6.2/6.5 Cylinder Block Date Code

[Robyn]

Was fine, had one tiny crack starting in the number 3 outer bolt hole. Had not reached through the hole to the outside yet.

Inserted all 6 outers to be sure.

Bore .020 OS

Robyn

[scarmic]

Would realy appreciate some help clearing up a piont of confusion.

I have a block with the casting G 2 8 0 and assuming that this would be July 28 2000 if this is so is this block in the "The Danger Zone" as it is almost perfect ie no cracks and less than 0.00025" wear.

Anyway a merry Christmas to all on this forum and their loved ones and a healthy and prosperous new year.

regards Steve.

[More Power]

A 2000 year casting date is not out of the woods. We published a performance 6.5 story several years ago about a buildup using a 2000 block that had one small crack in a main web. This crack was repaired using the Loc-n-Stitch method, and has performed well since then - as far as I know - at least as late as a couple of years ago when I last communicated with the owner.

The block issues really didn't get sorted out till November 2001, when International began casting a somewhat redesigned block.

If yours is crack-free, be happy. If it was likely to crack, it would have long before now.

Jim

[Kennedy]

Was that Mark Bajus who did the Lock-n stitch?


FWIW I am getting calls from guys buying "Hummer takeout" engines. I've seen SOOOO much crap out there that I am really skeptical especially when the engine goes right into a truck heads and all...

[More Power]

Was that Mark Bajus who did the Lock-n stitch?


FWIW I am getting calls from guys buying "Hummer takeout" engines. I've seen SOOOO much crap out there that I am really skeptical especially when the engine goes right into a truck heads and all...

No, it was Andrew Ashwill's build for his 1995 Chevy. As I recall, Robyn is also experimenting with these crack repairs.

Jim

[OL 45]

Hi Guys & gals,
I have been reading with interest the info about age of blocks. The numbers on my old girl are: K137

From what I can gather the K indicates 2003. And I am thinking it is the 13th of 07 (July).

I have noticed some of the other block numbers are configured differently ie: 0137 L (permalink #14)

It doesn't take muck to confuse me as you can see.
Any help would be appreciated.

Cheers Greg

[More Power]

Your block date code indicates GM's earlier code sequence (pre-2001), so a K137 would equate to August (K) 13, 1997. I don't think the letter "I" is used in the sequence because of a possible confusion with the number one. Regardless, the last digit in the 4-digit code indicates the year.

Jim

[OL 45]

Your block date code indicates GM's earlier code sequence (pre-2001), so a K137 would equate to August (K) 13, 1997. I don't think the letter "I" is used in the sequence because of a possible confusion with the number one. Regardless, the last digit in the 4-digit code indicates the year.

Jim

Thanks for the info Jim, I got a little excited when I figured the block was a relatively new one. (wrong again). Am I right in thinking this year is in the range when there were some potential dramas with the cracks.

Are there any phisical indicators to tell if the block has oil squirters or do we know the blocks from years x to years y were fitted with oil squirters.

many thanks
greg

[Robyn]

All Blocks that were produced for the 97 production 6.5TD engines had squirters. (And later)

The early squirt blocks (97) were notorious for failures.
These blocks used 12mm outer bolts all the way through and they had larger diameter oil passages for the squirters than later ones.

The issues were, the normal cracks in the center main outer bolt
holes as well as a new twist. The main saddles would crack through the squirt holes and then proceed up into the lower part of the cylinders.

Once the crack hits the water jacket it was game over.

The 1997 506 Block (Good Wrench) that was in my DaHooooley did this very thing.

I would not touch one of these early 97 blocks on a bet.

For all the heart-ache I would either look for a good 599 or a 929 block or I would buy a new block from Cearwater cyl head and then move forward.

The 506 Blocks that were made by Navistar are supossed to be good ?????????

The new stuff by AMG/GEP are good iron but ya can't buy just a block.

