Blown Piston Help! 2007 260 SeaRay Sundancer

Shipfaced · May 26, 2009

350 Magnum? MPI Bravo? III MCM Sterndrive (300 hp - 224 kW)

cruising along at 31mph on calm waters, speed gradually decends to nothing. flip into nuetral, puff of white smoke and can hear the bilge pump unloading oil into the water. oil pressure at 0 and they tell me the piston was blown off.

deep breaths...

how could this have happened? Is there something we did or did not do to provoke this?

side note: 2 weeks ago i let my idiot friend pump my gas for me. yeah he put in diesel!!! the boat was flushed and filters changed, but could this have caused the blown piston?

thanks for any insight!

JustJason · May 26, 2009

Re: Blown Piston Help! 2007 260 SeaRay Sundancer

Diesel in a gas engine usually isn't a biggie, it's the other way around that melts motors quickly.

Sorry to hear about your losss there. But only a full dissasembly is going to tell you what happened.

haulnazz15 · May 26, 2009

Re: Blown Piston Help! 2007 260 SeaRay Sundancer

Seems like there would be a warrantee of some sort on the engine being that new of a boat?

Bondo · May 26, 2009

Re: Blown Piston Help! 2007 260 SeaRay Sundancer

But only a full dissasembly is going to tell you what happened.

Ayuh,.... Time for some Forensic Diagnosis.....

Without a Complete History there ain't much that can be done On-line...

HT32BSX115 · May 26, 2009

Re: Blown Piston Help! 2007 260 SeaRay Sundancer

Diesel in a gas engine usually isn't a biggie, it's the other way around that melts motors quickly.

Diesel in a gas engine won't do much in a car.....

But Diesel in a Marine gas engine (that is working hard like running along at 3000 rpm or more) can cause detonation and pop holes in pistons.

Same thing happens in an fairly low compression aircraft engine that is mis-fueled with Jet-A1 fuel (which is nearly the same as Diesel #2 and almost exactly the same as Diesel #1)

You weren't burning pure diesel or it wouldn't have run at all...

You were burning a mix of gasoline and diesel which SEVERELY lowered the octane rating of the fuel making it far more susceptible to detonation

http://www.sacskyranch.com/deton.htm

Regards,

Rick

twostroke87 · May 26, 2009

Re: Blown Piston Help! 2007 260 SeaRay Sundancer

I was on a long boat trip once, and one of the foreign crew members pumped diesel into the boat. It wasn't a big deal the captain realized what happened after they stalled we could all smell it.

What I do remember is the tech at the marina saying that diesel is thinner than gasoline, and can pass right by oil seals and rings, which long story short he said means that you could have too high of an oil level in the engine.

He told us to make sure to check the oil level before we leave, if its too high to pump it all out and replace it.

Turns out it was a little more than 2 qaurts over on each engine, we ended up having to change it.

TilliamWe · May 26, 2009

Re: Blown Piston Help! 2007 260 SeaRay Sundancer

Well, if what Rick points out is true, guess what? You voided your warranty! It would suck to be you right about now!

Shipfaced · May 26, 2009

Re: Blown Piston Help! 2007 260 SeaRay Sundancer

thanks for all the comments

we purchased the full coverage extended warranty a few months ago, leaving us releived. but we're still curious as to what would've caused this to happen...

friends dont let friends pump gas!

boatguya1 · May 26, 2009

Re: Blown Piston Help! 2007 260 SeaRay Sundancer

Shipfaced said:
thanks for all the comments

we purchased the full coverage extended warranty a few months ago, leaving us releived. but we're still curious as to what would've caused this to happen...

friends dont let friends pump gas!

Read the fine print on the warr. very closely and be carefull what you say.

James

HT32BSX115 · May 26, 2009

Re: Blown Piston Help! 2007 260 SeaRay Sundancer

What I do remember is the tech at the marina saying that diesel is thinner than gasoline,

It's amazing how many "techs" do not know what they're talking about when it comes to petroleum based fuels.......They just make it up as they go......

TilliamWe · May 26, 2009

Re: Blown Piston Help! 2007 260 SeaRay Sundancer

boatguya1 said:
Read the fine print on the warr. very closely and be carefull what you say.

James

Oh yeah. You know he hasn't or he would be crying right now.

Blown Piston Help! 2007 260 SeaRay Sundancer

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