broken rocker arm on 425

[washita]

2007 425 with robin subaru engine 201 hours on the clock, rocker arm is split in to two pieces on the right cyclinder what happened?

 

[woodlandfarms]

Pictures if you can....

 

[BobRip]

Sorry for your loss. Can you give us more details. Does the engine still turn over by hand.
I will paraphrase from a mechanical engineer friend "The forces on the rocker arm exceeded the strength".

 

[washita]

still runs, not able to load on trailer though. pictures posted today if things go as planned. local go-kart dealer will warranty the motor (mechanic is not happy) concerned about hydraulicslooks like no go-kart he ever seen

 

[J_J]

I would say weak rod or defective.

 

[washita]

pictures: notice additional hairline crack at base of rocker arm, would this be a stamped part?

 

[Gravy]

still runs, not able to load on trailer though. pictures posted today if things go as planned. local go-kart dealer will warranty the motor (mechanic is not happy) concerned about hydraulicslooks like no go-kart he ever seen

Sorry about the problems...

But that there is FUNNY!

 

[washita]

here are pics

 

[Marks481]

Have you tried to push the valve stem in to make sure it moves? If the problem was only failure of the rocker arm, it only takes 5 minutes to replace it and adjust clearances.

Easier then trying to get the whole tractor to a mechanic.

I like the look of the old rocker arms on the Suburu's. About 6 years ago, they "improved" the design of the engine, and started using these stamped parts instead of the cast parts they used before. I think the original design was easier to adjust clearances; don't know why they changed.... except that I imagine the "improved" versions are cheaper to manufacture.

 

[washita]

good news new rocker arm is in, took rocker arm to college to today and had a hardness test performed on the broken rocker arm and the other rocker arm that was in the same head. The broken rocker arm was twice as hard as the unbroken rocker arm, the proffesor felt that it was to hard and therefore to brittle to handle the stress of the valve train in addition to a stamping flaw that was evident on both rocker arms. Hope this information will help other powertrac owners in times of motor issues and the alternating dropping of ignition was discovered to be a mouse chewed throught the grounding wire for the coils and the vibration would cause the wire to short out/ground the ignition coils at random