Confused about CUCV and CUCV II

[hwcurtice]

Walking a very thin line here:

A pre 86.5 GM/Chev is a CUCV while a post 86.5 is a CUCV II, correct? They don't seem to note the difference when looking them up.

My main question is, between a civilian rig and military rig, is there any real difference in the CUCV II (Post 86.5 GM)? It seems the engines in the pre 86.5 were different between civilian and military. Or am I completely off line here?

My main knowledge of the difference between diesel and gas is, diesel needs pressure to fire off while gas really doesn't. I can throw a match towards gas and it will flame off. I can throw a match at diesel and pretty much nothing will happen.

But it seems that the military required different specs for thier engines, even in civilian type trucks, like the GM pickups.

 

[Warthog]

The CUCV-II program started around 1996 and went thru 2000. They used the updated body style as compaired to the squarebody of the older trucks

Th LSSV (CUCV-III) started in 2001 thru 2007ish

Now to the engines.

The original 6.2L engine was produced from 1982 thru 1993ish. The Civvy and the Heavyduty (C and J code) are basically the same. The C code has some smog equipment and was installed in most lightduty trucks. The military and Heavy duty civvy trucks used the J code non-smog engines.

The 6.5L started around 1992 and for the first few years used mechanical DB2 injector pumps. I beleave it was 1994 when they went to the DB4 electronic injector pumps. The 6.5L was phased out when the Duramax came out in 2001.

 

[hwcurtice]

Is the 6.2 a modified 350 cid engine? I know the ones in the 70's were junk. I'm guessing they improved them somewhat in the 80's? And with no smog junk, it made for a better engine anyway?

I had an old Oldsmobile someone had converted the engine from diesel to gas. Seems they just swapped the heads and intake out. Starter was a heavy PITA. It went out on me and I changed it. I thought they swapped the entire engine out. Nope. Pulled all the muscles in my shoulder changing it.

But that's another story....

 

[Warthog]

The 6.2L is not a modified 350. It was a new design by Detroit Diesel.

The 6.2L was designed per GM requirements to be a fuel sipper, not a powerhouse. In stock form it does it job well

Many diesel websites have the true history of the engine.

350cubic inch converts to 5.7L

6.2L converts to 378c.i.
6.5L converts to 396c.i.

 

[Barrman]

The Olds 5.7 gas and diesel engines were not the same block. This is a website dedicated to the 5.7:http://a350diesel.tripod.com/story.html

They did use some of the same parts though. Such as the starter motor.

As pointed out above, the 6.2 was a total ground up diesel design. The IP on the 6.2 and 5.7 is made by the same company. Of course, so is the IP on the 6.9 and 7.3 Ford. They all look the same at casual glance.

 

[K9Vic]

It is also 1987 CUCV, not 1986.5. There is no such thing as a 1986.5, it is either model year 1986 or 1987 CUCV, there is no 1/2 year. The CUCV model years are 1984 to 1987 and the years of manufacture were Aug 1983 to as late as 1987, but I have only seen 1987 model years that were manufactured 1986.

GM did sell a 1988 K5 Blazer for the US Government, but it was NOT a CUCV and I do not know if there were any from 1989-1991. It was just a military spec 6.2L diesel Blazer with allot of the same likeness of the prior CUCV. I have seen one, but I do not recall if it has the 24v system or not.

 

[hwcurtice]

Well, they show it has a 1986. It doesn't look like the 1986 that we usually see has a m1008, or your 1984 m1009.

I know 1986 was the year they changed the design, halfway through the model year, and I've seen 1986 of the second half listed as 1986.

But that isn't the reason for the questions.

 

[K9Vic]

As I am trying to correct your error in model years, I answered your question and informed you that the CUCV model years were 1984 to 1987. I have personally owned 3 1987 CUCV pickups and there is nothing different from a 1987 to a 1984 CUCV M10x8 pickup or Blazers. They all have the same 6.2L Detroit diesel engine that was used in the civilian tucks & SUVs. My three 1987 CUCV trucks all had the same 6.2L as the multiple 1984, 1985 and 1986 CUCV trucks I have owned. Also my 1990 Suburban has the same 6.2L "J" code engine, but there are various emission parts that are not the same.

Below are my two past 1987 CUCV M10x8 pickups compared to a 1984 & 1986 M10x8 I also owned. There is noting different between them as there was no model year change in 1986.

 

[Barrman]

4 door trucks, Suburbans and full size Blazers didn't change in 1987 like the rest of the GM truck line did.

 

[K9Vic]

4 door trucks, Suburbans and full size Blazers didn't change in 1987 like the rest of the GM truck line did.

It is 1988 model year, not 1987.

 

[Warthog]

The 1987s old body style changed their letter designation from C/K to R/V in advance of the body style change. The new body used the C/K designation.