The cost of a complete P4 or an optimiser is WAYYYYYYYYYYYYY to spendy $$$$$$$$$$$$$$$$

[Robyn]

Any replies to this post can be made on the 6.5 forum, lets keep this thread short and clean (MISSY)

Here is the real deal on the late 6.5 Block date codes

POST 2000

Starting in the 2001 year, GEP/AMG had taken over production of the 6.5 from GM

The date codes are a tad bit different 00 00 * letter code

The new codes start with H which is 2001 and the I is skipped due to its easy of confusion with the number 1

H=2001
J=2002
K=2003
L=2004 and on in the series

The first two digits are month
The second digits are the day
The last digit is the year

06 10 J would be June 10 2002

The late blocks also have the <> diamond in the valley towards the front

There is also a flat pad (drilled or not) for the rear turbo mount if used.
The LH side of the block has a slightly different machined pad configuration around the motor mount area.

All the bolt holes are metric as in the last few years of GM engines.

The casting numbers end with 506
The oil cooler ports are 5/8 pipe thread
The oil squirters and such are the same as the late GM blocks.


Also of interest

I scrounged up one of the 2002 GEP Blocks recently, this block is the same casting that is used in the Optimizer 6500

These blocks I am told by GEP folks were not supposed to be sold, but that some got loose from Navistar in 2002 and wound up in the general publics grasp

There is a very limited number of these blocks out there and the current attitude of GEP is that only complete long engines will be sold.
************************************************** *****
The other stories about the CAST IN CANADA blocks and such are all just BS according to the GEP rep.

These aftermarket blocks are all "CHINESE", cast and machined.

The testing that was done I am told on these blocks revealed that some of them have "CORE SHIFT" and some cylinders may be 3/8 thick on one side and 1/8th thick elsewhere.

Some seem fine they said, and others are just scrap iron.

If a chinese block can be ultrasound tested and if it has no appreciable core shift, they may well be fine, but without knowing this info, they could be a BOMB too

I also learned that GEP has in its hands a Direct injected 6.5 engine.
This was done using a standadyne pump and pencil injectors.
There were at one time (2) TWO OF THESE, one has since met its demise and the one test engine left is at the GEP plant being used as a test bed.

There is I am told an ongoing project to refit the P400 with a common rail direct inject head using piezo injectors.

How and when this will come to fruition, I do not know.

I was told that with the P400's strength that the direct inject setup will show some serious power increases.

The information I got, was that a optimizer 6500 can handle 225 HP easily.

With what More power accomplished with the "Power Project" its my feeling that the Navistar block equiped with a good crank (Scat or a forged one) could easily handle far more than 225 HP and live well.

Sooooo, if you stumble onto a Navistar block thats priced right, BUY IT

Missy

[DieselDobro]

I bought a Michigan K3500 Dually truck ($1200) in Nov/ 2011 that was Michigan rusted and rusted some more......BUT ...found out through digging into previous owners service records that the engine was replaced in 9/2003 at the Chevy dealer.

They spent 8k on just the engine. The truck has had 34k miles put on it since. Thinking AM/ GEP engine here.
I can't wait to see the date code when that badboy gets yanked out. I'm planning on dropping into a '01 3500HD dump truck.

Mark
'96 K2500, stock (so far) 98k miles
'01 3500HD 15k GVWR
'96 K3500 SRW
'97 K3500 DRW

[Robyn]

The AMG date code is XX-XX-Letter (H,J,K,L and so on)

(Example) 06-10-J)

H is the first year that AMG was in full control IIRC its 2000
I was not used as it looks like a 1
J is the next letter and so on
The letter indicates the year.

A GM installed engine in 2003 might well be an AMG built engine, BUTTTTTTTTTTT it might be an old stock GM engine too.

The date code layout will certainly show the story.

[Gunfreak25]

My 6.2 surplus engine has the common 14022660 casting. I know this falls under the "82-91" category but the engine also came with a permanently glued rebuild plate in the intake valley.

It is a Military rebuild tag from 2004 but it gives the engines serial number as "5HUM911" I am assuming HUM means HMMWV

On the left of the bellhousing flange there are no numbers or markings. However on the right there is a 3 or 4 digit code. I can post it tomorrow.

There has got to be documentation out there listing specific years for the common 660 blocks.

[Robyn]

The 141 block was another 6.5 block that came in there between the 599, that was the first edition (6.2 and 6.5 in the 92 to 94/5 vintage used the 599 casting)

The 141 came after the 599 and before the 506.

