Will a spun main bearing ruin block?

[gawaterfowler]

I have an opportunity to buy a full motor (in pieces) trans and transfer for crazy cheap but the motor was pulled because it has a spun main bearing. Are the 6.4 block able to be used or machined back to specs from a spun main bearing? I have not seen the motor in person yet just curious before I make the drive and spend the coin

 

[ncollins64]

Curious also. Do you know if the block has ever had studs in it? I know it's not relative but it'd be good to know for your build.

 

[gawaterfowler]

Nope it's an all factory motor out of a service truck of some kind. I would assume maintenance was neglected a bit

 

[Strokersace]

Also curious. We suspect ours has a spun bearing as well, but haven't tore into it yet to find out.

 

[gawaterfowler]

I'm hoping the block can be saved cause it would be an awesome donor for my build!

 

[6.4f350]

Depends on the damage. May be able to get by with a line bore, or it may be trashed. Would need to be looked at by a machine shop to know for sure.

 

[gawaterfowler]

Any idea at what point it would be trash?

 

[tbsimmons]

Depends on the size of main bearings you can get. If its out .005 and you can only get .003 over then its too much out.

 

[78f100]

Yes it can ruin the block, I had one at the shop the customer continued to drive it with a bad front cover. Coolant had been going into the oil for a while, it trashed the block, because it removed too much material from the main journals. Line honing can fix it sometime, I can't remember spec right now but there is very little that can be removed to straighten it and bearing sizes are limited.

 

[gawaterfowler]

Well long story short it's a full motor minus turbo and injectors full tranny and transfer case for about 1200 worth a shot I reckon

 

[6.4f350]

Well long story short it's a full motor minus turbo and injectors full tranny and transfer case for about 1200 worth a shot I reckon

I wouldn't rush into that deal. Assume worst case, the block is trash, the crank is trash, used rods and pistons are worthless to part out, and you're left with two heads and a trans that are in unknown condition. Best case, it still needs a full refresh - that means parts, machine shop time, and labor if you can't assemble it yourself. Sounds like a lot of headache for little potential of turning a profit or ending up with a complete engine for much cheaper than you could buy a good one for.

 

[gawaterfowler]

Well I'm not going to rebuild a factory motor. Long term is a 800-1000 hp but looking for a good donor block to build outside of truck instead of it being down for months and months. But that's a very good point I could end up with a bunch of parts I'll probably never be able to sell and get all the money back.

 

[78f100]

It should be worth that in parts

 

[6.4f350]

E

It should be worth that in parts

Best case it will be. That means this guy will go buy it, find out the block is trash, and then spend the next 6 months dealing with forum buyers just to get his money back.

The only way I'd be comfortable with buying it is if you have a buddy that's a machinist that can go with you, or if you're pretty handy with a bore gauge and can get ahold of allowed tolerances.

I had an opportunity to buy a whole 6.4 truck last year for $3,000 but passed. It was a cab and chassis, and the engine was out and tore down but every last bit was there. A piston came apart and the wrist pin ate the cylinder wall. I have a buddy that's a machinist that would have put a sleeve in for cheap, but I figured up that after my time putting it together, money spent, and time trying to sell it just wasn't worth it. Sometimes cheap junk is just that - junk.

 

[Dzchey21]

The block can usually be repaired with an oversize bearing.

The crank probably needs turned as well so then you will need and over/undersized bearing. All available tho so hopefully it didn't go too far.

 

[neverkickn]

Sometimes cheap junk is just that - junk.

I have come to that conclusion as well.

 

[Groomzybanshee]

The block can usually be repaired with an oversize bearing.

The crank probably needs turned as well so then you will need and over/undersized bearing. All available tho so hopefully it didn't go too far.

Who makes the over size bearing for the block?

 

[Dzchey21]

You can get them thru ford

 

[DZL JIM]

I have 2 motors with spun bearings, the blocks and cranks are shot. The machine shop told me it's cheaper to get another motor by the time they weld to the block and crank and machine everything.
The one motor was so wore out the flexplate wouldn't even engage the starter. When we pulled the trans, we could push the flexplate side to side about an inch. There's not an over-sized bearing in the world big enough to fix that.

 

[Dzchey21]

I have 2 motors with spun bearings, the blocks and cranks are shot. The machine shop told me it's cheaper to get another motor by the time they weld to the block and crank and machine everything.
The one motor was so wore out the flexplate wouldn't even engage the starter. When we pulled the trans, we could push the flexplate side to side about an inch. There's not an over-sized bearing in the world big enough to fix that.

Yeah I would say that's an extreme case. The engine I have just spun after the crank broke.