RX-1 engine damage!

[Rupp-Nitro]

My 05 RX-1 with 3,000 miles went boom this last weekend.
Sled ran good for 40 miles than I think the piston rod went through
The lower case. Changed oil before and there were no metal shavings
In the oil. What could cause this? There is a hole at the bottom front
of the lower case , it tore out the starter. Any symptoms I should
have seen before hand? Can't seem to load a picture.
Thanks

 

[maim]

sounds like connecting rod bolts worked loose. have seen a few posted in here that did that.

 

[Rupp-Nitro]

"sounds like connecting rod bolts worked loose. have seen a few posted in here that did that."

Thanks, was there a year(s) more poblematic?

 

[Indy]

 

[misterbrutus03]

2003's I thought were only known for the connecting rod bolts coming loose, but could be wrong. Seen it happen on two 03 engines and did exactly as you describe. Also seen 03's with over 10,000 miles and no problems. Hit or miss. I guess Yamaha just got lazy torquing these super crucial bolts.

 

[maim]

i thought i read about a couple of 04 and a 05s as well. one post i did rear, he found one of the nuts for the connecting rod in the sump of the motor when he tore it down.

 

[erosled]

The rod bolts or nuts being loose isn't the cause of the failure, it's the result. Bearings wear and the rod end loses it's clamping force as well as starts rattling around resulting in finding loose rod bolts/nuts when the engine lets go. Typically the cause of the boom is a lack of oil pressure at some point in the engines life leading to excessive and premature rod bearing failure. If rod bolts were loose from the factory you wouldn't get thousands of miles or multiple seasons before a rod pokes out the cases.

 

[Rupp-Nitro]

quote: "The rod bolts or nuts being loose isn't the cause of the failure, it's the result. Bearings wear and the rod end loses it's clamping force as well as starts rattling around resulting in finding loose rod bolts/nuts when the engine lets go. Typically the cause of the boom is a lack of oil pressure at some point in the engines life leading to excessive and premature rod bearing failure."

If this is the case, I wonder if putting on a after market oil pressure gauge would be helpful???
I wonder also, if damage to the rod bearing can take place if people over fill the oil tank? If you
check your oil dip stick with the motor cold and not warmed up it is easy to add too much oil.

 

[Indy]

did you buy it used? I think someone may have sold you a burnt sled

 

[erosled]

Most people miss the oil pressure light coming on, so i dunno if a gauge reading zero would be easier to spot, but a gauge will show if oil pressure is getting worse over time. Certainly couldn't hurt.

 

[Rupp-Nitro]

Yes, I bought the sled used a year and a half ago but didn't get
a chance to drive it until last week. I'm sure now there was previous
damage done to the motor. I just wish there was a way of testing a
Motor in the future to see if it's bad because this one sure seemed fine.