Block identification

[Aftermath]

Can someone tell me the year of this engine and if it was a good year or not? Thanks

12555506
C280

[DmaxMaverick]

https://www.thedieselpageforums.com/tdpforum/showthread.php?t=24325

[Aftermath]

So Im guessing March 28, 2000....is this a good block??

[DmaxMaverick]

Yep.
It's about as good as GM spray blocks get. It's among the last casting runs GM did. Crack-check protocol is the same as any other, though.

[Aftermath]

So a guy down the street has this longblock for sale. He said it run fine in a 95 dually, but was scavanged and removed after the trans went bad. He ended up with the engine, thought about doing a diesel conversion in his gasser, then gave up hope.

My question is what is it worth site unseen. He says it runs fine, but who knows. No pump, turbo, intake or accessories. Just longblock.

I realize it could be a total loser, but it is what it is.

Whats it worth on the gamble?

Thanks

[DmaxMaverick]

I can't tell you what it's worth, but I wouldn't fork over any serious cash without pulling the pan and getting a good look inside. Maybe a cherry. Maybe a lemon.

[Robyn]

Take a look in the Valley and see if it has the <> logo in the casting (This is the navistar diamond) A GOOD THING

Navistar was casting the late GM blocks and IIRC the later stuff for AMG.

AS MENTIONED no hard cash until you can see in the bottom end.

Or get it in Writing that if the mainline is cracked you get your $$$$ back.

#2-3 main webs can and do crack by the outer bolts.

A crack is just not worth wasting time on these days.

I have inserted several old GM blocks and it will save most, but it's a pain...

Sadly the only real way to be sure the block is any good is to completely rip it apart...

Get the crank out and wash the block free of oil and then look at things.


A 2000 block will be a Squirt block and you need to check the main saddles to be sure the oil squirt holes have not cracked the web....YES THESE CRACK TOO...

If you are careful and keep all the bearings in STRICT order you can (If she is good) put things back and go again.

You can toss a lot of $$$ at a 6.5 with unknown history and wind up with zilch

Another thing to check is the #8 cylinder near the rear top outer edge and look for strange stains and a crack (close to the outer head bolt)

Also check the deck surfaces around cyl #1 and 2 (two fronts) for signs of erosion where the stainless fire ring sits (close to the dead end coolant passage)

If the deck has erosion that can be felt, then the decks need to be cut... ANOTHER BAD THING

WITH ALL THE MAYBEEEEES the value as a pig in a poke is no more than $200

All the BS talk about how great it is or such means nothing when it comes to a 6.5

Only a visual will tell the story...


Good luck

[Aftermath]

So I just bought another complete engine with date codes J126 So I'm assuming October 12th, 1996 ?? Or 2006? And if it's 1996 is it a good block? It has a GM GoodWrench sticker on the Driver's valve cover, was in a 1993 dually. So I'm guessing that at some point it was a new crate motor.

Any ideas of what it is??

Thanks in advance

[Aftermath]

Bump Bump Bump

[trbankii]

What is the other number?

https://www.thedieselpageforums.com/tdpforum/showthread.php?t=24325

[Aftermath]

what is the other number?

https://www.thedieselpageforums.com/tdpforum/showthread.php?t=24325

12555506

[More Power]

So I just bought another complete engine with date codes J126 So I'm assuming October 12th, 1996 ?? Or 2006? And if it's 1996 is it a good block? It has a GM GoodWrench sticker on the Driver's valve cover, was in a 1993 dually. So I'm guessing that at some point it was a new crate motor.

Any ideas of what it is??

Thanks in advance

The 5-digit date codes began in 2001, so... your 4-digit code has to be 1996.

There was a period of time in the late 1996 casting production dates that created a near catastrophe for GM's 6.5 program. They modified the early 1996 cast blocks to accept piston oil spray nozzles without considering how that might weaken those blocks. They cracked in droves.

[trbankii]

So I just bought another complete engine with date codes J126 So I'm assuming October 12th, 1996 ?? Or 2006? And if it's 1996 is it a good block? It has a GM GoodWrench sticker on the Driver's valve cover, was in a 1993 dually. So I'm guessing that at some point it was a new crate motor.

Any ideas of what it is??

Thanks in advance


12555506

So a 506 block from September 12, 1996. The other thread will fill you in on details of what that gets you.

[Aftermath]

The 5-digit date codes began in 2001, so... your 4-digit code has to be 1996.

There was a period of time in the late 1996 casting production dates that created a near catastrophe for GM's 6.5 program. They modified the early 1996 cast blocks to accept piston oil spray nozzles without considering how that might weaken those blocks. They cracked in droves.

Where would they typically crack?

This engine come out of a 93 dually, and surprisingly clean. I'm guessing it was a factory dealer replacement in 96. it has a GM GoodWrench sticker on the Driver's valve cover.

I have it stripped down to block and heads. I need to pull the balancer and timing gear housing, then the pan and take a looksee.

I will report back what I find.

Thanks !!!