 

[Warthog]

Well, they show it has a 1986. It doesn't look like the 1986 that we usually see has a m1008, or your 1984 m1009.

I know 1986 was the year they changed the design, halfway through the model year, and I've seen 1986 of the second half listed as 1986.

But that isn't the reason for the questions.

If you believe everything GL says, I have a bridge to sell you....

The truck listed as a 1986 is really a 1988. Look at the VIN and the 10th digit is a J. J is a 1988.

It is just a plain truck that is painted green. No special upgrades except a 24v power converter for a radio.

I have one just like it.

 

[Barrman]

Sorry about the 1987 wrong ID. I was thinking fuel injection for gas engine change over which did happen in 1987 for Chevy

 

[hwcurtice]

Sorry about the 1987 wrong ID. I was thinking fuel injection for gas engine change over which did happen in 1987 for Chevy

Not a problem. I don't plan on beating you up over it.

 

[Tplane37]

This seems to be an appropriate thread to post this question in...

Did they have a crew cab CUCV? (84-87) If so, what was its designation ( M10?8 )? And were the Suburbans just civy suburbans with a new coat of paint and a 24v converter? Or were they the same heavy duty suspension as the M10x8 trucks?

I have an '86 civy crew cab C30 that had a military surplus 6.2L dropped in to replace the factory 6.2L J Code. THe only diference that I see is that the engine has an extra alternator bracket hanging on the driver side. But mine also has the bracket and linkage extension for the 700R4 (or TH350) hanging out on the intake, but has the TH400 behind the engine. For some reason, I actually like this old dog. It pulls our 5 horse steel Bison goosneck trailer easier than our friend's '99 Ford Super Duty... at least until we get to pulling up a hill or trying to get over 60 MPH! I think a turbo upgrade and swapping in the 700R4 will take care of that. But long and short, I am wanting another one just like it, but in four wheel drive, and I also wand to get a Suburban, but want the heavy duty 1.25 Ton suspension under it, and want the 6.2L in both of them as well.

 

[Warthog]

The military never had a crewcab or suburban in the original CUCV series. With that said they have always bought civvy units for every day use.

More that likely the drop in engine is from a HMMWV and the bracket was for the HMMWV transmission.

As far as the alternator bracket, as far as I know all 6.2L engines have the same mounting holes be it civvy or military. (ie. you cans brackets to either)

 

[Tplane37]

The military never had a crewcab or suburban in the original CUCV series. With that said they have always bought civvy units for every day use.

More that likely the drop in engine is from a HMMWV and the bracket was for the HMMWV transmission.

As far as the alternator bracket, as far as I know all 6.2L engines have the same mounting holes be it civvy or military. (ie. you cans brackets to either)

Is there a difference between the HMMWV trans and the 700R4? The guy I bought the truck from did the engine swap... and after further investigation of his mechanical abilities on this truck... Who knows where this truck really came from, but he did say it was from an "old military truck" and that he thought that the guy he bought the engine from got the engine from Memphis Surplus.

The other option is that the intake he had for the truck was put onto a long block, which would typically make sense for those trans brackets to be there, except when I ran the codes on the truck, it was shipped from the factory with the TH400 in it. So who knows really. I guess I could find another 6.2L truck and compare the intakes to see if mine is lower profile (e.g. from HMMWV)

 

[Warthog]

The HMMWV transmission is either a 3L80 (TH400) or a 4L80e. They did not have 700R4s.

as you said no telling where all the parts came from.

Check out LMCTruck.com to compare the pans on the different types of transmissions. The shape will tell you what you have.

 

[Crash_AF]

The J code was used in 3/4 and 1 ton civvie trucks, the military contract included cross swappable parts, so the K5 got the heavy engine and TH400. Also, the transfer case has the same gears in it as the 4.56 1 tons, but has a convertor box. Another bit of trivia is that the trucks are all based on the 1984 specs for the same reason, they did not get the model year updates for the rest of the run.

There were no Suburban or 4 door CUCVs, but the government did buy lots of them under contract, both with the 350 gas and 6.2 diesel engines.

The HMMWV had a single 24V alternator, so if there's a bracket for a second, it was a CUCV motor.

Later,
Joe

 

[MarcusOReallyus]

Another bit of trivia is that the trucks are all based on the 1984 specs for the same reason, they did not get the model year updates for the rest of the run.

That's a very important point, Joe. I think this is what confuses a lot of people. They look at changes in the civvy line for those years and try to apply that information to the CUCVs. Doesn't work. The military was not interested in being subjected to random model year upgrades like we see in the civilian world.

Remember these were intended to be COMBAT vehicles. They wanted consistency in order to simplify support. With everything the same, parts swap easily, manuals don't change, some poor slob trying to get a vehicle running in a tent in a combat area doesn't have to worry about what model year the vehicle is while he's trying to replace a starter or water pump or something.