6.2/6.5 Cylinder Block Date Code

[More Power]

What month, day and year was this 6.5L block cast?

To answer the question... All of the 6.2L/6.5L cylinder block casting dates up through November 2001 used 4 digits. The reality is though, that GM stopped casting these cylinder blocks well before the November 2001 hand-off to AM General.

The beginning letter (A, B, C, etc) indicates the month; A=January, B=February, etc.; the "C" in this case tells us it was March. GM didn't use some of the letters of the alphabet in any casting codes because of a possible confusion with a number, such as the letter I or O. The next two digits in the above block code shown indicate the day of the month that this block was cast; in this case the "06" indicates the 6th day of the month. The fourth digit indicates the year in which the casting was made; in this case 199"6", because we know it's a pre-oil spray 6.5L block. So this 6.5L block was cast on March 6, 1996.

With just one digit indicating casting date year, you have put the block into context with what we know the 6.2L/6.5L production to get the right year.

Jim

[chickenhunterbob]

March 6, 1996

is my guess

[DmaxMaverick]

Must be a trick question, but that would be my guess, as well. Did we win the prize?

[More Power]

Good job! You win an official "attaboy".

What can you tell us about the following number?

[DmaxMaverick]

It verifies a 6.5L casting. After the 599, and before the 929 and 506, with no piston spray, and no heavier bore casting in the rear cylinders. Probably the "weakest" of the non-spray castings. A good choice for N/A economy use, as it a little lighter than other castings.

[chickenhunterbob]

I would probably have guessed 141 suffix was BETWEEN 929 and 506, but may well have been wrong, it wouldn't be the first time.

[JonyGurt]

Good job! You win an official "attaboy".

What can you tell us about the following number?

Hello.
The part number 10237141 for the GM 6.5-liter diesel engine cylinder block contains the following technical information:
The first two digits "10" indicates that the part is related to the engine block.
The next two digits "23" represents the model year of the engine, which is 1994.
The following two digits "71" are a code that refers to the engine application, in this case, a 6.5-liter diesel engine.
The final two digits "41" are a sequence number, which means it represents a unique identifier for the specific engine part.
Overall, the part number 10237141 provides information about the engine block's type, model year, engine application, and sequence number, making it easier to identify and replace the specific part in case of any issues or required maintenance.

[More Power]

Hello.
The part number 10237141 for the GM 6.5-liter diesel engine cylinder block contains the following technical information:
The first two digits "10" indicates that the part is related to the engine block.
The next two digits "23" represents the model year of the engine, which is 1994.
The following two digits "71" are a code that refers to the engine application, in this case, a 6.5-liter diesel engine.
The final two digits "41" are a sequence number, which means it represents a unique identifier for the specific engine part.
Overall, the part number 10237141 provides information about the engine block's type, model year, engine application, and sequence number, making it easier to identify and replace the specific part in case of any issues or required maintenance.

Thanks for the info, but:



The above image of a GM 6.5 cylinder block casting code doesn't have the "71". And, I always thought the casting date code had it's own number on the opposite side of the bellhousing flange - either a 4-digit (GM) or 5-digit (AMG).

Interesting stuff though... Jim

[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

[john8662]

'141 is a 96 block with the 3/8" cooling lines. Has the boss in the back of the block that is just like a Hummer/Gvan turbo engine, but nothing is drilled or tapped (yet).

Have one identical to it sitting wrapped up.

Just like a '599 or a '929, just another year, but with the '97+ capabilities as far as rear mounted turbo.

I'd wager a bet that this block was also used in Hummers that used the turbo starting in '96, but w/o the piston oil spray coolers.

J

[DmaxMaverick]

The casting numbers are just that, casting numbers. The castings overlapped, depending on application. GM didn't stop one casting, and start another. Newer castings were started and implemented, while previous castings were still in production. If this block was a van/HMMWV application, that's likely what happened. Older casting in a later model. The order of casting I was refering to was the actual full number. The 141 castings began before 1996, and other castings were made during that time.

[ronniejoe]

In my experience with casting design and manufacture, it is unlikely that multiple castings were made at the same time. Some new old stock might have been used after a new one was introduced to foundary production, however. When casting changes are made, the tooling gets modified making it very difficult to go back to the older configuration. On occasion, an insert in the tool can be used to allow multiple design configurations, but this is costly, lowers precision and opens the door to parts with the wrong features. Looking at these blocks, I can see no evidence of inserts being used.

[More Power]

This block was sitting in Peninsular's shop the day we were there. It was removed from a motorhome with more cylinder taper than I've seen in a 6.5. This was due (we were told) to a collapsed air filter, that allowed the engine to ingest dirt for quite some time. Like others I've seen with washed-out cyls, #6 & #8 were the worst, though all eight holes were trashed.

Jim

[sparky196969]

My van is a 1995 one ton was the block use in the van's somwhat better then the 6.5l in a P U truck? I will get the casting number later today when i pull out the #8 glow plug to see if there is water in the hole

[More Power]

Does this mean December 17, 2003?

No, the first two digits are the month, the next two digits are the day of the month, and the letter indicates the year in which it was cast. So, a "03 17 L" would be March 17, 2004.

H = 2001
J = 2002
K = 2003
L = 2004
M = 2005
N = 2006
P = 2007

Jim

[Robyn]

My 929 block that is soon ready for the DaHoooley is numbered "F154"
June 15 94 ??

Non squirt, Large outer bolt.


Missy

[More Power]

My 929 block that is soon ready for the DaHoooley is numbered "F154"
June 15 94 ??

Non squirt, Large outer bolt.


Missy

Yup... June 15, 1994.... Should be fine. If a well-seasoned block is crack-free now, it'll likely remain that way.

Jim

[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

[vongassit]

Hi, I have a J108 and a M238, both 506's and after a lot of searching i cant find any indication of a year. Anybody willing to shed some light on the subject. please