Ultra 150 Engine Failure at 59 hours

[Indyxc]

Hello everyone,

I bought my 2001 Ultra 150 last summer (2005) with 27 hours still under factory warranty, as it was purchased new in 2004.

I have taken excellent care of it, ran KawaChem, clean/flushed after every run.

Ran relatively flawless up until the previous run at ~56 hours where it fouled the back plug. Had some unusual carbon build up with round carbon balls on the plug. Figured it was nothing, replaced the plug, ran normal again. That plug had fouled before, maybe twice, but no large build up like this time, just what looked like too much oil.

Make it out today, running fine, all the sudden zero power. Stop at the beach, and exhaust is in the engine compartment. Not good. It's very wavey, and no one else is out so I make it back to the harbor.

Take a quick look. Crankcase sharpnel laying the bottom of the hull, and exhaust coming out somewhere. I figured maybe it would lose compression at 150 hours, but a connecting rod through the crankcase at 59? Wtf. I should of bought the extended warranty. I've never heard of such serious problems at 59 hours.

I got home, pulled the spark plug arrestor and felt around the crankcase on the carb side. From feel there is a 1 inch by 1/2 inch slot in the crankcase on the back cylinder, the same cylinder that was fouling the plug. So my guess is something happened, the connecting rod snapped, and went through the crankcase.

Pulled the engine

Like I thought, the rear cylinder destroyed the crankcase. The crankcase cracked all the way around the bottom.

Oddly, the engine spins freely, and the rod is attached to the cylinder still, and looks perfectly straight through the hole in the crankcase.

From inspection it appears the short end of the connecting rod hit the side of the crankcase as there is a visible mark on the rod. HOWEVER, it appears like it has clearance right now, and the crankcase it cracked all the way around the bottom, in parts where the connecting rod doesn't look like it could reach the case.

I am completely confused at this point on what happened?

Not sure what the root cause of this is, and what to do with the engine now?

Thanks for the input.

[Indyxc]

Ultra 150 Engine Failure at 59 hours

Odd double posts.. please delete.

Thanks

[Technical Support]

Re: Ultra 150 Engine Failure at 59 hours

Most likely something has come apart inside or got ingested (you need to tear it completely down for inspection) and got wedged between the case and crank. You'll know more when you complete the tear down.

As for the repair, most likely you need a complete rebuild or new enigne, but you won't know until you fully inspect.

[Indyxc]

Re: Ultra 150 Engine Failure at 59 hours

Thanks for the advice.

I think you are right that something got wedged under there, because as is it looks the the rod has enough clearance with the case.

So I should tear it down and take a look inside? What are the potential parts that could come apart and wedge themselves in there? What should I look for?

I'll look in the hull, but I didn't see anything laying other than case sharpnel.

Thanks
Indyxc

[Technical Support]

Re: Ultra 150 Engine Failure at 59 hours

Everything must be in perfect shape to reuse it -you are inspecting the condition of the parts to know what you need to repair it, you aren't looking for shrapnel.

[Indyxc]

Re: Ultra 150 Engine Failure at 59 hours

Open the engine today finally.

Here is what I saw:

The top ring shredded into small balls, and stuck to the top of the cylinder head. I guess when the top ring was missing the piston could rock enough in the cylinder head, so at that point the bottom of the piston hit the cylinder, removing a piece of the piston.

Result was a missing chunk out of the piston that the rod most of put through the case.

So what is the root cause of this? The rear cylinder being starved for fuel? The carb back there not being tuned properly?

Whats the most economical way to fix this?

I'll post pics later.

Thanks

Indyxc

[RipperFox®]

Re: Ultra 150 Engine Failure at 59 hours

I would like to buy that broken case of yours.

[Indyxc]

Re: Ultra 150 Engine Failure at 59 hours

Digging this up after a year now, as I finally have the time and reason to put this back together.

I was thinking of buying the Standard SBT Engine. Can you give me an estimate idea on how much additional it would cost me, with the broken case as a core?

Thansk

[Technical Support]

Re: Ultra 150 Engine Failure at 59 hours

If those pictures show the full extent of the hole/crack, it's about a $300 welding fee.