this an insurance claim? You might be able to tie the current damage back to the original date of loss. Technically if it was a stress fracture originally missed it was damaged when the other stuff was. Worth a shot.
 
Bummer, Randy. 


So, what you're saying is that the engine may have had some previous damage before you hit the log? I'm not very mechanical, but is there any chance the gears were damaged recently rather than last year? Probably doesn't matter at this point however.


That aside, I've always been told that if you boat in an area that is prone to prop strikes (rocks, logs, etc.) having an aluminum prop might save you from more extensive repair bills than a stainless steel unit. 


Good luck... 
 
Michiman said:
That aside, I've always been told that if you boat in an area that is prone to prop strikes (rocks, logs, etc.) having an aluminum prop might save you from more extensive repair bills than a stainless steel unit. 
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+1. Agree completely.
 
Exactly why I am an aluminum prop guy.  Lakeliving might be giving you some excellent advice spoilerotten
 
Flo Torque Hub on mine 

 
Very good advice. 


I don't believe there was any damage before the log impact last year. The mechanic thinks that this might have been caused by the gears being stressed by the log impact, thus taking a while for the damage to show in the form of a broken tooth or teeth on the gear set.


Something else I'm needing to do is to lower the deductible on my boat from $1K down to something less painful.
 
Hey Randy, I misread your post. When you said "last Labor Day", I thought you meant two days ago. As such, my response was probably a bit bewildering to say the least. I understand now... :)
 
I'm sure your mechanic can write on the estimate that it was related to the impact last year to satisfy the adjuster(providing that is the case). I don't condone or tolerate insurance fraud so hopefully your mechanic is ethical about it. And if it is in fact not related, looks like another claim or a self-insured event. That part will be up to you and the repair bill.  
 
Link said:
Exactly why I am an aluminum prop guy.  Lakeliving might be giving you some excellent advice spoilerotten
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I had a brand new 4 blade aluminum prop on last year when I hit the log. Not sure how much more damage a SS prop would have done unless it broke the motor off of the back of the boat. :D
 
Unless they did a dye-pen inspection, they could have used a 1000 watt light, and it don't mean sh**. Many metal fractures/stress can't be seen with the naked eye. A dye-pen kit will typically show them though. Truthfully, a chipped gear could go for years or days before destroying others.
 
Thanks Semper. They did not and will not admit that they did anything but the right thing. I really have a problem now, taking my boat to someone that can't admit mistakes. We are all human, but when you can't be honest about it, then there is a problem. When I talked to the owner of the dealership, and he said that they checked those gear really well, I wanted to tell him that I didn't expect him to say, "Oh dam, we forgot to check on the gears, we just put a prop shaft in and called it good". But that's what happens when you have a dad owner looking out for his son mechanic. Can do no wrong, even at the expense of losing future business. Too bad there's not another Bennington dealership close. I'm just glad there's a certified Yamaha mechanic within 10 miles of me.
 
I understand your frustration with the situation. But I do understand the other side also. I know many mechanics that would not try to save the customer some money by reusing parts,even if they look good. And this situation is exactly why. If you had gone through insurance,I would have demanded a complete lower end after a severe strike like you had a year ago. May be cheaper in the long run if the use a rebuilt and get a warranty to boot!
 
They are getting the complete lower unit from Yamaha. The mechanic stated that he could rebuild if I'd like, but the rebuild comes with a 90 day warranty, where the new comes with 1 year. Since my motor is a year old and comes with a 3 year warranty, I would think this lower unit would still be warranted for the next two years. Thoughts?


I tidbit of good news is that I found out that my deductible is $500 and not $1000. After this is completed, I'm moving that down to $250 on the deductible. It will only raise my premiums about $3.50/month.
 
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My "NEW" complete lower unit is being installed today! Now, to go back through the 10 hours of break in. :(


Oh well, almost like starting with a new motor.   :)  


$2500 minus my deductible is what the insurance company is paying. Can't complain. Toys cost money.


I'm keeping the old parts, so hopefully, I'll have spares if needed in the future. 
 
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Good to hear your going to be up and running soon! And even better news about the insurance taking care of the lower unit. And I would think the warranty would cover the factory new lower unit. But why a 10 hour break in? I've replaced I/O lower units before and never had a break in period. <_<

Spoiledrotten said:
My "NEW" complete lower unit is being installed today! Now, to go back through the 10 hours of break in. :(


Oh well, almost like starting with a new motor.   :)  


$2500 minus my deductible is what the insurance company is paying. Can't complain. Toys cost money.


I'm keeping the old parts, so hopefully, I'll have spares if needed in the future. 
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The 10 hour break in is for the engine itself.  Proper heating and cooling to seat the rings properly, among a few other things I am sure.  Never heard of a mechanical device like a lower unit needing a break in.
 
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I hope this shines some light on the subject.


The lower unit needs break-in period for the gear teeth to complete the hardening process in sync and under proper load with each other. This wasn't the first time I'd heard about this. The ring and pinion gears need to work together at slow and interval speeds to complete the process. This process will create shavings from the gears during the initial running together. 


I had higher gears put in my Jeep TJ a couple of years ago, and the mechanic told me not to tow anything for the first 500 miles for this same reason. I know that the motor has to break in the pistons/rings and other things, but the new gears need that as well.


This link if for auto gears, but a gear is a gear to me.


https://www.ringpinion.com/TechnicalHelp/contentframe.aspx?filepath=~%2fcontent%2fparts%2fringandpinions%2f%2fnew_gear_break-in.inc


Just a small excerpt from the link I'm sharing:


"In order to make them run cooler and quieter, new gears are lapped at the factory. However, they are not lapped under the same pressures that driving creates. The loads generated while driving force any microscopic high spots on the gear teeth back into the surface of the metal. This is called "work hardening". Work hardening is similar to forging in the way that it compresses the metal molecules into a very compact and hard formation. This can only be accomplished if the metal surfaces are lubricated and the gear temperature stays cool enough that the molecular structure does not change. If the temperature of the metal gets hot enough to change the molecular structure, it will soften the surface instead of hardening it." 


Here's another bit of advice from another source about new lower units, whether it's new on new boat or new LU on old boat:


http://www.crowleymarine.com/support/tech_articles/lower-unit-sterndrive-break-in-procedure.html


"Note: Gearcase assemblies are shipped without oil.

  1. Fill unit with manufacturer's required gear oil to recommended level.
  2. Adjust RPM at idle to manufacturer's specifications.
  3. Proper shift adjustment is essential.
  4. Jumping out of gear: If the unit will not stay in gear, the clutch dog has probably been rounded off. Rounded clutch dogs are caused by, but not limited to, improper shift cable adjustment, inadequate shift travel, idle RPM too high, and/or shifting too slow. Rounded clutch dogs are not covered by warranty.
  5. Avoid full throttle starts.
  6. Do not operate at constant speed for extended periods.
  7. Shift into forward gear a minimum of 10 times during break-in, with moderate engine speed after each shift.
  8. Do not exceed 75% of full throttle during the first 5 hours of operation.
  9. During the next 5 hours, full throttle should not be maintained for long periods."
 
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Oh, and BTW, the wife and I took the boat out for a few hours, yesterday afternoon. I got through the first 2.5 hours, then the lightening started up around us. Boat ran good!
 
1Blderbob said:
Good to hear your going to be up and running soon! And even better news about the insurance taking care of the lower unit. And I would think the warranty would cover the factory new lower unit. But why a 10 hour break in? I've replaced I/O lower units before and never had a break in period. <_<
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Did I answer your question with the post above? Make sense?
 
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