I'm looking for a replacement crankshaft for my engine and I have located a new one, a used one and a repaired one. I'm trying to determine which I should buy. The new one would be nice but is about twice the cost of the repaired crank with the serviceable used crank being about half way in between. The repaired crank is available from the factory and they holding it for me but asked me to decide quickly.

A new crank wasn't planned and would blow my engine budget to the point that I likely wouldn't get it put together this year. Obviously the price of the repaired crank is enticing but I don't want to regret being cheap.

I wouldn't hesitate to use a repaired crank, but then again I am cheap. It would be interesting to know the nature of the repair, although coming from the factory I would feel fine with just about anything seeing is they are willing to put their stamp of approval on it. Most likely it was something minor in the first place.

As long as it has been inspected and the journals and pins ground to new limits, either of the not new cranks would be fine.

Look at the price of bearings for whatever size the crank has been ground to. I don't know about the IO-360 specifically, but some of the Continentals can have the crank ground down to -.020, but the price of bearings for 20 under cranks is quite a bit higher.

Personally, I'd go new or used...but that's just my opinion. Can't say I've ever had any bad experiences with repaired cranks in aircraft, but I can't say it'd give me a really warm fuzzy feeling about the time I was a long ways from a good landing spot.
JH

I've been leaning towards the used and yellow tagged crank for piece of mind but I didn't know if I was being overly sensitive. So far the only undersized bearings I've found are twice the cost of standard bearings. So with bearings the used crank is $400 more than the repaired crank with bearings...seems like a no brainer.

Well, a repaired crank from the factory (I assume your referring to Continental) will have a warranty. Used yellow tagged doesn't usually. Is the repaired to new limits? If so, I wouldn't be afraid of it.

MTV

Repaired is from Continental. Ground 0.010 under and no warranty.

I would go with the repaired crank. Look at it this way, if you had a crank core that was serviceable if turned .010 under, you would use it wouldn't you? The only down side is it could only be turned one more time before being non airworthy and has the potential to make a future overhaul more costly. Tens of thousands of auto and truck crankshafts have been turned .010 under for decades with what I believe is no loss in reliability. I also would consider a proven repaired crankshaft as safe if not safer than a new, unproven one.

Tim

did you check with dave at Wentworths or John at Colorado Airparts, Delta Colorado?

Colorado Airparts has/had the used crank. Didn't check Wentworth.

OK so I'm a little confused.

Is the used crank .010 under?
and the repaired crank .010 under also?


If so then the used was a repaired crank at a previous time.

If this is the case I would go for the continental ground one.

Yeah, it's about as clear as mud. Sorry about that.

The crankshaft from Colorado Airparts is yellow taged and at standard limits. John called it a zero zero crank. All it needed was polishing and now it is ready to go.

The crankshaft from Continental has been repaired, nature of the repair is unknown, and is ground 0.010. Also has yellow tag.

I realize "yellow tag" isn't proper terminology but I can't remember what the form number is. You get the idea.

whee wrote:Yeah, it's about as clear as mud. Sorry about that.

The crankshaft from Colorado Airparts is yellow taged and at standard limits. John called it a zero zero crank. All it needed was polishing and now it is ready to go.

The crankshaft from Continental has been repaired, nature of the repair is unknown, and is ground 0.010. Also has yellow tag.

I realize "yellow tag" isn't proper terminology but I can't remember what the form number is. You get the idea.

Another consideration is ....do they have new balance bushings/pins and weights installed?

Never ground could be better somewhere down the road at next overhaul.

POLISH ?

Pessimist: How much rust do they need to polish out?

Can they send you before pics.?

Sorry Whee - Just seen too many disappointed owners over the years.
Never me of course!

This is the BIG weenie in your engine.
I fully understand the desire to get it done, out of the way, and move on to the next.
Chris C

If the repaired crank is newly ground to 10 thou under I would go with that? Just polishing makes me nervous.

I'd go for the factory repaired offer. It's been checked for flaws using proven non-destructive testing methods, tested for straightness, and sized perfectly for undersized bearings. If this was a complete factory reman exchange engine it could very easily have a crank exactly like this installed, and it would have a warranty. Continental isn't exactly selling stuff out the back door that should have gone to the scrap yard. They're selling a used part that meets all their specifications and passes all tests.

Just in case you think I'm biased, I'll say that I don't like the culture at Continental, and not all of the parts they make are the best available, but I am a fan of how they run.

whee wrote:.........I realize "yellow tag" isn't proper terminology but I can't remember what the form number is. You get the idea.

Form 8130. I have one for a cylinder that's an 8130-3, there may be other dash numbers applicable to other parts.

What was the "repair"? If it was welding up a fracture, that's one thing, but if it was just turning down the journals to .010 under that's another.

As far as used, have you checked with Jerry Meyers Aviation (888-893-3301) in Bozeman?
He buys and sells used engine parts only-- no other used stuff. Might be more knowledgeable and have better stuff than Acme Aircraft Wrecker type operations.

hotrod180 wrote:

whee wrote:.........I realize "yellow tag" isn't proper terminology but I can't remember what the form number is. You get the idea.

Form 8130. I have one for a cylinder that's an 8130-3, there may be other dash numbers applicable to other parts.

What was the "repair"? If it was welding up a fracture, that's one thing, but if it was just turning down the journals to .010 under that's another.

As far as used, have you checked with Jerry Meyers Aviation (888-893-3301) in Bozeman?
He buys and sells used engine parts only-- no other used stuff. Might be more knowledgeable and have better stuff than Acme Aircraft Wrecker type operations.

I can attest to Jerry Meyers Aviation's reliability also.

I'm not sure I understand the trepidation about using a polished crank. Check the table of limits in the parts or overhaul manual. The transfer of very small amounts of bearing metal onto a journal is common. We're talking about a ten thousandths of an inch here. Or less. Polishing is common and meets manufacturers specifications. If one takes two measurements 90 degrees apart on any crankshaft journal one will likely find small out of round differences. The movement of metals due to heat expansion and contraction during running and after shutdown exceeds those numbers easily. The only way to get a "new" crankshaft is to buy a new crankshaft.

I'm not concerned about a polished crank. Polishing is part of the overhaul process at every shop I called. Two reasons why I'm leaning towards the crank from Coloardo Airparts: 1.Bearings are cheaper making the cost with bearings only $400 more than then repaired crank. 2.It is a "zero/zero" so it still has lots of room for a regrind if needed when overhaul time comes.

Both cranks come loaded with weights/pins/bushings applicable to my engine.

I'll give Jerry a call and see what he has. Would be nice to lay eyes on the part and make the deal in person.

I would suggest consulting with Bob Barrows. He knows more than most about engines, looks for cost effective solutions but doesn't cut corners on safety. I would follow his advice.