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Discussion Starter #1
Hi, im helping my friend replace the main bearings in his 6.2 diesel -1987. Its more or less a complete overhaul because he is gonna use it in his 79 C10.

We measured the crank yesterday with a micrometer.
Measurements and the bearings that were in the engine from the first main bearing to the fifth listed below.

Crank: Upper half of bearing: Lower half of bearing:
1: 74.933 0.013 US 786 0.013 US 786
2: 74.939 0.013 US 786 0.013 US 786
3: 74.927 0.013 US 486 0.013 US 886
4: 74.922 A200 882 A200 386
5: 74.929 0.013 US 386 A200 386

Is there anyone with the knowledge of which bearings we should use when we are doing the rebuild.

Thanks in advance.
 

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Measure the crank , then bolt the caps down with the bearings in and measure the id, you want .0025 - .0030 clearances. These are select fit bearings. If the crank is smooth you can use the same bearing sizes in the same locations.
 

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Actually those are all stock bearings. These engines are originally assembled with select fit bearings that is the same process with the 6.2 as it is with the 6.5 engines.

You did good documenting what bearing went in what position, that makes finding replacements and knowing where they go much easier. The block is stamped by each main cap what bearing size they determined was best for housing size, in your case .013mm in most of the case/block side. The bearings in the main caps are what the factory adjusted depending on what the crankshaft measured up at, so would vary based on the crankshaft. Again, yours is mostly .013mm, which is really close to standard (two halves of .013mm = .0005").

The bearings without a .013US on them are STD.

For replacement bearings, these were formerly only available from GM. Fortunately, we happen to now carry these. So if the crankshaft is in good shape with little to no scoring and a slight polish will work I'd just go back with the factory size bearings the block and crank were sized with. You can order these on our website here:

www.udgmtruck.com/mbsfkitns

There also a tech section for registered customers that covers the bearing thing in more detail.
 

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Yes your right about the .013mm bearings.They were indeed a factory size bearing during the manufacturing process.I’ve been inside a few 6.2 and 6.5 engines but I’ve only encountered std bearings so far.
 

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My understanding is also that you don't want to grind the crank in a 6.2 as they are surface hardened. Grind them and you lose that. I would get some plasti-gauge and check what you have. If they come out within spec, run em!
 
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What about blasting and coating the originals? Reinstall in same location.
Restore to factory tolerances?????
 

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Discussion Starter #9
Actually those are all stock bearings. These engines are originally assembled with select fit bearings that is the same process with the 6.2 as it is with the 6.5 engines.

You did good documenting what bearing went in what position, that makes finding replacements and knowing where they go much easier. The block is stamped by each main cap what bearing size they determined was best for housing size, in your case .013mm in most of the case/block side. The bearings in the main caps are what the factory adjusted depending on what the crankshaft measured up at, so would vary based on the crankshaft. Again, yours is mostly .013mm, which is really close to standard (two halves of .013mm = .0005").

The bearings without a .013US on them are STD.

For replacement bearings, these were formerly only available from GM. Fortunately, we happen to now carry these. So if the crankshaft is in good shape with little to no scoring and a slight polish will work I'd just go back with the factory size bearings the block and crank were sized with. You can order these on our website here:

www.udgmtruck.com/mbsfkitns

There also a tech section for registered customers that covers the bearing thing in more detail.
Hey and thanks for your respond.
Is it correct that we can use the same bearings as the ones that were in it when we took it apart, not the exact same ones but new ones with the same numbers?

Sincerely
 

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Yes, you can replace the bearings you have with the same replacement numbers and be back to factory. Hopefully the crankshaft shows little to no scoring. If so, a light polish at the machine shop will take care of that, but go by a machinist's inspection to be sure. The bearings will show wear before the crankshaft most cases, so replacement of the bearings in their same places will work just fine at restoring the clearances and crush the factory intended.
 

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Discussion Starter #11
Yes, you can replace the bearings you have with the same replacement numbers and be back to factory. Hopefully the crankshaft shows little to no scoring. If so, a light polish at the machine shop will take care of that, but go by a machinist's inspection to be sure. The bearings will show wear before the crankshaft most cases, so replacement of the bearings in their same places will work just fine at restoring the clearances and crush the factory intended.
thanks again for your respond.
can we order bearings even thou we are based in sweden?

sincerely
 
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