Is it common for our oem crankshafts to crack? I am in the middle of getting an engine built and have had two cranks now go through inspections and a crack was found.


1st engine did have a bent rod so the crack in the crank was no a big surprise. But the 2nd crank came out of a good running engine with 104k miles, so I thought it would be fine, but it turns out that it has a crack as well.


At this point, is it worth it to purchase a used crank again and hope its not cracked or just purchase a brand new $850 oem crankshaft?

 

Manley, Eagle and few others have great choices for aftermarket cranks. you should look into that option and never look back!

 

I have only seen one 2.0L crank break...microfractures arent uncommon in 800+whp cars. Doesnt mean they will break though.

 

so are you telling me that a fractured crank is reused in 800 whp builds?

 

+1
You want to look at the direction of the crack across the journal vertical or horizontal
send it to english racing see if they'd use it

If yes forget about it

 

well my builder does not want to put a cracked crank in no matter what. He is pushing me to buy a new factory crank.

 

I suggest that you had third opinion.
Few are well educated to make correct judgment calls in terms of recognition and understanding of surface imperfections and actual meaning of the manifestation.

Cracked 4G63 crank is so rare, that most have never witnessed it, which is practical proof of their integrity, and proof that if one is found to be cracked one should get it verified by an entity with experience and reputation for the specific 4G63 application.

To me it sounds like very inexperienced people are using a test, and do not know what to make of it.

Remember this: you can do a job, half-***, for ever. Even if you have 15 years experience doing half-*** job, it does not make you good.
Doing a good job, is not too common because few people have the technical aptitude and desire and drive to learn through experience and education to really understand and know their profession truly well.
So even than, you can make a mistake, especially on judgment calls.

I think that both are "false positives": plenty of cranks have had rods bend...and none cracked.

My suggestion: go to another builder.
It seems that you are getting off on a wrong foot.

 

You can pick up cranks on Ebay for $250...pulled from junkyard cars with no known engine problems. He'll refund your money minus shipping if they have a crack. Just purchased one myself.

 

alpinaturbo - My builder is boostin performance. I would think they know what they are doing.

 

Before we consider using a used crankshaft, we always get them magnafluxed first before we spend time balancing and polishing them. Our machine shop has been doing 4G63 machining since the early 1990's and does all the machining for AMS's 4G63/4g64 and GTR engine packages too. The OP's crank showed a huge fracture around the #4 rod journal during magnafluxing. This crack goes 1/2 way around the journal and I can assure you its not a "False Positive". With this facture, I would never consider using his crank.


The second crank he had tested himself, so we never saw it.


BTW, fractures in Evo 4G63 cranks are not rare.

 

Manley Forged Crank for 600 bux is cheap insurance.

 

The Manley 88mm cranks suck for high powered cars!! I've seen a couple of them break and render motors useless (this was on 800 HP+ cars).

I've never seen a OEM 88mm crank fail, only test bad during magnafluxing. When it comes to a 88mm crank, the OEM version in my opinion is the best. Unless you can get your hands on a billet 88mm crank.

BP car's running OEM cranks
-Red Demon - 8.12 ET
-Junk Box - 8.77 ET
-Jason's Evo8 street car - 9.2 ET
-Kristin's Evo9 street car - 9.2 ET