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View Full Version : Military 6.5, AMG/GEP engine-What year???


Rob4
03-01-2009, 08:40 AM
I recently acquired two ď6.2Ē military engines, both in the metal shipping canisters. The guy I bought them from guaranteed both to be good engines. The first engine was locked up and after I tore it down, I found that antifreeze had seeped into several cylinders. It didnít appear to have been run with the antifreeze in the oil but somehow it had leaked into the cylinders. In any case I will keep the engine as there are no block cracks and it could be bored out. Now, the second engine looks to be in very good shape. All lines and openings were capped. It has been run in a vehicle (Humvee???) but is fairly clean. When I asked for help in identifying the year of the block in the 6.2 forum, I was told that the 506 block casting made it a 6.5 block. I have measured the bore and it is indeed a 6.5 block. (Come on guys I didnít know the 506 was only a 6.5. I was told by the guy I bought it from it was a 6.2).
Now Iím trying to identify the year and find out if this is a good block to keep and use. It has the two triangles base to base in the engine valley. It has a valley oil plug and a valley drain tube. The three center main bearings have smaller outside bolts. A sticker on a valve cover states that it is from AMG/GEP. There are no markings on the block that says it is a GM block. The number on the driver side rear is 12555506. The date code on the passenger side rear is 09 12 J. The 0 might be a C or possibly a G. The J is slightly rocked to the side but sure looks to be a J??? See pictures. In looking through the previous discussions in the forum I could not find any discussions that showed a letter at the END of the date code for the year, just a letter at the beginning of the date code.
Also, I have pulled the pan and there donít appear to be any cracks. I can not find any squirt nozzles for the pistons. Can they be seen with the crank still in the engine? Is it possible for some Ď506í blocks to not have nozzles? Is the AMG/GEP block a better block over GM? When did AMG/GEP start making block design improvements and add the alloys to the block metal? Thanks in advance for any help you can provide.

Robert.

DmaxMaverick
03-01-2009, 05:39 PM
That appears to be a GEP block. The "triangles" you identified is the trademark of the Navistar foundry. There are some counterfeit Chinese castings with the markings, but not likely in your case (they've been marketed/sold as new, not used). Sounds like a nice block you got your hands on.

The piston spray nozzles may not be present if the engine was originally designated N/A. You may see casting marks, or plugs, where the spray tubes would be, if it had them. Or, you could have a casting that omitted the nozzle reliefs, completely. I've heard of them, but haven't seen one.

john8662
03-02-2009, 06:55 AM
The later (and I do mean later), mainly AMG production blocks, had a different date stamp than up to 2000.

This is why the block number ends in the letter.

Seriously, I'm looking for the block you've got, the 6.5, if you don't want it and would rather have a good 6.2, we can trade.

J

Robyn
03-02-2009, 07:25 AM
Early 6.5 blocks with 506 casting number had a 12mm outer main bolt on the center 3 mains.

If your block has a 10mm bolt on the outer holes of the 3 center mains then it should have squirts.

Now this said, the military stuff is all of its own. I have seen many MIL blocks that were a mixed bag when it comes to 6.2/6.5 and casting numbers, bolt sizes and other anomalies.

Check the main webs (center) for cracks in the outer holes.

These can at times be hard to see but even if you find some, as long as they dont go below the bottom of the hole and in to the web they can be fixed easily.

Best

RC

More Power
03-02-2009, 09:59 AM
This thread (http://www.thedieselpageforums.com/tdpforum/showthread.php?p=250914) explains the date codes for all 6.2/6.5 diesels. ;)

Jim

Rob4
03-02-2009, 06:57 PM
That would mean the block that I have was made in September12,2002. I still haven't found any piston squirts. Does this 2002 block have any improvements over the earlier 506 blocks made by GM or AMG/GEP? I heard at some point AMG/GEP beefed up the block and later added alloys to the metal. When did all this occur? Also this appears to be a NA engine. Are the NA engines the same as an engine with a turbo? If not, Any problems if I put a turbo on it? Thanks again.

