Differences between military and civilian 6.2L engines

[Towerguy1]

I need to replace the crank in my M1028A1 with the 6.2L engine. I wouldnt mind haveing a list if differences between military and civilian engines for referance in general. I know of a couple of civilian donor engines I can get parts from but obviously some of it wont be compatible. Any input would be good.

 

[mangus580]

Physical engine differences?

All Mil engines have the J-code intake, some civvy's had the c-code
Mil Engines have have a 'hardened' Injection Pump for running different fuels (different grades mostly)
Some of the temp switches, etc might be different.


Thats really it unless you start getting into accessories like starters and alternators.

 

[CUCVFAN]

I need to replace the crank in my M1028A1 with the 6.2L engine. I wouldnt mind haveing a list if differences between military and civilian engines for referance in general. I know of a couple of civilian donor engines I can get parts from but obviously some of it wont be compatible. Any input would be good.

As Magnus pointed out, the military used the "J" code engine in all CUCV's. This is the same engine that was used in heavy duty (non-emmmission) civilian trucks over 8600lbs GVW. The "C" engine was for light duty (emmissions) applications. I, too, have heard that the mil pump had some hardened internals, but I have also heard that it's just the same HD pump as found on the civvy "J" motor. Other engine internals should be the same. As was pointed out, the intake was different. The "J" intake flows a little better and the heads on "J" motors have different pre-cups in them. There may be a few other minor differences, but I can't remember off the top of my head.

If you get one of the surplus HMMWV engines, remember that all of its switches and sensors are 24-volt.

 

[Recovry4x4]

RE: Re: Differences between military and civilian 6.2L engin

Longblocks are the same. You have all the bolt ons so all should be good with whatever you find. Maybe a nice 6.5 will rear its ugly head!

 

[Towman2277]

RE: Re: Differences between military and civilian 6.2L engin

Yeah, a friend who works at Camp Shelby told me the internals ie. crank, rods, etc, are all the same on the two motors. You should be able to pick up a good at your local auto parts store, just make sure it's not ridiculously turned (.050/.050!!)

 

[dilvoy]

The rocker arms on the CUCV's are cast steel instead of stamped steel. but as far as my measurements went, they were the same ratio. I found this out when replacing a broken valve spring on a surplus truck with a 6.2 with a spring from a CUCV head. As far as the hardening of the injector pumps goes. In the humvee they are just like the civi units, Possibly somewhat hardened, except for the Arctic pump which is hardened and can be used with "thin" fuels, as well as living longer with low surphur diesel.

 

[85-m1028]

Re: RE: Re: Differences between military and civilian 6.2L e

Yeah, a friend who works at Camp Shelby told me the internals ie. crank, rods, etc, are all the same on the two motors. You should be able to pick up a good at your local auto parts store, just make sure it's not ridiculously turned (.050/.050!!)

My cucv is from camp Shelby!! mississippi right? what is with that place is it an active base or a training ground??

by the way I heard the military blocks had a higher nickel content than the civy blocks.

 

[CUCVFAN]

I think have heard this somewhere as well. But, given the fact that these trucks were built on the same assembly lines as civilian trucks, I tend to think that is probably not really the case. I could more readily believe it about HMMWV motors, since AMG would have ordered what they needed and it probably would have been a special run.

 

[rdixiemiller]

I believe AMG now owns the 6.2/6.5 engine plant and sells engines to GM.
Part of GM's restructuring plans to save money (read: try to keep from going bankrupt).

 

[Recovry4x4]

Robert, thats about right. GM made 100,000 warranty engines at Moraine assy before it shut down the line to convert ove to the Duramax production. AMG and GM have an agreeement for AMG to continue production on the 6.5 line and GM take over the name Hummer for the H2 and H3 lines.

