thrown rod, less than 30 hrs on premium engine

[relayman]

I purchased a premium engine for my 1999 1200 SUV in
may of 2007. I have babied this motor, adult riden, putting only 30 hrs on it and now a thrown rod. Do i have a gripe or is this normal for SBT engines. The hardest thing we do with the SUV is pull a knee board now and then. Also I bought the block off kit and premix 50:1 religiously. The motor still cranks with a hole in the case so I know the fuel was good.

[John Kubiak]

Re: thrown rod, less than 30 hrs on premium engine

No that is not "normal" for any engine. there is usually some underlying cause for most failures. SBT produces a very good product, and I have installed dozens myself over several years. I have had to use their warranty service once out of all that I have installed.

As with all manufactured items, warranties have specific time limits. 2 years is a reasonable amount of time for a PWC engine, as most defects will show up within the first 30 minutes or so of operation.

I taught PWC repair for several years in my career, and was fortunate enough to tour the SBT facility on numerous occasions. The crankshaft department is top-notch, and they have several processes that are patented that improve the reliability of the OEM designs.

[Madfish]

Re: thrown rod, less than 30 hrs on premium engine

Your thrown rod may not be an engine failure, but something else that caused the failure. Something as simple as a dirty carb, condensation in gas due to the fuel we all buy which contains ethanol, or incorrect pop off pressure. These problems and others can cause a lean condition, where the piston and cylinder get extremely hot, seize, resulting in a thrown rod.

I'm not saying this is true with your motor, but I have read many stories where guys replace a blown engine, and the new engine blows up within a short period of time due to an external issue that was not diagnosed and corrected.

[relayman]

Re: thrown rod, less than 30 hrs on premium engine

The cyclinder was smooth and clean. The skirts were broken off the bottom of the front pison and the rod was broken as well. It appears that the rod bearing was loose and fell apart. This explains the "bell" ringing sound that we heard the last few times we cranked it.
I think that the rod bearing keeper was not tighten
properly at rebuild and it eventually flew apart throwing the rod, breaking the piston skirts and jamming the cylinder...

[relayman]

Re: thrown rod, less than 30 hrs on premium engine

Here are some more pics. Anyone have any ideas about what happened?