rock damage

[shat]

I have a Formula 240 BR powered by a Mercruiser 6.2 MPI with Bravo III drive. Two weeks into ownership I hit a rockpile while traveling 1500 rpm. The rockpile was in the middle of the lake (Lake patrol stopped marking the pile as bass boats kept hitting the buoy) and 1.5 - 2 feet under water. After hearing an awful grinding noise I killed the engine and raised the drive. The lower unit was gouged in places and the props were slightly damaged. The boat developed a new vibration at 1800 and 3800-4200 rpms that had not previously existed. When I took the boat to the dealer they first replaced the props with re-buit props and claimed that the boat was fixed. The problem persisted and the second time the dealer tried to fix the problem I was told that the engine had to be re-aligned and the gimbal bearing replaced. While the problem may be a little less severe there continues to be a vibration at around 4200 rpm. Any thoughts on what could be causing this would be greatly appreciated.<br /><br />PS - Dealer told me that the prop shaft was within spec.

 

[rodbolt]

Re: rock damage

what was his spec?<br /> and I have found a few bent shat couplers between the upper and lower after "incedents". also ask them the method of checking, you would not believe how many dealerships dont have a dial indicator.

 

[Reel Poor]

Re: rock damage

Could be a bent prop shaft, bent coupler shaft, damaged swivel, or tilt pins.

 

[TilliamWe]

Re: rock damage

the engine alignment and the gimbal bearing would not be the first two things I would suspect. Not after a "collision". Just think about it logically (ok, logic doesn't always hold in boats or mechanics, but play along), the two components that they are talking about are not directly connected to the thing that was struck. Props & propshafts are always my first guess when a vibration occurs after a "collision".<br /><br />

few bent shat couplers between the upper and lower after "incedents".

rodbolt, "shat" jokes aside, is that the little "collar" or sleeve looking thing that you are referencing?

 

[Northern Eclipse]

Re: rock damage

Another note is that Rebuilt props are only has good as the Guy that rebuilt them, ask the shop that sold them to have them checked and be sure that they are balanced and each ear on the props are all the same pitch.. I'v seen some rebuilt props that has just been banged out welded up and ground to shape, yet had not been balanced or pitched correctly. My cousin owns a prop shop he has seen even new out of the box props that were out. Go back to the beginning has to work performed and be sure all is well..

 

[Scaaty]

Re: rock damage

Ask to try another prop, AND run a Harbor Freight $15 dial indicator on the shaft first. Then work your way back up the drive train...

 

[lrlima]

Re: rock damage

You may also want to check the gear lube (if you havent already) just to make sure there arent any leaks. When I hit something like you did, I loosened a shaft seal and/or bearing carrier seal and let water into the lube...

 

[marunr]

Re: rock damage

Originally posted by grandboater:<br /> The rockpile was in the middle of the lake (Lake patrol stopped marking the pile as bass boats kept hitting the buoy) and 1.5 - 2 feet under water. <br />

How is it I knew you were in Oklahoma? I would 2nd the idea of having the prop checked. I bought a rebuilt one last year that was as bad as the one I was replacing.

 

[shat]

Re: rock damage

Thanks for confirming my suspicions. I have asked the service advisor twice about the replacement prop as a possible culprit and he swears that it could not be the problem. I will try again. Thanks again for the help.

 

[rodbolt]

Re: rock damage

Tilliamwe<br /> yep its the small coupler between the upper and lower. Volve calls them a Drive saver . usually if they break there is no saving the drive .<br /> but I have seen a few twist and do weired things.

 

[Boomyal]

Re: rock damage

I vote for rechecking the prop. I had a damaged one rebuilt and when I reinstsalled it and spun it by hand it looked like a reverse chrome wheel, on a '65 Chebby, in south central los angeles.

 

[Scaaty]

Re: rock damage

I bought a NEW prop for one of my outboards, and while the blades run true, the hub where it splays out on the end is off by a 1/4 inch

 

[DB Durako]

Re: rock damage

If the dealer can't get it right, ask your insurance adjuster to send it some place that will get it right.

 

[shat]

Re: rock damage

How difficult would it be for me to remove the props?

 

[Don S]

Re: rock damage

Without the proper tool, it's going to be very difficult.<br />Look at the B-3 prop wrench.<br /> http://www.properthing.com/models.html

 

[shat]

Re: rock damage

Thanks. If they can't fix the problem on the next go around I am ready to pull the props myself and have them checked.

 

[shat]

Re: rock damage

Well, I spoke with the service advisor and he now informs me that the vibration is the result of a harmonic from the motor that sets up at 4200 rpm. He claims that they tried a different set of re-built props with no change in the vibration. He also claims that they fixed the items that were rattling at this rpm and that the boat is fixed. Any thoughts? Is it normal for this type of vibration to be present? While I only had 10 hours on the boat before the collision, I do not remember experiencing the vibration before.

 

[DB Durako]

Re: rock damage

If this is a brand new boat, I would not accept the explanation. Your insurance company should make it right and you should tell them so and let them deal with it.<br /><br />You are going to have to be more firm than "I do not remember . . . the vibration."<br /><br />I have spent a lot of hours in a friend's 26-foot Crownline with the same motor and drive and there is no "haromonic" vibration at 4200 rpm.<br /><br />I don't think Formula builds boats with "built in" vibration. I would call the regional Formula rep and get them involved if this is a new boat.<br /><br />Good luck!

 

[DB Durako]

Re: rock damage

Forgot to mention---what I would do is have the dealer take me out in a new Formula of the same make and drive setup an drun it up to 4200 rpm. Then take yours out and compare it at 4200 rpm. That is the only way to tell for sure if yours is right.

 

[TilliamWe]

Re: rock damage

my 1997 5.7 Bravo 3 has a "vibration", but it's way lower than 4200rpm. And it's been there ever since I've had the boat. That said, vibration after an impact is always a cause for concern.<br />As far as the insurance dealing with it, you haven't even said you've filed a claim. Even if, your insurance company can't teach the shop how to check/repair drives. Sounds like your shop is a little lacking in their trouble shooting. Possible time for a second opinion.<br />I have been told by a shop that Bravo 3s require about $1000 worth of specialized tools(yes different than Bravo 1s), maybe your shop doesn't want to tear it down, cause they can't put it back together? It's happened before... Clinton Marine in Weldon, IL for one doesn't know how to fix a Bravo 3.