What are the 6.2�s most common problems and their solutions?

LonesomeT444E · Jul 12, 2008

What are the 6.2’s most common problems and their solutions?

I really need some help here. I know nothing about 6.2’s and locating information is more difficult than I thought it would be. I would like to know anything and every thing that is prone to fail as well as any special tips I should be aware of to prevent failure. I do plan to upgrade as much as I can, so feel free to shout those out at me as well.

detroitdiesel · Jul 13, 2008

With the 6.2, from what i know, the common problems are the the fact that it has a timing chain which can break and cause serious engine damage (DSG offers a gear timing set conversion to fix the problem), the IP's are not know to be that reliable, but not to terrible, they are gutless, they can blow head gaskets (any engine can but these blow allot of them. To high of compression maybe??) the bottom end mains are know to crack (DSG offers a stud girdle kit to help prevent the problem), and the crank is known to break.

Marine 1 · Nov 24, 2016

marine 1

ALSO: the guy is right when he says that the (earlier?) 6.2 GM diesel engines were hard on 1. Water Pumps... 2. Mechanical Fuel Pumps... 3. Electric diesel fuel lift pumps... 4. Glow Plug controllers... I've had four (4) GM diesel pickups and have had to deal with the above problems... PLUS, I've had considerable problems with the brake system. If a diesel truck sits for a short while, the brake system (master brake cylinder push rod) will tend to start sticking, which causes the brake system to NOT release all the way... problem? The brakes will start to stick as though the calipers were sticking. Before i knew better, I paid two mechanics over $400 to replace (twice) Autozone's rebuilt brake pressure unit. Remember that GM diesel trucks do NOT use a vacuum operated brake system... but rather the brake system operates off the power steering pump.

Good Luck Gentlemen...!

marine 1

High Sierra 2500 · Jul 13, 2008

The motors are pretty decent if you don't run them too hard, and if you keep up with the maintenance you shouldn't have too many problems, but the truck around them is different. The engines go through a water pump every so often, and an injection pump as well, but we're talking a lot of miles for either of those. The main thing about the engine itself that goes more frequently than the rest of the stuff is the mechanical lift pump... Costs maybe $20.

The other thing that causes problems is the glow plug system, it can be a little troublesome.

farmer0_1 · Jul 13, 2008

we still have many on the farm and they are way more reliable than most any motor out there. we treat them fair and get great service out of them. out of them all they have close to a million miles if added all together and yes i have installed a couple of new motors only after the old ones had over 200k on them. now i know you can run many motors more than that , but not many of this vintage. cummins didn't start until 87 or so i think. yes some of the things mention in earlier post are true. we have had no head gasket problems. mostly glow plugs and fuel issues but only after alot of years of service.

LonesomeT444E · Jul 13, 2008

The gear to gear kit is the first thing on my list. But it kind of stops after that. Are there any upgraded solutions to the glow plug Injection pump prolbems? I plan to draw a lot of power from this engine once I get the common problems worked out.

High Sierra 2500 · Jul 13, 2008

No, there's not a lot you can do. The injection pump isn't what I'd call a problem, it's just one of the things that wears out (takes a LONG time though - I'd say we're usually talking at least 100-150K miles). The glow plugs can be upgraded to self limiting 60Gs to prevent them from burning out, and you could wire up a manual controller for increased reliability, but you don't have to do that.

Honestly, it's not the best thing to try and push a lot of power out of...

LonesomeT444E · Jul 13, 2008

I wanted to give a little more ass becuase it is going to be a play truck. I also like to experiment when I iuld something. At what point should I look into a stud girdle?

Also, are there any differences bewteen the military version and civilian?

farmer0_1 · Jul 13, 2008

got to agree on pushing alot of power out of one of these is not the best bang for your buck. buy a early 12v cummins and drop it in i see complete rigs on occasion for 2500 bucks.

jmay2174 · Jul 13, 2008

FarmerO_1 has the right idea. Even better would be a Duramax. They should be getting cheaper as the price of diesel keeps going up. The 6.2 design technology is over 30 years old.

Croatan_Kid · Jul 13, 2008

There were C-code engines and J-code, the Cs were EGR and the Js were non-EGR. All of the military motors were J-Code 6.2s and have 155 HP!

