Is my crank junk?
Thread Starter
Teching In
Joined: Jan 2009
Posts: 13
Likes: 0
Is my crank junk? I bought an LS3 (2009 G8 GXP) from a junkyard. Apparently it has less than 1000 miles. The front cover has a crack, it looks like it made contact with the crank pulley.
When I flipped the engine over and rotated the flywheel, the crank pulley is definitely bent. I removed the oil pan to check on the bottom end. I saw some marks on the crank lobes that looked suspicious so I took some pictures. The crank is in the same position in all pictures
1 - Here can see the bent crank pulley. The circled marks are what concern me.
2 - Here, zoomed out, more marks on other lobes.
3 - This is the larges mark.
4 - Looking towards the crank pulley.
5 - Looking towards the flywheel.
What do you think?
I don't want to remove the rod bolts, but I don't know what else I can do to check if the crank is ok.
When I flipped the engine over and rotated the flywheel, the crank pulley is definitely bent. I removed the oil pan to check on the bottom end. I saw some marks on the crank lobes that looked suspicious so I took some pictures. The crank is in the same position in all pictures
1 - Here can see the bent crank pulley. The circled marks are what concern me.
2 - Here, zoomed out, more marks on other lobes.
3 - This is the larges mark.
4 - Looking towards the crank pulley.
5 - Looking towards the flywheel.
What do you think?
I don't want to remove the rod bolts, but I don't know what else I can do to check if the crank is ok.
If you have a dial indicator you can check the runout on the crank snout if it took a lick on the balancer that will tell you if it is bent. You can also check the end play in the crank again with the dial indicator and see if it is in spec. If there is no runout in the snout and the end play checks out I would run it. The marks on the crank look like machine marks, can you see any marks where the crank has made contact with anything in the block or windage tray?
TECH Apprentice
Joined: Oct 2007
Posts: 302
Likes: 20
Spend a bit of time now and a lot less later...take the crank out and run it by a shop with a wet mag. They can give it a complete crack check and also check for runout. Damned few defects can be found with the naked eye.
FormerVendor
Joined: Mar 2010
Posts: 335
Likes: 1
From: Fostoria, OHIO
^^^^^^^Pull it, get it on a straight bench, and maggie! May cost you a few bucks, but it will be worth the piece of mind!
*edit
The browning, looks like you are picking up heat somewhere, even if contact is minimal.
-Adam @ Callies
*edit
The browning, looks like you are picking up heat somewhere, even if contact is minimal.
-Adam @ Callies
Last edited by Callies Performance; Jan 4, 2011 at 08:41 AM. Reason: more info
Thread Starter
Teching In
Joined: Jan 2009
Posts: 13
Likes: 0
Thanks for the suggestions! I will measure runout and endplay later today.
I don't see any point of contact on the block or windage tray, but I will take a closer look. It's hard to see anything with the rods in the way.
I'm reluctant to pull the crank because I still have the option of returning the engine. I don't want to remove it and have to buy new fasteners for the bottom end.
The marks feel lower to the touch and line up nicely with the low point of the crank pullley. If the numbers don't look good after measuring, I think I'll just return the engine.
I don't see any point of contact on the block or windage tray, but I will take a closer look. It's hard to see anything with the rods in the way.
I'm reluctant to pull the crank because I still have the option of returning the engine. I don't want to remove it and have to buy new fasteners for the bottom end.
The marks feel lower to the touch and line up nicely with the low point of the crank pullley. If the numbers don't look good after measuring, I think I'll just return the engine.
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Crankshaft end play specs are 0.0015-0.0078 in so it is in spec. The snout runout .006 seems in line should be good to go. If you still need peace of mind you can pull it and have it magnafluxed as stated above.
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