Rule of thumb. "If the mainline is not cracked, its a good one"

The early 506 blocks with the large (12mm) outer main bolts on the center mains AND the large diameter oil squirters were pretty sad sacks.

These were prone to main saddle cracking through the squirt holes and up into the cylinders.

The later 506 blocks have 10mm outer bolts on the center mains and the small squirters.

These were somewhat better but still no cigar.

The 97-99 506 blocks also suffered from Number 8 cylinder wall cracks up near the top, right below the deck.

Hummers had a big issue with these cracks (cyls)

Overall, if your 141 block has a good mainline without cracks, OR ones that are small and have had the Lock and stitch insert installed, your good to go.

Any time you have one of these engines down and all spiffy inside, one thing that really needs to be done is to remove all the stress risers in the bottom end.

OK to put this in basic terms, REMOVE all sharp edges on the main webs, lightly chamfer all bolt holes in the main line as well as lightly chamfer the oil squirt holes and the oil feed holes.

All of this stuff is razor sharp from the factory and can and does lead to the formation of cracks.

Like ripping a piece of paper, if the paper is folded SHARP is will rip easily.

The holes only need to be lightly chamfered.

Using a suitably sized counter sink, simply break the edge to about 1/64th inch wide, or even slightly less.

Its just getting rid of sharp edges thats needed.

The main webs are so sharp in these things (at the part line where the caps fit) that they will slice you up.

Break the edges at a 45 degree angle about 1/64th wide using a fine file.

Don't mess with the register fit where the cap fits in as this needs to be tight.

The chamfer on the main bolt holes can be a slightly more, maybe 1/32" wide.

The center outer holes are where MOST of the cracks occur and this is the reason for the chamfer.

Also, one can take a very tiny ball bur in the die grinder and make the sharp cut were the cap register fit is cut have a little radius at the base rather than the razor sharp right angle.

This is a simple job. Lay the bur in the base of the cut were you see the "L" and simply undercut the corner so its round instead of sharp.

The main register cuts can and do crack in the corner and then down the web. This is a GAME OVER situation as there is NO FIX for it.

In speaking with a castings engineer a while back, we discussed the incidence of cracked main webs on the 6.5 and his opinion, as has been mine for quite a while, that the cracks are the result of the castings being too GREEN (as in NOT cured)

A fresh uncured casting will move all over the place as it is subjected to hot and cold and "Duty Cycles"

When this happens and the casting is not stable, THEY CRACK.

THe design of the casting was poor anyway, given the stresses placed on them.

Look at the Dmax block and you can see what I mean.

The DMAX is buit with a cross bolted bottom end thats HELL FOR STOUT.

The 6.2/6.5 is just too flimsy.

Anyway, enough tech.
Your 141 if its in good shape can be a good chunk of iron to build on.

I have only seen a few of those, the 506 casting seems to be the most prevalent.


Missy

[Robyn]

As far as a LIST of what years used what casting numbers ?????

GM probably had documentation of such stuff, but I have never seen any definative listings.

There were definately overlaps in production runs of engines.

Depending on the total production of trucks and the production number of engines, the overlaps could vary.

The "660" 6.2 block was common for several years.

The last 6.2 engines were built on the 599 Block and were identical to the 6.5 except for the bore size.

The one piece rear main seal, crank and pretty much everything else was the same as the production 6.5

This change occured in the 91 model year in preparation for the introduction of the 6.5 in 92.

There were a lot of changes over the years that were phased into production.

One case in point was the mods to the oil pans. The GMT400 trucks (4x4) had to have a notched pan to allow fitting around the IFS gear box up front.

These same pans were used on engines that were installed in the V series trucks such as the Burbs, Blazers and the crew cabs of the "OLD SQUARE BODY" design.

Trying to figure out all the little nuances of numbers and such will drive you to drink.

Also after soo many years, the stuff has been swapped all over the place and into who knows what all sort of places that it never came originally.

The glued in tag may or may not have any real meaning.

I have seen a buttload of MIL engines and have not seen any tags on them.

I dont have any knowledge as to any practices of the MIL tagging rebuilts.

The stuff thats repaired in the field (combat theater) are usually running repairs.
If an engine has serious issues, they are swapped out with a fresh unit.
As far as I know the field shops do not do major repairs.

