Damper explosion

[kman]

Yep, Mr Mayhem payed me a visit. Full throttle getting on plane at about 4500 rpms. .......kaboom! Then silence. Large holes in the bellhousing, and shrapnel everywhere. Worse part is that some of it ripped through the wiring harness. Hoping the engine and trans are ok, but will have to go through everything I guess. My biggest challenge at this point is figuring out how to get the thing out. Any ideas?

[mikeg205]

Good the dog house protected the crew and passengers

Sent from my SM-G955U using Tapatalk

[dtc]

Sorry kman! I replaced mine a few years ago and would be happy to talk with you to try and share what I can recollect. PM or email if you’re interested and we can exchange numbers. Bottom line is that you can absolutely do it with basic mechanical skills. Might as well go for the rear oil seal while you’re that deep into it.

[tomski2001]

Never seen that before! Did it just let go, or were there some strange noises beforehand? It's a mess, but could have been a lot worse if the shrapnel had escaped.

[ttu]

man that stinks. how many hours? didn't they improve the damper plate at some point. don't remember what year that was.

[kman]

Yeah, i worked on it a couple hours on Sunday, and it's about ready to come out. Still looking for ideas on how to pull it though.
It made no wierd noises beforehand, running smooth and BOOM. Only had around 270 hours on it too. Only
had 6 people on the boat and about 2k of ballast loaded up. We normally just surf and have around 2900lbs of ballast. According to Indmar all 8.1 liters came with the HD damper plate that is rated to 625lb/ft of torque. The stock 8.1 has 500lb/ft. I guess surfing all the time really puts the load on the damper plate.

[Huckelfin]

Yeah, i worked on it a couple hours on Sunday, and it's about ready to come out. Still looking for ideas on how to pull it though.
It made no wierd noises beforehand, running smooth and BOOM. Only had around 270 hours on it too. Only
had 6 people on the boat and about 2k of ballast loaded up. We normally just surf and have around 2900lbs of ballast. According to Indmar all 8.1 liters came with the HD damper plate that is rated to 625lb/ft of torque. The stock 8.1 has 500lb/ft. I guess surfing all the time really puts the load on the damper plate.

Would it be fair to think about the root cause of this failure in addition to fixing it? The chosen springs are meant to dampen the vibrations to a certain design case, so why did it blow apart? You didn't mention springs rattling around before the failure & it doesn't seem like it's old enough to just say that years of use caused some things to degrade.. is something else in the driveline providing abnormal stress?

IE: if this is replaced, what are the chances it just blows apart again? Maybe just overthinking it, surfing loaded down causing the problem.

[robadele]

Something is not right there for that to go out at 270 hours. Did you have a prior prop strike? Any serious drive line vibrations? Are you running a prop that causes a lot of cavitation? I'm assuming it is out of the water now and you've seen the prop and was not a prop strike that killed it.

[kman]

No prop strikes or driveline vibrations at all. I'm running an acme 1285 (14.5x14.25) now, but i have the original prop that came on the boat, and there's not a mark on either one. I checked the alignment when i got it back in 13 and again in 18. No issues. Only thing i can think of is big block torque, lots of surfing with a lot of weight, and a high torque prop.
I guess I'll just have to pull the starter every year and inspect it with a bore scope or something.

[Huckelfin]

No prop strikes or driveline vibrations at all. I'm running an acme 1285 (14.5x14.25) now, but i have the original prop that came on the boat, and there's not a mark on either one. I checked the alignment when i got it back in 13 and again in 18. No issues. Only thing i can think of is big block torque, lots of surfing with a lot of weight, and a high torque prop.
I guess I'll just have to pull the starter every year and inspect it with a bore scope or something.

Take some pictures of what damage you discover and maybe it will point to the true failure mode. Could be as easy as having been that some bolts just worked themselves loose. Unless you have significant power upgrades, I doubt the 8.1 being higher torque is a significant factor. Surely the engineering work was done to ensure the selected plate is capable of it. Also just the fact its not a widespread issue.

[kman]

Can't really say if it's a wide spread issue or not, however, my friend has an 05 x10 with the mcx that is used mainly for surfing, and his damper came apart at right around 300hrs. It didn't explode like mine, but several of the springs came out and is was cracked when we pulled it. Also, the guy i know at indmar, said mine was the third catastrophic failure of a damper in an older boat he had heard of that weekend. I'm thinking these older boats were designed for skiing and wakeboarding, and not really up for surfing duty with extra weight, and low pitch props. Just my opinion.
I'm hoping to get it pulled this weekend and see what all the damage is.

[kman]

Update: We got the motor out using a lift in the back of my truck method. Very nerve racking, but actually worked pretty well. Just took our time and moved slow. Getting it back in is going to be the bigger challenge.

[kman]

Update2:
For those interested, i sent the wiring harness to Technical Services in Indiana, and they were able to fix it up. They are a member on this board.

The problem I'm running into now, is what damper plate to install. It seams i have 2 choices - the original, or the supposedly upgraded 885203. I ordered an 885203, and its a very flimsy POS. Its 30% thinner than the one that came out and i can bend it with my bare hands. No way that's going in there, so i sent it back. The one my buddy got to replace his was 885201, and it is much beefier than the original, but it's unavailable now. Anybody have any ideas?

[Tilemule]

Is yours a 26 spline? If yes, they have one on this list that should work for you. . . .

https://www.hardin-marine.com/c-277-...ve-plates.aspx

[kman]

I actually sent them an email about that plate, and instead of trying to work with me to see if it would work, they responded with a smartass comment. They basically said they don't know anything about it except the dimensions. I did get the part number, and found it somewhere else cheaper, but i haven't got it yet. Don't know if it's gonna work, but I'll update when i get it.