6.2 diesel power

[JadXtreme]

My question is how reliable is the 6.2 naturally asperated diesel in the mid 80s trucks? What kind of fuel economy do they get? Is it a practical truck for everyday use? I'm looking at a couple of trucks locally that are for sale with this engine in it. Both are automatics with I'm assuming a TH400 tranny.

One is a red 83 3/4 ton reg cab long bed 4wd reading 45K on the odometer asking $600 obo. This truck is a little rough around the edges but a solid truck.

The other is a 85 Military spec 3/4 ton in full camo reading 65K asking $2900. This truck is in really good shape. Just no options because of the military spec.

[adamv7010]

are you sure the military truck is just a 3/4 ton? i had a military d30 series...but mine was on a 5/4 ton chassis..with the 6.2. very very solid truck...i gave 2500 for it with 56k on it. simple interior...one helluva drivetrain..

since im in NC also, if by some chance you dont get the 83, let me know..id like to see it...im wanting a 77-83 with a diesel.

[JadXtreme]

Originally Posted by adamv7010

are you sure the military truck is just a 3/4 ton? i had a military d30 series...but mine was on a 5/4 ton chassis..with the 6.2.

I say 3/4 ton, I saw one on ebay listed as a 3/4 ton and one listed as a 1 ton. So it may not be a 3/4 ton, but it is a military truck.

The military truck that I saw on ebay had a listed military top speed of just 55 mph. Is that just from the way that it was geared or do all the diesel trucks only go that fast from those years.

Just curious about the reliability and fuel economy of these trucks. I'm seriously considering getting one of em.

[killergmctruck88]

my uncle gave me his 83 chevy when i helped him move, It had the 6.2L motor, i used it for a few months before i sold it.. i got around 17mpg in city and it never gave me any problems in the few months i had it but it did only have 60k miles on it...

[=Lawrence=]

Are the 6.2 engines worth their weight? I never really hear about them, but diesels are pretty cool so I'm curious. Do they put out any decent numbers?

[killergmctruck88]

Originally Posted by =Lawrence=

Are the 6.2 engines worth their weight? I never really hear about them, but diesels are pretty cool so I'm curious. Do they put out any decent numbers?

not really, i think its around 155hp and over 300tq

[1988 GMC 355]

they are probably limited to 55 because of gears and trans.

but I would think either a gear swap or a OD tranny swap wouldnt be to bad and the MPG would go way up to.

[red suburban]

that military truck is a 5/4 ton, all that the military purchased (besides the navy who also bought a few duallys). 55mph top speed is because of the gearing and the trans, 4.56 gears and the stock 31" tires. they can go about 60-65mph but your getting close to redline. the 6.2L is not a big powerhouse by any means, but it wasnt designed to be. keep the engine temp below 210F and it should last for a long time. high teens-mid 20's for fuel economy depending on your setup. if you want extra power you can open up the exhaust and air intake. the J series motor (heavy duty) doesnt have the emissions crap in the intake manifold so flows the best, and the only headers (that i'm aware of) are on the humvee 6.2's, most free flowing but not a huge gain over the regular manifolds. can also turn up the injection pump some, rotate it till you get a puff of black smoke at wide open throttle, no need to go any higher. next power upgrade would be to bolt on the 6.5L turbo, intake and exhaust manifolds.

[Koots]

Originally Posted by red suburban

that military truck is a 5/4 ton, all that the military purchased (besides the navy who also bought a few duallys). 55mph top speed is because of the gearing and the trans, 4.56 gears and the stock 31" tires. they can go about 60-65mph but your getting close to redline. the 6.2L is not a big powerhouse by any means, but it wasnt designed to be. keep the engine temp below 210F and it should last for a long time. high teens-mid 20's for fuel economy depending on your setup. if you want extra power you can open up the exhaust and air intake. the J series motor (heavy duty) doesnt have the emissions crap in the intake manifold so flows the best, and the only headers (that i'm aware of) are on the humvee 6.2's, most free flowing but not a huge gain over the regular manifolds. can also turn up the injection pump some, rotate it till you get a puff of black smoke at wide open throttle, no need to go any higher. next power upgrade would be to bolt on the 6.5L turbo, intake and exhaust manifolds.