Robyn
03-02-2009, 07:15 PM
Use a turbo, it wont care one little bit.
You can use a 4911 IP or turn yours up a little to get the power right

Keep EGT pre turbo at no more than 1100F and dont boost over 12 PSI

The little creature will do fine.

The N/A engines and turbo engines gets swapped all the time.

Best

RC

midniteplowboyy
03-02-2009, 09:44 PM
Your lucky about the N/A heads, IIRC the AMG HMMWV turbo engines still use the van style heads/intake.

More Power
03-02-2009, 10:49 PM
That would mean the block that I have was made in September12,2002. I still haven't found any piston squirts. Does this 2002 block have any improvements over the earlier 506 blocks made by GM or AMG/GEP? I heard at some point AMG/GEP beefed up the block and later added alloys to the metal. When did all this occur? Also this appears to be a NA engine. Are the NA engines the same as an engine with a turbo? If not, Any problems if I put a turbo on it? Thanks again.

The Navistar produced blocks went into AMG 6.5 production sometime November 2001. Till the P400 arrived in March 2008, those engines produced since 11/01 were the best 6.5s there were.

The NA 6.5 engines didn't have piston oil spray nozzles on the front cylinders - just the rear. You shouldn't have a problem running it with a turbo - within reason. Our Project 6.5 didn't have piston oil spray.

Jim

Rob4
03-03-2009, 05:15 PM
The Navistar produced blocks went into AMG 6.5 production sometime November 2001. Till the P400 arrived in March 2008, those engines produced since 11/01 were the best 6.5s there were.

When AMG started production of the 6.5 blocks did they have Navistar do anything different than what GM had been doing when the blocks were cast? What makes an AMG block better? From the gitgo did AMG make major improvements or did they follow a learning curve year to year? What changes did my Sept. 12 2002 block see? I've searched the forum but never really found an answer. It's probably been discussed but I havent found it.

Secondly, it was mentioned that there is a difference between a PU head and a Van head (perhaps as it relates to a turbo. Can somebody explain this? Thanks again for the help.

daustin
03-04-2009, 10:36 AM
Rob4,
I did almost the exact same thing you did, i got 2 ex military 6.5 engines, compete - fairly cheap. I decoded my 2 and came up with '05 and '06 for the block casting year. One i got had rust in 4 of the cylinders, looked like water got in it and it sat on one side. The other is nice and clean. I have the GEP AM General stickers on the valve covers as well. I looked for the oil squirters when i dissasembled one of them, don't see any at all. Both mine were N/A engines, aside from the one having bore crust they both appear really clean inside and crack free. Both 506 blocks as well. I'm going to get the good one set up for my '93 6.5 dually, hopefully get my local injection shop to convert the military 24V IP to 12V as it's dated '07, and should have the good head/rotor in it. Thanks for posting your info, good luck.
Don

More Power
03-04-2009, 10:51 AM
We've produced a couple of articles that discussed the AMG 6.5.

In an article produced by The Diesel Page in 2007, we said:


Once taking over 6.5L engine production in 2000, GEP initiated a bold engine program designed to end the cylinder block & head cracking problem that had nagged the GM manufactured 6.5L engines throughout the late 1990s. Solving the cracking problem involved a serious approach to both the design of the castings and to the metallurgical mix. To achieve the high level of expectations placed on these combat veteran diesels, design and casting duties were handed off to International Casting Corporation in Indiana - the foundry that produces the castings used in the Ford Powerstroke diesel. As a result, the grey iron used in the cylinder block saw the addition of molybdenum, which produced a 20-25% increase in tensile strength. In addition, the block design received taller and wider main bearing webs and caps, and the head bolt bosses in the block deck were strengthened, which improves cylinder head gasket durability. The cast-iron cylinder heads used in the 6.2L and the 6.5L diesels produced by GM could develop hairline cracks between the valves. AM General & International redesigned the head castings and added chromium to the cast-iron alloy. All of these design improvements add durability and greatly reduces the potential for cracking. As a result, the new AM General 6500 has become the best and most durable 6.5L diesel yet produced.


Jim