You can turbo these motors, but most agree that it's 10 pounds of boost max with the 22:1 compression. Lower it a bit and you can run slightly more boost. I've seen some seriously built 6.2s that were twin turbo'd, but that's too much money. I've seen quite a few people but 6BT Cummins' in CUCVs with an NV4500 5 speed and an NP205. Only thing is the Cummins is HEAVY, close twice the weight of a 6.2 which only weighs (I think!) 250 pounds more than a small block.

turbovanman · Jul 14, 2008

You guys are really down on 6.2's, lol. For what they are/were, there a damn good engine. Sure they had issues but what engine doesn't.

If you maintain, do some basic mods, maybe a gear ratio change, you'll be happy. I put over 30,000 km's on mine last year with NO problems except Thursday when it **** the IP but meh, it was time anyhow. OH, its got 130K on it now,

It will be getting turbo'd and I expect it to do exactly what i want, is tow my trailer much better-its a dog now but without the gears and turbo, its to be expected. Unloaded, its got decent power and I weighed the van last week, 5500 lbs. I don't need to spend $1000's on a Cummin's or Dmax or 10's of 1000's on a new truck,

LonesomeT444E · Jul 14, 2008

I have always wanted to biuld a 6.2 powered triel rig. I know they are realiable and with a few upgrades can be made a little better. I already bought a 12V for a conversion on my wifes' F250. And the engine was a lot cheaper than all of the doner 6.5's I looked at. I do not plan to pump more out of the engine than it can hadle. But I would like to make it a little better. I figured going after its common problems was a good place to start.

0lee · Jul 14, 2008

Manual G60 glow plugs are nice, you need good batteries and battery connections ... Maybe upgrade to a good electrical fuel pump, depending on what you have eventually upgrade the fuel filtering; install a fuel pressure gauge. Check the balancer (preferably replace) and the crankshaft pulley, maybe improve the air cleaner (and use AcDelco filter elements), maybe put in new injectors and maybe stud girdles. Have the injection timing checked/set correctly. Make sure you have the starter bracket installed.

That's pretty much all you can do to make it better, besides knowing well what you have and (preventive) maintenance.

LonesomeT444E · Jul 14, 2008

Thanks. That sounds like it would get me off to a good start. One thing I have not been able to confirm though, if there a big difference between mine and a civilian model?

0lee · Jul 14, 2008

The starter and the glow plug system are set up for 24V; the axles and the seats are different, there have been IPs that were improved to run on kero/jet fuel, there is no sound insulation (get some earplugs for driving), maybe some other details ... There is a myth about the military versions having thicker sheet metal.

LonesomeT444E · Jul 15, 2008

So for a trail/mud/play truck I did good. But I am not going to get any more power than I have right now. Am I correct? I do not want to go through the hassle and expense of changing the charging system.

0lee · Jul 15, 2008

LonesomeT444E said:
So for a trail/mud/play truck I did good. But I am not going to get any more power than I have right now. Am I correct?

Yes --- you can carefully give it a bit more fuel, advance the timing a bit, make sure that it's easy for the engine to get air and have a good fuel supply to the IP (very important) --- but provided that everything else is in good condition, you don't get much more power than you get.

I do not want to go through the hassle and expense of changing the charging system.

That's good ... It's an old engine, and chances are to blow it up by charging it --- not immediately, but it just puts a lot more stress on the engine ...

And you don't need more power, not for 4wheeling. What you need is ground clerance, straight axles and torque to the wheels to keep them turning. You already get good axles and a lot of torque (in 4low) --- do the math, afair you get about 300 ft/lbs on the input side, geared 1:2.48 (TH400) and 1:2.61 (NP208) and 1:4.10 (diffs), that makes a factor of 26.54. 300 ft/lbs times 26.54, divided by 4 wheels makes 1990 ft/lbs per wheel. Just fill in the correct values: http://www.florida4x4.com/tech/gearcalc.php. If you switch to an SM465, the factor is 69.98: a crushing 5248 ft/lbs per wheel.

More power would mean either same torque on the input side but higher engine speed, or more torque but the same engine speed. In any case, with more power, you can break things --- like axles, driveshafts, diffs --- more easily.

If you have sufficient ground clearance and are able to keep the wheels turning, where can't you go? You may find that the limit is the weight and size of the vehicle, but not a lack of power, not any time soon.

LonesomeT444E · Jul 15, 2008

Well siad Olee. I have been biulding off road rigs for a while. Just about all my lessons have been hard learned. I do agree that with the propper suspension gearing, and running gear engine power is of little consequence. I'll to a few monor mods, like the ones mentioned. But other than that I will just keep it running and well maintained.