Just make sure you're engine is running healthy, run some cetane booster through it, adjust the fuel screw and the pump timing. It's not a powerhouse, but like any diesel it can tow without much effort.

My 83 K5 6.2L can pull my 98 Sierra around with barely touching the throttle around town (few bad pumps left it stranded). It's slow but feels exactly the same with a load behind it.

Basically, i liken it to a fuel efficient 305, slower but with more torque. It's got comparable numbers to the 305's of the time (even up until the vortec version came out).

I really liked the 6.2L, it kept me out of trouble, sounded fantastic at high RPM (in terms of diesel rev range) and was solid as a rock.

Just keep the coolant system healthy and full functioning, keep the intake clean and the engine inhaling and exhaling properly. Should be a nice workhorse motor that doesn't kill you at the pumps.

[JadXtreme]

I stopped and looked a little more closely at the 83 truck. It is a Scottsdale C10 6.2 diesel regular cab long bed. It is rough around the edges but seemingly a solid truck. It has duel exhaust and lockout front hubs. No radio and I believe no a/c. Roll down windows.

The truck needs a new windshield, though the current one would get by. Needs a new bench seat or the current rehopolstered(sp?). It needs a paint job. No dents that I can remember but some rust behind the rear tires. And some surface rust on the hood and top of the truck. The odometer list a little over 45K miles.

The owner is asking $600 obo for the truck and in the window it says that it runs good. Is this a good deal for the truck?

I'm probably gonna call the guy and test drive the truck tomorrow. One more question, what automatic transmissions did they put in these trucks?

[JadXtreme]

What gear might be in this truck also? I know the military ones came with the 4.56 gears but not sure about the regular models.

[Koots]

The truck could come with any number of gears, you'll have to write down the RPO codes to find out. It should be on a sticker in your glovebox.

My 83 has 3.42 gears with the eaton posi, but it could be lower or higher gears in it.

Personally, if the other truck is an actual M-1008 CUCV 1 ton truck. They come with the kinda axles people pay to swap over to lesser trucks, so you've got the best possible combo of axles for your truck up to 44" tires really. The K5 CUCV's came with basic 1/2 ton axles so it's nothing special.

It depends on what axles this truck you're speaking of has a good solid drivetrain. If it's got F60/R:14FF then you're good to go.

[GM Guy 1]

correct me if i am wrong, but the auto in the half ton would probably be the 700R4 the army truck probably has a turbo 400. Keep in mind that this is just a guess as to what it probably has, don't take it for the gospel.

I have been having a good time with my 6.2L, treat it well, and it will perform well.

[red suburban]

your right about the tranny options, 700r4 for the 1/2 ton and th400 for the military model.

[GM Guy 1]

If you really enjoy the simplicity of all mechanical, than i would recommend an NV4500 Swap, if you like the autos, I would look into getting a 4L80E from a 92-93 6.5L diesel, that would be the easiest upgrade, since it is from mechanical diesel to mechanical diesel. I think with some long legs, the 6.2L would return some excellent mileage.

[JadXtreme]

I went to go and talk to the owner of the 83 c-10 and he just sold it about an hour before I got there. Oh well. There will be more.

[crossy's son]

I've seen an 82 C10 6.2L that had a TH-400 in it. 3.08 rear.

According to all my books, from 82-87. TH-400, 700R4 were offered and you could get any gear. 3.42's were standard. 3.08's was the economy package and 3.73's or lower were optional.

What would be sweet is the C10 6.2L trucks came STANDARD with the rare 4spd overdrive NP833, rather than the SM465 which was optional.

But it appears the one your looking at is an auto, so either a 700r4 or or TH-400.