stussman

Snapped a crank in half today during a bash session. Engine had aprox 30 lts fuel thru it. Had a new rod 10 lts ago and new bearings 20 lts ago. Rear bearing needed changing again but i hadnt bothered.
First major drama ive had with my os28s, ive had 3. Been great engines.
No biggie as i have cranks from the old os28s which i can use.
Is it unusual for cranks to snap in the middle?

Spetz

Pics please

stussman

There is a bad pic on my profile gallery.

theRCreverend

30L of fuel, that's pushing 8 gallons. If it was a flaw in the crank I would have expected it to break sooner than that, but that isn't always the case. I have owned hundreds of engines and only once had a crank break in the middle, and that was clearly due to a flaw from the factory. You say your rear bearing needed changing, maybe the play in that somehow precipitated the breakingof thecrank......increasedvibrations, etc.

stussman

A rock did jam in between the flywheel and chasis instantly stopping the engine a few minutes before it happened. Alot of stress on the crank when this happened. Probably weakened it further.