6.2 For A Daily Driver? What Are The Downsides?

[Originalthor]

Is the 6.5 the diesel in the CUCV's?

No but there in H1 hummers.

 

[Blue Ox]

Exactly! Iconic sound and history with 2smoke diesels!
On the bucket list to be the 6th or 9th build if the lord ever grants me the time to do things for ME….lol.
PS I’d do this 1000x over before wasting 15minutes on a 6.2 or 6.5 swap.
Whoever got paid to design the 6.5 and all its ridiculously quirky bullchit, especially in 94? or whenever they switched from mechanical injection should still be put on trial and convicted, no statute of limitations! Lol

How GM came up with that absolute mess that was the 6.5 T(ur)D is beyond me. It was like they bought a 1st gen Cummins, took it for a drive, felt the smooth power, opened the hood, looked at the utter simplicity of it and then said “That won’t do….” And sent it to the crusher.
Then got good n drunk, made some line diagrams with some made up parts that never existed before and never should have and after 100 iterations of random trial and error, found a combination of crap that actually ran long enough to get it off the assembly line and onto a delivery truck….

GM should have had its business license yanked by the govt for producing that ridiculous piece of _____! Lol.

6.2, 6.5 basically the same. More bore, some head redesign and later updates on the bottom end, but essentially the same engine.

To be fair to GM, despite their complicity, the electronic injection pumps were foisted on them by government emissions regs, and they did what they could with what they had. In fact, the first production drive-by-wire vehicle in the U.S. was a diesel pick-up truck. That's not a small feat.

Your mighty Cummins had to go electronic also, and those pumps had a high failure rate too.

 

[bucket]

GM didn't but....

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Oh my goodness... that is simply wonderful to see and hear.

Personally, I could drive an old Detroit day in and day out. The noises they make while in use are heavenly. Not a bunch of power... but the sound...

 

[Grit dog]

6.2, 6.5 basically the same. More bore, some head redesign and later updates on the bottom end, but essentially the same engine.

To be fair to GM, despite their complicity, the electronic injection pumps were foisted on them by government emissions regs, and they did what they could with what they had. In fact, the first production drive-by-wire vehicle in the U.S. was a diesel pick-up truck. That's not a small feat.

Your mighty Cummins had to go electronic also, and those pumps had a high failure rate too.

Totally agree. And part of it is me just talking sht.
I had a ‘94 (first year electronic?) 6.5 in the late 90s. Got it on the cheap with low miles. Truck was pristine condition except the bed sides was all scratched and dinged up and the PMD was shot and it didn’t run. $100 or whatever for a new remote mount PMD and repainted the bed and it was a good truck.
And at the time it was actually pretty powerful for a stock pickup. And I was blown away by a legit 19mpg out of a 3/4 ton 4x4.
But to be fair the VP 44 was a decent pump on the 24valves. More of them died due to lift pump failure than anything else.

 

[Grit dog]

Oh my goodness... that is simply wonderful to see and hear.

Personally, I could drive an old Detroit day in and day out. The noises they make while in use are heavenly. Not a bunch of power... but the sound...

Me too…as long as I got sponsored by Valvoline to keep them leaky sum beeches full of oil! Lol

 

[618Syndicate]

Oh my goodness... that is simply wonderful to see and hear.

Personally, I could drive an old Detroit day in and day out. The noises they make while in use are heavenly. Not a bunch of power... but the sound...

Back when I drove trucks for a living a concrete company I worked for had one in a dump truck. Every now and then I'd have to drive it, and they do sound great for like 20 minutes. But listening to one screaming up hills delivering rock with the windows down for a 12 hour work day makes that sound feel like needles are in your eardrums.

 

[Blue Ox]

Totally agree. And part of it is me just talking sht.
I had a ‘94 (first year electronic?) 6.5 in the late 90s. Got it on the cheap with low miles. Truck was pristine condition except the bed sides was all scratched and dinged up and the PMD was shot and it didn’t run. $100 or whatever for a new remote mount PMD and repainted the bed and it was a good truck.
And at the time it was actually pretty powerful for a stock pickup. And I was blown away by a legit 19mpg out of a 3/4 ton 4x4.
But to be fair the VP 44 was a decent pump on the 24valves. More of them died due to lift pump failure than anything else.

Not that GM nailed it with the 6.2L, but they were first to market with a light truck diesel that was intended to be a fuel-efficient alternative to a small block. Compared to the competition it had some significant advantages. Being a corporate engine, it was designed to be integrated into the entire product line, not just larger pickups. Ford and Chrysler buying engines from truck manufacturers, got truck engines. Big and heavy, that couldn't go in a Bronco or a Ramcharger. They only offered them in 3/4 ton and up pickup trucks.

You also have to take it in the context of the time in the fact that none of them were horsepower monsters. Both the 5.9 and 7.3L were in the mid 100 HP range at the time. It's a shame GM didn't make the main bulkheads of the 6.2/6.5 a little heavier. Not that it would have been capable of being a firebreather, but they would have had a little more headroom to work with.

GM - Always on the verge of doing something right - usually does its final phase of development with the customer. There were a fair number of issues with the electronic injection in the first couple of years. Most of them got sorted in a reasonable amount of time. Also, the PMD issue was never heat, although a lot of people made a good buck selling remote mounts. The only benefit to a remote mount is it makes it easier to change a PMD.