[ronniejoe]

The early piston oil spray blocks suffered cracks in two places. The bodies of the oil spray nozzles were quite large requiring large holes to be drilled in the main webs to accommodate them. This removal of material weakened the web and caused a crack initiation site. Cracks would grow out of these holes up into the cam bore allowing the center three mains to become unsupported. Crankshaft breakage often followed. They also cracked through the outer main bolt holes. There is an undercut in the main web from the rough boring process for the cylinders. Cracks form through the holes and grow into this undercut area.

Later blocks used smaller body oil spray nozzles with much smaller holes in the web. They also used smaller outer main bolts.

The only way to actually address this problem is to modify the block for splayed main caps. I have built a couple of early oil spray blocks with splayed mains and had no cracking issues. My engine, a later spray block (A200 date code) with splayed mains has over 300,000 hard miles with no cracks.

Block cracking in these engines is actually associated with the type of use. If they are used to do heavy towing or heavy hauling, they usually crack (if not modified). The warranty replacement engine that was installed in my Suburban at 65,000 miles in late June of 2000 was a D100 date code, a little newer than my current block. It was removed after 160,000 miles because of a burned #8 piston and I found main web cracks in the outer bolt holes. Engines that don't tow or haul heavy typically don't crack. I attribute this to flexing of the block from torque reaction. The splayed mains stiffen the bottom of the block to minimize flexing and relocate the stress from the outer bolts to the thicker pan rail and away from the undercut area on the web.

[ronniejoe]

This first picture is of the early oil spray nozzle:

http://www.schoolcraftpowertrain.com/Pictures_&_Data/IM002169.jpg

The second picture is of the later oil spray nozzle:

http://www.schoolcraftpowertrain.com/Pictures_&_Data/IM001127.JPG

Notice the larger diameter of the main body of the nozzle for the early design.

[Robyn]

Great pics Ron

I bought an unfinished AMG block a few years ago and that story was told here in depth.
The block needed the bores finished and the mainline opened up .002"

Even the AMG blocks are terribly rough in the bottom end.

I spent 2 days deburing and getting rid of all the sharp edges (Stress risers)

I chamfered all bolt holes to remove the sharp edges, plus I used a small ball end mill and radius'd the lower corners of the main cap register in the block.

All stress risers were removed from the lower edges of the cylinders as well.


Any place I found a sharp edge inside that block I removed it...
I modified a small stone for the die grinder and chamfer'd the squirt holes in the main saddles to be rid of the sharp edges

All main bolt cap mating surfaces had the holes lightly chamfer'd as well as all sharp edges.

Sharp edges are a killer and are the first place a crack will form.


"Dehorning" or deburing is always proper machine shop practice, but even so may not stop all cracks...



..

[ronniejoe]

Actually, external corners don't really affect stress or cause stress risers. The reason that all my engineering drawings that I create have a note, "BREAK SHARP CORNERS .005 - .020 UOS" is to eliminate opportunities to damage mating parts during assembly and to attempt to eliminate the blood sacrifice from the mechanic's hands that so often comes with working on machines, not for stress considerations.

If you look at the strain fields resulting from applied stresses, you will see that strain does not flow into external corners. This is done by using photoelastic studies of materials under strain using interferometry. This may also be seen analytically through finite element analysis.

The problem arises when one has sharp internal corners or fillets. these force the strain flow lines closely together to go around the obstruction in their path. That is why you typically want to have generous fillet radii, as large as can be accommodated, on highly stressed parts. If the stress is low, it isn't as big of a deal.

The image shown here is stress distribution output from a finite element model for a bevel gear that I ran back in June for a customer.

http://www.schoolcraftpowertrain.com/Pictures_&_Data/Root Stress Distribution.jpg

Notice the concentration of stress in the tooth root, but not along the external corner between the active face and side of the tooth. These stresses are the result of tooth bending from applied load. If the root radius were smaller, this concentration would be significantly worse.

The attempted fixes that GM applied to the oil spray nozzle bores and the outer bolt holes both reduced the size of the hole. The smaller hole radius actually increased the stress concentration factor. However, it also increased the amount of material available to carry the strain, so the stress in that area was reduced. There is a balancing act that has to be performed in cases like this when selecting a hole size.

Here are a couple of links:

https://www.engineersedge.com/material_science/stress_concentration_fundamentals_9902.htm

https://www.corrosionpedia.com/definition/1035/stress-concentration-factor-kt

While deburring external corners is a good idea, it really won't help prevent cracking.

[Robyn]

Thanks for sharing this info.

[ronniejoe]

I should also point out that the date code that we are talking about refers to when the casting was poured. Final machining occurs sometime after that followed by assembly. Sometimes, this can happen quickly. For instance, my warranty engine with date code D100 indicates that the casting was poured on April 10, 2000. I actually bought my 95 Suburban around that time (on 4/16/2000, I installed a new 4WD actuator on the front axle just days after I bought the truck). This casting was installed in my Suburban on June 23, 2000 in Bismarck, ND. So, it took just over 2 months to go from molten metal to a running engine in my Suburban.

On January 8, 2005 (just under five years of service), the #8 piston failed and I found main web cracks.

Didn't last very long at all.