Scored journal on an Arma Steel crankshaft

[capguncowboy]

I opened up a nice Rupp engine today. Great original shiny paint -- a super clean engine overall! But when I turned the crankshaft there was a clunk sound. I pulled the head and the piston wasn't moving at all so I opened it up the bottom. The con rod is busted. The cylinder bore is pretty beat up and the piston is toast. The journal on the crankshaft is scored too :surrender::surrender:

I know I can fix the bore by having it bored out .10 over (does anyone here do that?) and the piston/con rod isn't a big deal since I have more in a box of parts -- but that 2-7/8" arma steel crankshaft isn't easy to find, nor is it cheap.

Can the journal be repaired or is scrap?

 

[tecumseh power]

I've cleaned up a lot of cranks with just aluminum transfer, but looks to have grooved the crank, and if so it will need to be welded and reground. I think Delray knows of somebody that can do that, but I think he said it was like $100.

 

[OND]

Agreed Andrew...that crank looks pretty ruff ! Muriatic acid will take the aluminum off , but won't help the grooves.

 

[delray]

I think Delray knows of somebody that can do that, but I think he said it was like $100.

dang it, now i can't by that crank cheap.:doah:.......:laugh:
i would be more then happen to pm you a number and name if your interested in fixing it. or i will just send you $100 plus shipping and buy that junk motor from you....:devil2:

 

[lawn-boy biker]

Throw another rod on and run it as a beater until dies completely.

 

[delray]

Through another rod on and run it as a beater until dies completely.

i don't think he can put another rod in it and run it. you see the cylinder wall.........it is done...:doah:

 

[lawn-boy biker]

i don't think he can put another rod in it and run it. you see the cylinder wall.........it is done...

All the more reason...
Just run till she blows.
Clearly, it was running when the rod went to begin with.
Who knows, it may even last a while.
I've seen and ran worse.

 

[Havasu Dave]

Yep. It's a lawn mower engine, running a sloppy aluminum rod without a bearing, or an oil pump. Run it, or if you really do lose sleep, have your local machinist weld it, then turn it, and feel "very" proud about owning the most expensive lawn mower engine crankshaft ever.

Hey do those fancy OHH billet rods come with bearings?

Andy, to answer your question, yes, a lot of us go .010 and .020 over on aluminum bores. Some of us even do it successfully with hones, decent hones, not Autozone rental hones. I have it on good authority, a Sunen hone will do a great job on these to .020 with no ovaling in the bore. However, since you're paying your machinist a few hundred to fix that crank, might as well go the extra few bucks to have him bore to your replacement piston. :laugh: And if you don't own the Neway set, have him go ahead and do a 15-46 valve job.

You just need to decide if the current over-inflated black-HS-with-Rupp-sticker market will bear the cost of your machinist/tools to DIY. "Anything" is possible.

Best bet it to carry the crank down to your local machine shop. You also might give these guys a call: https://www.koehlerinjection.com/Balancing-Service-machine-shop-urbana-il.html

 

[capguncowboy]

That about sums it up for me. Thanks Dave! Delray, I sent you a PM