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Crankshaft installed correctly try and turn crank and it is locked up?

Tiny
HD1200
  • MEMBER
  • 2003 CHEVROLET SILVERADO
  • 5.3L
  • V8
  • 4WD
  • AUTOMATIC
  • 22,255,556 MILES
Rebuilding 5.3 vortec out of 2003 Chevy Silverado 1500

Installed crankshaft bearings and crankshaft checked clearance was in spec.

Installed caps and tightened to correct torque and angle to all bolts’

I know the numbers on crankshaft is correct for 5.3. I go to turn it and it’s locked up.

It was king main bearings I used?


It won’t spin at all. What could the problem be?


Thanks
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Friday, February 9th, 2024 AT 2:14 PM

20 Replies

Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,885 POSTS
Hi,

Will it turn if you loosen the main bearings one at a time, is there one that is loosened that will allow the crankshaft to turn? You lost clearance on one of them. Also, do you have Plastigauge available to you? If so, remove the caps and test each one. One of them is causing the problem.

I attached the torque sequence and torque below. Let me know if that is what was done. I don't think over-tightening would cause this. I suspect there isn't enough clearance at some point, but anything is possible.

Let me know.

Take care,

Joe

See pics below.
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Friday, February 9th, 2024 AT 4:28 PM
Tiny
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I used plasti gauge and it was in spec I’ll try removing one by one and check like you said thanks I’ll let know what I find.
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Saturday, February 10th, 2024 AT 3:28 AM
Tiny
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Just one more question, if I find one of the caps has lost clearance what’s the fix looser bearings or line boring. Could bearings be wrong? I’ve gotten mis boxed parts before.
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Saturday, February 10th, 2024 AT 3:52 AM
Tiny
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Updated: reinstalled caps and this is what I found. With all caps torqued and angle I can turn crank it 65-foot pounds with torque wrench. If I remove bolts from thrust bearing cap, I can rotate crank at 40-foot pounds of torque. I’m going to recheck clearance and maybe get a new set of bearings. How hard should crank be to turn I can’t turn it by hand at all.
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Saturday, February 10th, 2024 AT 6:09 AM
Tiny
JACOBANDNICKOLAS
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Hi,

Absolutely, the bearings could be mixed up and you have oversized bearings, but that should show up when you use Plastigauge. As far as how hard it should be to turn it, that matters what is actually installed. For example, if the connecting rods aren't connected, it should turn very easily, with little to no resistance. Make sure you lubricate the new bearings before installing them. They make a rebuild lube but I have always used something simple like STP oil additive.

Let me know. Also, it really shouldn't take 40 ft/lbs of torque to turn it. If you have the connecting rods connected and the heads on the engine, yes, it will be a lot more difficult because of compression, but I don't think that is where you are at this point. Let me know if I'm wrong.

Take care,

Joe
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Saturday, February 10th, 2024 AT 4:23 PM
Tiny
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It is just the bare block I’m going to measure all the bores with boar dial gauge and crank lobe that ought to tell more about clearance. I think I really need some undersized bearings.I should be able to tell once I measure It scientifically. It stayed the same when I removed the caps one by one. So, I think once I get measurements, I can figure out what undersized bearing I need.
I’ll keep you posted.

Thanks for the help.
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Saturday, February 10th, 2024 AT 6:12 PM
Tiny
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Update: I measured block bores with main bearings installed and torque and angle done on all bolts. I also measured crankshaft lobes. This is what I’ve found:

Crankshaft Block
1. 2.580. 2.565
2. 2.580. 2.565
3. 2.580. 2.565
5. 2.580. 2.565

Should I get 0.10 undersized bearings or.001 undersized or some other undersized bearings?

Thanks
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Tuesday, February 13th, 2024 AT 7:02 AM
Tiny
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For some reason the 5.3 crankshaft last 4 digits 2216 I put in first was too big I put another 5.3 crankshaft last 4 digits 2216 fits perfect I can spin with my hands just have to work clearance on this one. Thanks for your help.
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Tuesday, February 13th, 2024 AT 9:54 AM
Tiny
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Just wondering how can two of the same 5.3 crankshafts be so different.
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Tuesday, February 13th, 2024 AT 1:40 PM
Tiny
JACOBANDNICKOLAS
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Hi,

That is a really good question. It is possible someone sold you the crankshaft for a 5.7L. It sounds like it is turning normally now. That's a good thing. LOL

Let me know.

Joe
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Tuesday, February 13th, 2024 AT 2:52 PM
Tiny
HD1200
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So, 5.7 crankshaft has the last 4 digits 2216. The one I put in had the same number on crankshaft but was too big that’s why it didn’t spin the crank was bigger than the block bores. The one I put in I can spin with one hand, and it coast so I think I’m good.

Thanks, if you find out how two GM crankshaft with same Identification number can be different size.
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Tuesday, February 13th, 2024 AT 3:03 PM
Tiny
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Let me know.
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Tuesday, February 13th, 2024 AT 3:03 PM
Tiny
HD1200
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The machine shop balanced the crankshaft that didn’t fit and balanced the pistons and installed rods. If I take new crankshaft, to be balanced will he need the pistons back.
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Wednesday, February 14th, 2024 AT 12:16 AM
Tiny
JACOBANDNICKOLAS
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Hi,

They shouldn't need the pistons to balance a crankshaft. Did they provide you with the incorrect crankshaft?

Joe
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Wednesday, February 14th, 2024 AT 7:11 PM
Tiny
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No, it was mine both same Id number on them.
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Thursday, February 15th, 2024 AT 3:58 AM
Tiny
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Update, I got another block I believe the other block was warped at first, I put the main caps on from second block and still locked up. And cam was a little hard to turn. I put my balanced crankshaft in a new block checked with plasti gauge and is in spec and easily turns by hand I installed same camshaft and now it easily turns by hand. Have you ever run across an iron block warping?
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Saturday, March 2nd, 2024 AT 6:41 AM
Tiny
JACOBANDNICKOLAS
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Hi,

Wow, that was a nightmare. To answer your question, yes, it takes a lot of heat, but anything can warp. I can't imagine that it is a common issue. LOL

As far as the new one is concerned, it sounds like it is working as designed. I can only imagine how happy you are at this point. LOL

Regardless, let me know how things work out for you or if I can help in any way.

Take care and good job.

Joe
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Saturday, March 2nd, 2024 AT 11:23 AM
Tiny
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Yes, I’m excited I finally figured it out.
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Saturday, March 2nd, 2024 AT 11:34 AM
Tiny
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Thanks for your help.
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Saturday, March 2nd, 2024 AT 11:36 AM
Tiny
JACOBANDNICKOLAS
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Anytime. Feel free to come back in the future if you need help. We'll be here.

Take care,

Joe
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Saturday, March 2nd, 2024 AT 1:41 PM

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