0lee · Jul 15, 2008

Sounds like fun

I wish the conditions for offroading were better here --- there are some places where you can go, but it's too hot to do anything outside, and it's dry anyway. Maybe in the winter ...

LonesomeT444E · Jul 17, 2008

When I get home we plan to move to a more off road friendly state. That is a big junk of our life style. I am hoping to have a rig that will take us way out into the back country and get back with out any worries.

0lee · Jul 18, 2008

All the more reason to make it street legal ... Which state is offroad friendly?

MillwrightJesse · Jul 18, 2008

montana
parts of washington
oregon i think

akdiesel · Jul 19, 2008

Talking with a mechanic freind of mine. He said that there have been some issues with the crank. What happens is since they usually came with the T400 and highway speeds the crank would spin too hard and brake. The cranks were not completley balanced.
Is this true?
I have had two 6.2 3/4 ton pickups and they both were/are very good engines.

LonesomeT444E · Jul 19, 2008

I have heard somehting similar about the crank.

montana
washington
oregon

Those are on ly list of possibles. Two more are Alaska and Coloroda. (sp) If we live some where like that, I may have to make it street legal. Oregon I think is my first choice right now. If I could talk my wife into moving to Alaska that would be my first choice.

0lee · Jul 19, 2008

Wow, Alaska ... I'd love to drive up there some time, but I'm not so sure if I'd want to live there for long.

The crankshaft, well, some seem to break, some seam not to do that. There is some believe that when the balancer wears out, the crank becomes more likely to break. --- Some time ago I had some vibrations from the engine and found that I had two injectors leaking, one on each side. After I fixed that, the vibrations were less. I installed a new balancer and replaced the worn-out crankshaft pulley with a used one that isn't worn out, and since then, the vibrations are gone. So I'd say balancer and pulley are important. If they cause vibrations, that obviously does put some stress on the crankshaft and the bearings.

High Sierra 2500 · Jul 19, 2008

Eh, yeah, there have been crank failures with the 6.2. But the same is true for most other production engines. I'd say its not an abnormal failure rate myself. If anything I'd say they have higher than average reliability.

LonesomeT444E · Jul 19, 2008

SO just like anything else, if I take care of it and repair prolems as they arise, I should not have any problems.

I am hoping to drive to Alaska when I get home for good. Just the road trip itself is something I am looking forward to.

0lee · Jul 19, 2008

LonesomeT444E said:
SO just like anything else, if I take care of it and repair prolems as they arise, I should not have any problems.

Exactly --- you may have to fix a lot of things besides the engine and maybe some "engine things" when you get the truck because things age and wear and the previous owner(s) didn't care, but once they are fixed, you're good for another 10 years or so. You can have bad luck, like the crankshaft breaking, but that can happen with other engines as well.

Things that wear out on the engine, like IPs, lift pumps, vacuum pumps, glow plugs, injectors, balancers, pulleys, accessories are normal wear. Freezeplugs, I guess, are somewhere between normal wear and neglected maintenance ...

Fortunately, you can get parts relatively cheap and fix the problem yourself rather easily. There's some room under the hood so that everything is reachable, much of it very easily. Compare that to a Ford Powerstroke --- it's not as bad as it looks on pictures, but compared to a 6.2, it's close to a nightmare. A Duramax seems to be even worse, as far as I can tell from the pictures I've seen.

I am hoping to drive to Alaska when I get home for good. Just the road trip itself is something I am looking forward to.

Indeed --- that's what it is about anyway, and it's called traveling. Most people don't (want to) travel but only be somewhere else and totally miss the point of it.

See, you'll have to get the truck street legal to make that trip. It might be a bit small to sleep in it with two people, but it can be done. Install a parking heater to keep it warm inside, get a compressor fridgebox, a dual-fuel Coleman stove (gas stoves suck for outdoor use) or a MBU, a lot of blankets and good sleeping bags and a canister for water, and you're (almost) good to go

akdiesel · Jul 19, 2008

In 2005 I bought an '82 3/4 GMC 6.2 that had, at the time, 132,000 miles. It also has the 400 tranny. It was in Seattle. I drove it up the Alcan to Anchorage during the winter. No issues at an average speed of 65 mph. Great on fuel also.
I was the second owner and he took good care of it from what I could tell.
I still have the truck and the only thing I have done to it mechanically is change over to synthetics. No leaks.

What are the 6.2�s most common problems and their solutions?

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