Robyn

[Gunfreak25]

Great write up Missy. In regards to the Army rebuild tag however, it specified a Camp Dodge, IOWA overhaul that included 030+ bore over, -010 on the rods and mains. The Serial of 5HUM911 on the tag is also stamped into the top drivers side edge along the intake valley on the block. Pulled the heads yesterday for some valve polishing (it's been sittin awhile) and confirmed the .75mm (030) oversized pistons. This thing is brand new inside, no cylinder ridges and the internals are still covered in gloss black enamel.

The tags are usually in the intake valley and are glued on with a REALLY stout glue. Took a lot to get mine off but it's going to be riveted to the dash instead so it doesn't get lost on the road.

[sctrailrider]

Great write up Missy. In regards to the Army rebuild tag however, it specified a Camp Dodge, IOWA overhaul that included 030+ bore over, -010 on the rods and mains. The Serial of 5HUM911 on the tag is also stamped into the top drivers side edge along the intake valley on the block. Pulled the heads yesterday for some valve polishing (it's been sittin awhile) and confirmed the .75mm (030) oversized pistons. This thing is brand new inside, no cylinder ridges and the internals are still covered in gloss black enamel.

The tags are usually in the intake valley and are glued on with a REALLY stout glue. Took a lot to get mine off but it's going to be riveted to the dash instead so it doesn't get lost on the road.

A lot of times, that tag & glue is a heat type glue, it is designed to turn loose and fall off if the motor gets too hot, one way the builder knows if it has been over heated....

[Gunfreak25]

Makes sense! Wow, I did not think of that!

[3ace]

As far as a LIST of what years used what casting numbers ?????

GM probably had documentation of such stuff, but I have never seen any definative listings.

There were definately overlaps in production runs of engines.

Depending on the total production of trucks and the production number of engines, the overlaps could vary.

The "660" 6.2 block was common for several years.

The last 6.2 engines were built on the 599 Block and were identical to the 6.5 except for the bore size.



The one piece rear main seal, crank and pretty much everything else was the same as the production 6.5

This change occured in the 91 model year in preparation for the introduction of the 6.5 in 92.

There were a lot of changes over the years that were phased into production.

One case in point was the mods to the oil pans. The GMT400 trucks (4x4) had to have a notched pan to allow fitting around the IFS gear box up front.

These same pans were used on engines that were installed in the V series trucks such as the Burbs, Blazers and the crew cabs of the "OLD SQUARE BODY" design.

Trying to figure out all the little nuances of numbers and such will drive you to drink.

Also after soo many years, the stuff has been swapped all over the place and into who knows what all sort of places that it never came originally.

The glued in tag may or may not have any real meaning.

I have seen a buttload of MIL engines and have not seen any tags on them.

I dont have any knowledge as to any practices of the MIL tagging rebuilts.

The stuff thats repaired in the field (combat theater) are usually running repairs.
If an engine has serious issues, they are swapped out with a fresh unit.
As far as I know the field shops do not do major repairs.

Robyn

Hi,
I just purchased a military pulled 6.2L to install in my 1991 Suburban V2500.
The Valley has 660. The date code on the right hand back top of the block is M031. Both heads have two different numbers on them. Both have 567, one has K141 and the other has D292.
Can anyone help decipher the block code of M031?
Are the 660 blocks susceptible to these mainline cracks you're mentioning?
Overall should I be worried this engine will not last for to many more miles?
I was told that it would have between 10-40K on it.
Thanks.
Merrill

[Robyn]

M031 December 3 of 1991 is most probable
The letters go from A being January through B C D E F and so on, I is not used as it looks like a 1 and ending with M being December.

03 being the third day and the 1 being 1991

Any and all 6.2 and 6.5 engines CAN have main line cracks.
Some casting series were far more prone to it though.

There is no way to predict if, when, which one or why.

The crack subject has been beaten about for years here and on other forums.

Metalurgy, stress risers that were not removed (Sharp edges) and on it goes.

The real late blocks made by AMG after they took over are far better.

The P400 6.5 is the gold standard. This engine has a complete built in girdle in the bottom end.

The older 6.2 engines did not see as much cracking, but it did happen.

Many of these engines will crack early in life and run a good long time without any issues, and the cracks are not discovered until the block is examined at rebuild.