I'd still consider the VP44 an issue if it can be killed by a faulty lift pump. Especially since Jeezus Chrysler was supplying the lift pump. BTW, if you take one apart alongside a Stanadyne DS, they're mechanically almost identical. Biggest difference was Stanadyne used an optical sensor (as demanded by GM) and Bosch used a magnetic sensor. Surprisingly, the optical sensor was fairly reliable.

 

[Grit dog]

I thought heat was the issue with the PMD.
And totally agree, light duty diesels were in their infancy and GM lead the charge.
Can’t deny the massive fuel mileage gain and cheaper fuel ( back in the good ole days lol. Now the stations round here upcharge farm fuel to almost the same as road diesel when it should be about 60 cents cheaper and used to be until the last year maybe.)
I’ve seen plenty of high mile 6.2 and 6.5 on original internals. It’s all the added crap to the electronic injected 6.5s that I mostly don’t like.
Like the optical sensor and a some stuff that is oil pressure fired.

 

[Blue Ox]

I have no love for the electronic stuff either. And I don't have the time to type all the details on my phone, but the PMD problems were due to low voltage. Good luck convincing anybody of that though. The whole world swears it was heat.

 

[bucket]

Back when I drove trucks for a living a concrete company I worked for had one in a dump truck. Every now and then I'd have to drive it, and they do sound great for like 20 minutes. But listening to one screaming up hills delivering rock with the windows down for a 12 hour work day makes that sound feel like needles are in your eardrums.

Yeah, I'm different than most folks. Lol. I've spent some time driving an International with a 6-71... I'm in my happy place when driving that. If I could afford it, it would be my daily driver.

 

[alabummy]

I drive my 6.2 daily and have'nt had any issues with it as far as parts wearing out. It has the Banks glow plug conversion on it so they don't come on unless I turn them on. All the comments about sluggish are spot on, niot fast enough to get out of its own way but I'm never in a hurry to get anywhere anyway so its really a matter of what feels good to you. I love driving mine.


1985 K20
6.2

 

[Craig Nedrow]

I have a 85 6.2 that I bought a few years ago, and have been tinkering with it to no avail. New glow plug controller, rebuilt fuel injection pump, new block heater. Gets fuel to the injection pump, weeps out the fuel lines when I crack them open, but no start so waiting for warmer weather. Want to get it running and reliable, so I can tear down my 73K20 and finish the restore. A well optioned interior with the center wood cup holder, (cool man,) cruse, perfect no rust body. I have a 6.0 LQ4 with a 4l80e would make a sweet swap, but want to get the diesel running. I do not like working on Diesels...

 

[Thesiger]

I guess both your guys' vehicles are nicer, (Especially @alabummy, that rig is sweeeet) I'd be dealing with a rusty non-runner, Craig I guess I could really learn from what you've done, because I'll probably be dealing with the same problems as you. Have you messed with any of the wiring/wiring harness?

basically the only redeeming factor for the 1990 2500 6.2 'burb I'm looking at is that its SO cheap, (I could possibly get it for $1,000) but I don't want to be burdened with a money pit just because I can pick it up for a low up front price...

 

[Honest Bob]

Ive had a M1009 (blazer with a j code 6.2/th400/3.08 gears) for a couple years now.

Downsides:
Diesel is expensive
Loud
Slow (Its possible to accelerate on a hill on the highway but it really just dosent feel like it today.)
6.2 parts are expensive and sometimes hard to find.
Radiator? $400
Replacement oil cooler lines? Expensive and could only find them at hillbillywizard. GM used some proprietary connector.
Injection pump rebuild ($1000?) which is very high on the probability list of reasons why a 6.2 wont run right.
Vaccum pump - hard to find (the same vaccum pod was used on the 7.3 idi so I was able to use on of those).

Upsides:
18-20mpg


Common items you should replace:
crank pulley - the rubber disintegrates and can take out the whole motor when it goes
replace the stock box fuel filters with a spin on filter.
Remove the mechanical fuel pump and replace with an electric pump from a 6.5 (makes priming so much easier! keep a spare electronic pump in the truck)
Two good batteries - Do not try and start a 6.2 with weak batteries you'll just melt the starter solenoid contacts down. (hint a 6.2 starter aint cheap)
Fuel lines need to be checked, any tiny air leak will cause a diesel to stop running or not run.
Be prepared for an injection pump rebuild.
Glow plugs! Learn how to test them and replace the ones that arent working. If they all work you wont have issues starting it if your patient.

Why do the fuse blocks melt? Easy, loose electrical connections create heat. If you have a fuse thats kind of loose in the fuse box it will melt. You can tighten up the connectors by prying on them with a small screwdriver so that the fuse fits snug. Its a 30 year old truck your going to be dealing with loose and corroded electrical connections, and the worst electrical problem of all. Previous owner(s).

 

[Itali83]

I run my 87 6.2 suburban daily. After going through all the systems and making sure everything is in good shape, it’s been a great truck. Drive it all over and have been on a few 800 mile road trips. Did have to rebuild a set of injectors last summer and have a spare injection pump for just in case.


It’s like anything. You can have a garbage 350 that will soak you for lots of money, and also a good one that won’t cost you a dime. Up to you and checking things over and also being willing to go through all the systems and spend some money upfront to give you some peace of mind and reliability.


Ben