 

[Towman2277]

85-m1028...... your right, it is Camp Shelby in Hattiesburg, Miss. Thats where I get alot of my parts for my truck- and it's mostly training grounds for Reserves, but they have alot of trucks and surplus flow through there for transport overseas. They bring tons of tanks, trucks, etc over to Mobile and load in the ports for departure, and a good friend of mine is one of the mechanics and maintenance techs.

 

[dilvoy]

I agree with CUCVFAN about the 6.2's all having the same metalurgy. They were not probleatic like the 6.5's were when they were highly loaded. When General Engine Products (GEP) the subsidiary of AMG took over production of the 6.5, they did change the metalurgy and casting design. I have been told that GEP never made any 6.2's and I believe it. I recently bought a surplus NOS 6.5 Humvee engine that was configured to be a drop in replacement for a 6.2 using a turbo 400. This engine has the top mount turbo boss at the rear end of the engine valley, relocated oil sender tap in the engine valley, new style timing cover with the place for the RPM sensor plugged and probably oil cooled pistons. However I have not confirmed the oil cooling part yet. I will pull the pan soon, but It makes economic sense for them to have used their 6.5 production engines and slap on the correct injector pump, for the replacement engines that they were building.

 

[swinters]

Different year civilian engines can have big differences. My 82 GMC 6.2 is completely different. Heads are different, threads for glow plugs, rods are lighter (and bend easier) and things like that. 84 and up are pretty much the same block. My 84 civilian suburban doesn't have holes drilled and tapped in some locations that my 84 M1008 does. Somewhere around here I have a spreadsheet from GM but will have to do some digging.

 

[southdave]

You are going to need this TM9 2815 237 34 it expains the difference from cucv to hmwv 6.5 to 6.2 ...

 

[wayne pick]

Different year civilian engines can have big differences. My 82 GMC 6.2 is completely different. Heads are different, threads for glow plugs, rods are lighter (and bend easier) and things like that. 84 and up are pretty much the same block.

This is true, and as you probably already know, your 82 GMC 6.2 is a "red block" engine, and was cast with a higher nickle content, as confermed at www.TheDieselPage.com. These engines were less prone to cracking and crank failure.

There is an interesting article at www.DieselPowerMag.com on building a high performance 6.2 "red block"

 

[forest522]

Glad this thread was resurrected! Very interestingopcorn:

 

[swinters]

This is true, and as you probably already know, your 82 GMC 6.2 is a "red block" engine, and was cast with a higher nickle content, as confermed at www.TheDieselPage.com. These engines were less prone to cracking and crank failure.

There is an interesting article at www.DieselPowerMag.com on building a high performance 6.2 "red block"

I have a couple of spares red blocks that I've kept since they're getting harder to find. Thanks for the link on the Diesel Power Magazine article - hadn't seen that one!

 

[wayne pick]

I have one that I found at a friends junkyard with 75K on a rebuild. I paid $500.00 for it complete with harness and not a bolt or nut missing. I guess I got a good deal. It's a C code though, but I took it anyway.

 

[swinters]

I'd have grabbed it too. If nothing else it'd give me a good excuse to expand the shop when I run out of storage room!

 

[wayne pick]

Yea swinters, you can never have enough storage space for spare parts, LOL. I pay $70.00 bucks a month for a storage unit for my stuff. The sad back story on this engine is the owner completely restored his 82 civi pickup and was heavilly rear ended by a tri axle dump on a exit ramp that was backed up getting off the interstate. he was Heart broken, and junked the truck. I was in the market fo a spare engine for my M1031 and checked out my lifelong friends junkyard. He said he had a 6.2 that has been "sitting up in back" for a few years. He had no idea about the red block thing, and thought it was just a 6.2, well when I saw the condition it was in I had to jump on it C code or not.

As per members of other websites that strictly deal with GM diesels, these red blocks are highly sought after by staunch 6.2 owners becuase they take to modifying better. Who knows? I may slap J code heads and intake on it, or just leave well enough alone and not mess with it. LOL!