Question: AMG vs. GM 6.5's

[NDT]

Is there any reason to believe that current production AM General 6.5 L diesels are better, or more durable than those made by GM previously? Are the cranks still cast? I understand Navistar manufactures the raw engine castings for AM General. I would like to build a highly reliable 6.5 and was wondering which engine to start with.

 

[Crazyguyla]

As far as I know, they're the same engine. When I worked for GM, I replaced an engine in a H1 and it had the same part number as the military engine.

 

[jwaller]

the latest castings are indeed better. the old gm 6.5's had issues with #8 cylinder deck cracking.

you want the latest GEP block

 

[jwaller]

Main Bearing Web Crack: In both 6.2L and 6.5L engines this is reportedly fixed with a combination of improved higher nickel cast iron alloy and lower block re-design including, but not limited to, a main bearing girdle. These features are in the new for 2007 AM General GEP P400 6500 Optimizer enhanced 6.5L diesel presently being sold to the US Government for the 6 ton armored HMMWV.[1]
Crank Failure: Related to age failures of the harmonic balancer, the vibration damped accessory drive pulley, or the dual mass flywheel.
Pump Mounted Driver: Relates to thermal failures. The PMD is screwed to the DS-4 injection pump on the 1994-2001 GM 6.5 diesel utilizing fuel flow to dissipate heat. The injection pump is mounted in the intake valley (a high heat area). The PMD contains two power transistors that should be cooled by proper contact with the injection pump body. If the pump is not precisely machined to make complete contact with the transistors via the silicone thermal gasket and paste, the PMD is improperly installed without the gasket or paste, the PMD is installed off center with the pump body, or corrosion develops on the mounting surface the PMD will overheat. Several companies manufacture an extension harness and heat-sink kits. These allow an owner or their mechanic to relocate the PMD away from the injection pump to a lower heat environment and/or a place that can get more air flow.

 

[jwaller]

and lastly.
The Optimizer 6500: Engine Builder

basically you want a 1999 and later block. the 07's and up are the very best.

 

[Chief_919]

Yes.

The engines made by General Engine Products, the division of AM General that makes the engines, are better engineered and many of what were the weak points of the GM made engines .

The blocks used in them are cast by Navistar, and the weak points found in the GM blocks were engineered out. To verifiy you have a GEP/Navistar block, look on the block under the intake for the International/Navistar logo. I have seen GEP marked valve covers on old 6.2 blocks that people tried to pass off as GEP made engines.

 

[NDT]

Thanks guys, that was exactly the info I was looking for. jwallers link to the Engine Rebuilder's article said it all: The older GM blocks are considered scrap by engine rebuilding pros. That is why we see all the pull-out HMMWV engines coming out of DRMO and not going back for rebuild.

 

[Crazyguyla]

Yes.

The engines made by General Engine Products, the division of AM General that makes the engines, are better engineered and many of what were the weak points of the GM made engines .

The blocks used in them are cast by Navistar, and the weak points found in the GM blocks were engineered out. To verifiy you have a GEP/Navistar block, look on the block under the intake for the International/Navistar logo. I have seen GEP marked valve covers on old 6.2 blocks that people tried to pass off as GEP made engines.

GEP is the only company that rebuilds 6.2L as factory replacement engines, since GM stopped 6.2L production. That probably how the GEP valve covers got there. There has to be a source of 6.2L for older humves

 

[Chief_919]

GEP is the only company that rebuilds 6.2L as factory replacement engines, since GM stopped 6.2L production. That probably how the GEP valve covers got there. There has to be a source of 6.2L for older humves

All the rebuilds I have ever seen the military use were military rebuilt, not rebuilt by GEP.

The 6.2's that were going in older trucks were all rebuilds, however this year the Army declared that there would be no more 6.2 rebuilds and all older trucks would now get a slightly detuned 6.5 when a new engine is needed. When a unit orders a 6.5 they may get a brand new GEP one, they may get a rebuild.

 

[BugEyeBear]

GREAT ARTICLE!!

Q: For the Pre-99 6.5L engines are there any that are more prone to failure than others?

Specifically, I have a '95 Hummer w a 6.5L non-turbo.
Would this NA engine have a better chance of surviving than a turbo equipped model?
Is there a mileage where the failure typically occurs?
Are there conditions that promote failure?
Are there any warning signs of impending failure?
What can be done to prolong engine life?

THANKS!

