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Discussion Starter #1
Aftyer going and picking up the used 6.5 that i have been discussing,i called the dealer to try and find out exactly what i had.gave them the numbers off the motor and he didn't have a clue.Said he didn't have 6.5 listings with a W.All the W's he thought were 6.2.But, he really didn't know for sure.If someone knows and could tell me about YWL it would be great.Or some outer appearances that i should be able to tell the difference.I knew when i started this it was going to be a nightmare but not so soon.Thanks so much for any help you may have.
 

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look on the VIN. 8th digit is F or S for 6.5L.
 

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S engines get EGR and smaller precups - F gets larger precups.

Other than that they're the same, with '97 up getting oil-spray piston cooling.

More importantly, what is the casting number on bellhousing flange at rear of block?

OBD-I and OBD-II DS-4 system requires ECT in crossover and CPS in front cover - other than that, all engines are same.

If it's got no mains webbing cracks, all 6.5 parts interchange - stick it in the truck and go.
 

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Ok, I see you have just received the motor out of the truck. The 6.2L has a one piece rear main seal on the rear most main, visable when the flywheel is off. There should be a long cast number along the rear deck where the rear of the drivers side head would sit, a three digit cast behind the flywheel and possibly a raised bead number on the pump valley walls.
A 6.2L will have a bore smaller than 4" and a 6.5L is slightly larger, the difference between the two being ~.080"

Another visable difference in the two maybe the timing cover. a normally aspirated 6.5L or 6.2 will have no hole for the CPS or reluctor ring on the crank timing gear.

Also, a 6.5L turbo piston has the top ring 1/4" closer to the crown than a n/a engine
 

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Discussion Starter #5
Thanks guys for your info.Going out to see if i can put any of this together.Sadly i have no idea what the used engine came out of.It has the heads still on it so i can't see the pistons yet.The casting numbers on my original block are 506 and the used motor is 599.There are other numbers but i think they are the ones.Tell me if i'm wrong please.Wouldn't it be nice to be able to afford a new crate motor and not have to deal with the bull.Life just isn't that easy.
 

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A 599 can be a 6.2L or 6.5L and is the transition cast that can be bored to either displacement.
 

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Discussion Starter #7
Well i guess i can take that as one more feather in my hat.Options are always good to have.Can the 599 be bored .020 or so over the regular 6.5 bore?Would really like to know what the YWL is supposed to tell me.Thanks again,i'm sure there will be many more questions before this is over with.
 

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Basically what you're worrying over is this:

You've got two light bulbs maybe one 75watt, one 100 watt, or maybe both 100 watt

One is frosted, one is not - will the frosted one screw into the light socket the not-frosted one came out of?

Those letters make absolutely no difference, at this stage.

You got a 599 block - check it out -

if the bore is under 4", you got a 6.2

if the bore is over 4", you got a 6.5

the stroke is identical

if the bore is under 4", take your original 6.5 pistons - marked for cyl 1,2,3,4,5,6,7,8 - and the block to a machine shop, have the block bored to fit the 6.5 pistons.

use your original rods, pistons, rings, camshaft, lifters, pushrods, etc in the 599 block

use your heads on the 599 block

What will you have - a refreshed 6.5, with less wear on it than a gasser engine with 5000mi on it.

Why?

It burns Diesel Fuel - a light O-I-L - not gasoline.

Means the pistons, rings, cylinders, valves, etc do not wear like a gasser - they're constantly lubed, top-cylinder and bottom-cylinder.

Check your orig block - you'll notice the cylinders still have the original finish-hone pattern in every cylinder, almost as if new.

You can refresh the 599 block with your orig 506 parts, and come out with a very good running engine, for the price of a bore job and gaskets.

Only draw back is - overheating is what ruins Diesel rings, cylinders, pistons, bearings, etc.

How high and how often did the original engine overheat?

If never, you're good to go.

Now, this concept is gonna bring'em outta the woodwork like roaches, but believe you me - you can build this engine using all the original parts from both engines - the low-mileage 506 and the whatever mileage 599 - for the price of a bore-job and gaskets.

And , if done with care, it will last until the 599 block webs-out....................
 

