The engine is in a tractor about 1000 hours on a rebuild the nuts came off a rod. He said it started making a noise and was shut down. The cap rod bolts and nuts were laying in the pan. Is this 100% because of what the mechanic forgot or something else?
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3306 cat engine failure
- Thread starter Old Doug
- Start date
OzDozer
Senior Member
Sounds very much like someone forgot to tighten the nuts. Were the bolts in one piece or fractured?
The bolts were just bent a little . He didnt try but thinks the nuts could go back on. It never happen on one that i have worked on but i have seen this happen before . One was a 350 chevy and the guys that put it together were pretty sure they didnt tighten that set of rod nuts.
kshansen
Senior Member
- Joined
- Mar 11, 2012
- Messages
- 11,169
- Location
- Central New York, USA
- Occupation
- Retired Mechanic in Stone Quarry
Hard to believe a properly torqued rod nut would come off. Never came across that in all the years I was working on motors at the shop.
Had it happen on a JD 619 in my dads 8630 tractor about 40 years ago. Connecting rod capscrews backed off. We caught it before it let go. It had about 5000hrs from the factory. Apparently there was a campaign to replace rod bolts in some JD engines in certain machines. Apparently it didn’t get done. Also he had a 4430 tractor that kicked a rod through the block. Same problem. Update wasn’t done. Our dealer never admitted it. Dad had to cover the whole cost. I only found out about the rod capscrew update from a JD mechanic years later
That’s why i mark all critical fasteners with a white paint marker as soon as i torque them. If rod bolts are NOT to be re-used(stretch bolts), i use an old pair to do the plastigage check and then the new ones for final assembly
That’s why i mark all critical fasteners with a white paint marker as soon as i torque them. If rod bolts are NOT to be re-used(stretch bolts), i use an old pair to do the plastigage check and then the new ones for final assembly