 

[bugwugger]

I own a 96 6.5TD suburban with 230,000 and still going. I have replaced lift pumps and PMD's.
Id prefer pre 95 for the mechanical injection. The 6.5 doesnt have a tuner u can buy either. You can only turn the pumps up on the mechanical for more power.
hope this helps.

 

[Crazyguyla]

GREAT ARTICLE!!

Q: For the Pre-99 6.5L engines are there any that are more prone to failure than others?

Specifically, I have a '95 Hummer w a 6.5L non-turbo.
Would this NA engine have a better chance of surviving than a turbo equipped model?
Is there a mileage where the failure typically occurs?
Are there conditions that promote failure?
Are there any warning signs of impending failure?
What can be done to prolong engine life?

THANKS!

I know the heads are differant between the NA and turbo 6.5. I don't know what the differance is. I just remeber replacing some heads and one has a diamond mark and the other one has a square (i think).


Marcus

 

[jwaller]

GEP is the only company that rebuilds 6.2L as factory replacement engines, since GM stopped 6.2L production. That probably how the GEP valve covers got there. There has to be a source of 6.2L for older humves

6.2's are not being rebuilt. thats why the NA 6.5 came about. the 6.5 NA is the replacement for the 6.2L. the 6.5NA has been detuned to match the 6.2 performance.

 

[Chief_919]

6.2's are not being rebuilt. thats why the NA 6.5 came about. the 6.5 NA is the replacement for the 6.2L. the 6.5NA has been detuned to match the 6.2 performance.

Now they are not. Until last year there were some facilties rebuilding 6.2's

 

[Chief_919]

I know the heads are differant between the NA and turbo 6.5. I don't know what the differance is. I just remeber replacing some heads and one has a diamond mark and the other one has a square (i think).


Marcus

The heads are different on a 6.5 with the center mount turbo, but a 6.5 turbo from a truck application will have the same heads as the 6.5NA.

The angle of the mounting studs for the intake differ between the two.

The center mount turbo engines are much less common on the civilian side, being found in the vans only, and a few RV's. Civilian trucks with the 6.5 all got the side mount turbo. The HMMWVs equiped with a turbo get the center mount turbo, NA 6.5's for military use come with the same heads as the siide mount turbo trucks use.

I have a 2008 AMG/GEP NA engine transplated into my 94 Chevy pickup when the factory 6.5 blew.

 

[Stonepicker1]

I have a 2008 AMG/GEP NA engine transplated into my 94 Chevy pickup when the factory 6.5 blew.

Chief_919,
Where did you get your engine from (Franklin, OH ???) and is it the Optimizer 6500 P400 ?

I need one for my 1999 CUCV-II pickup that I bought from GL out of Tampa.
I thought I had a deal on two New 6.5 out of Chicago, but after driving 1600 miles it turned out they were rebuilt( one was a 6.2 )lol.

I plan on keeping the truck so I want the best 6.5 engine I can get. Thanks

 

[Stonepicker1]

Anyone have any info on the best place to get a Optimizer 6500 P400 6.5l engine ?
I would like to get this transplant done before the GA Rally
Question on Compression Ratio- 20.2:1 or lower to 18:1

 

[Chief_919]

Chief_919,
Where did you get your engine from (Franklin, OH ???) and is it the Optimizer 6500 P400 ?

I need one for my 1999 CUCV-II pickup that I bought from GL out of Tampa.
I thought I had a deal on two New 6.5 out of Chicago, but after driving 1600 miles it turned out they were rebuilt( one was a 6.2 )lol.

I plan on keeping the truck so I want the best 6.5 engine I can get. Thanks

I got mine from an Ebay seller in GA. He was getting very low mileage take outs from the USMC logistics base at Albany, I am pretty sure they were warranty take-outs.

Mine had a bent valve from a glow plug breaking off in it, but otherwise was great- it was so new the paint had not even worn off the pulleys and the manifolds were not even rusted. I pulled the head, put a new valve in, and had a 100% engine- and I sold the HMMWV manifolds, acessories, and injection pump and ended up getting a lot fo my money back.

 

[Stonepicker1]

Thanks Chief_919.

I thought you might of bought a new engine. I'm done trying to fine a used relacement and will buy new. Guest I'll call GEP and see if they sell to public.

 

[bugwugger]

CHECK THIS OUT!!! THE DUECE VS THE 6.5 TURBO DIESEL. I COULDNT CATCH UP. IM THE ONE DRIVING IN THE 6.5

8.22.2010 Deuce and a Half test drive videos