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Discussion Starter #9
Man that was great.You told me everything i needed to know.Didn't want to tear down the used motor until i knew i could use it.Can get my money back if i need to.I saw something on the two blocks that were different.The 506 had a hole casted in the valley between the heads and the 599 doesn't.I will look into that and go from there.Thanks again that was very good infomation to learn.Just for the knowlege ,could i put everything externely from the 6.5 on that motor as it is and be ok? Maybe a different computer?I think i will need to put some thought into this.Thanks again.
 

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If the 599 is in running condition, the HB, timing cover and reluctor/crank timing gear from the 506 may have to be used to run the DS-4 IP, if the 599 doesn't have them (ie mechanical setup). The oil tap in the pump valley didn't happen 'till '96, before that the OPS sat at the rear of the driverside head on the block.

Another thing to check is the oil return for the turbo, if the 599 was n/a it will have a fuel pump where the oil return was.

Personally, I'd want to inspect the motor internals before installation. Rod bushings should be checked for slack, rod and main journals checked for wear and nothing like a fresh hone and a new set of rings regardless of how little wear on the cylinder walls. Compression rings shrink with use and the gap increases increasing blowby.
 

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The oil pressure switch was moved from the rear of the block to the valley when the Hummer and vans got the center-mounted turbo.

The rear-mounted site interfered with the drivers-side exhaust pipe, which routed up and over the bellhousing flange, behind the head.

Location is irrelevant to your use - the wire harness should reach

And, just use everything electrical from your truck, incl the Inj Pump, wiring harness and PCM
 

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Hello, i have a question about this statement by quantum mechanic:

"look on the VIN. 8th digit is F or S for 6.5L."

My van has a J for the 8th digit; it originally came with a 6.2 but had a 6.5 put in. I know this because i gave the casting numbers on the block to a dealer - the ones on the passenger side said D149, which, i was told, mean 04/14/99 was the casting date; and the casting numbers on the drivers side were looked up as well and they also confirmed this had a 6.5.
So then what does the J mean, and was the dealer who gave me this info wrong?
thanks,
Paul
 

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C is 6.2
J is 6.2
P is 6.5 Van/hummer
F is 6.5 truck no emmissions
S is 6.5 with egr
 

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Discussion Starter #14
It sounds like getting the 599 bored is my best route.The heads from the 506 were also cracked as the block was.Every pair of valves in both heads had a crack between them. I have been told that doesn't hurt anything and that people get them rebuilt anyway.Don't think i would like that very much.As far as i know it has never been hot.Hell i didn't get to drive the truck but about 10,000 mi. before it went down.In all of this,my original motor was also decribed as a HO.Would this also be automaticly dealt with in the process of changing parts over?

Grease fire if i'm not mistaken,the numbers casted on the block decribe it.The numbers and letters on top of the motor that have the s or f ect.decribe what G.M. did with that block.Is that right quantum?
 

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C is 6.2
J is 6.2
P is 6.5 Van/hummer
F is 6.5 truck no emmissions
S is 6.5 with egr
For hummers:
X = 6.2 (92-93)
Y = 6.5 na (94-98)
Z = 6.5 turbo (96-01)
F = 6.5 turbo (01-04) GEP
P = 6.6 turbo duramax
 

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Unfortunately, those multiple cracks indicate severely or multiply overheated engine, which would also be indicated by scuffing in one or more cylinders, particularly #8

If the pistons survived with little scuffing on the skirts, a set of rings will be needed.

Overheating is probably the major cause of the mains-webbing cracking out.

The problem is, most of the trucks on the road are second-owner, with no firm indication of what transpired with the orig owner, so failure is more difficult to pinpoint.

It seems to be the luck of the draw, in that case - you either get a good block, or you don't.


If that 599 block is clear, it will probably remain so, with a little care.
 

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Discussion Starter #17
In the end i have to look at it as i just paid $500.00 for a block that i still need to get machined.Are the good blocks so rare that it would justify that.I know finding a 6.5 block was not turning out very well.
 

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Thing to do, el-c, is remove the pan and inspect the block - you can also see the cylinders from the crankcase, the underside of the pistons, etc.

Will give you some idea as to which way to proceed.

If you decide to use the block, you will still want to go with new head gaskets, so pull a head to check bore size and head condition.
 

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Discussion Starter #19
I know now i need to make a decision.Might need to think about this.If i'm going down that far with it i might as well take it a little farther.I guess i should be paying attention to the posibility.
 

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Well, good luck with it - if you need any more input, give a post.

I'm interested in how it turns out.
 
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