How hard can a 6.2 diesel be run?

[rs74]

Took the diesel for a drive today. This is my first diesel so everything is a little different. This truck has 4.56 gears, 400 trans and is 4wd. I ran down the road and got it up to about 55. It sounded like it was revving pretty high. I didn't push it any harder until I learn a bit more about how these engine run and drive. I don't have a tach in it so I don't know the rpm's I was pushing. With the 4.56 gears how fast should I be able to go without starting to be hard on the engine. It took a bit to get up to speed with the 6.2. I am not used to such a crawl to get up to speed.

[70chev20]

Well 4.56 gears puts you at least 2750 rpm at 55, depending on tire size. I have no idea what is acceptable cruising rpm for this motor, but considering it is a diesel, I would say that going any faster than 55 is probably pushing it.

[nekkidhillbilly]

the old green camo ones where pegged about 65

[meatwagon83]

yup 55-60 is all that truck is gonna want

[86c20]

i cruse mine at 70 with no problems thats about 3k with 4.10 and a 33 inch tire. more then that the mpg goes way down

[Idaho64GMC]

These engines are fairly weak when compared to the newer high horsepower cummins or even the 6.5 in the 90's gm's. They will do what they will do is the best way to put it. If it seems like you're pushing it or it doesn't want to do what you want it to do, then don't do it. the stock engines will break cranks if overworked, theres a lot of 6.2's in junk yards that spun main bearings or broke cranks because people use them for power machines when they were designed to be mileage machines.

[rs74]

I am running 285/75/16's which is about a 33" tire. These are about all used up that are on there now. The engine was pretty loud at 55. I am seriously going to have to look into some 3.73 gears for this truck. I don't want to be pushing it at 55 since this will probably see alot of highway. That and I am sure with the 4.56's its not going to get great mileage anyway.

[Idaho64GMC]

3.73 is the perfect gear (in my experience) for 6.2's. all of mine have been 700r4 though, I'm sure that would be a huge improvement with the turbo 400 as well

[rs74]

As much as I would hate to do it I always have a 350 and a 454 that could be put in. Still the gears would eat me alive with any thoughts of trying to keep double digit mpg's

[Idaho64GMC]

don't do it, keep the 6.2. I'm not at all trying to talk you out of the 6.2 I love that engine, Just trying to give some helpful tips to make sure you get the most out of it and love it. If treated right I've seen them with 300 thousand + miles on them.

[rs74]

Originally Posted by Idaho64GMC

don't do it, keep the 6.2. I'm not at all trying to talk you out of the 6.2 I love that engine, Just trying to give some helpful tips to make sure you get the most out of it and love it. If treated right I've seen them with 300 thousand + miles on them.

I am not wanting to. The 6.2 is part of the reason I bought it in the first place. Just figured I better get some input from guys here that have experience with them before I push it too far on accident and blow it up.

[BIG V]

I have a 6.2-6.5 detroit diesel in my wifes suburban. I have studded the heads i bought the last crankshaft i could from gm had the rotating assembly balanced mild port work on the heads, banks complete system on it. It drives like the old 396-402 in the early 70 pickups. Enough power to out drive most other trucks on the road and some cars. It pulls 6500 lbs with out any problem just like a 454 but i get 18-22 mph and 16-18 loaded. Im running a th700 r4 with 3.73 gears with 265-75-16 tires. I have no complaints and i have less than half of what one of those new trucks cost when they are a few years old. Keep the 6.2. The cranks break from poor maintenance. Change the oil every 3000 miles and put a quart of atf in the tank with every fillup to keep the pump working correctly. I have a few 6.2 diesels. my 83 van with a 6.2 had 350k when i sold it.

[Pyrotechnic]

If you run the numbers, 33" tires and 4.56 gears at 55 MPH is about 2600 RPM which is not bad at all even if it sounded loud to you. 65 MPH is 3000 RPM and 70 MPH is 3300 RPM. Not the best but I wouldn't be afraid to run these speeds.

[Tx Firefighter]

For years I was a mechanic for the Post Office. All of our two ton box trucks had 6.5 non turbo engines, TH400 transmission, and 4.56 gears.

You held them flat on the floor. All day. Year after year. Put it fully on the mat and let it scream. Never had any engine troubles out of those trucks in the years I worked there. On the entire Fort Worth fleet, we might change an injection pump per year. But no engines. They're tougher than folks give them credit for.

[old Rusty C10]

if you've read any of my previous posts you know I have two of the CUCV trucks 6.2 diesel th400 4:10 gears and the NP205 transfer case. I bought these trucks to beat on and I do, the first one at least. Currently we go back and forth about 80 miles per way per day 2 or 3 trips. I load it up with broken concrete more than bed high or soil . I haul demolition garbage with it too. My guys beat it revving it high. The truck came with a kind of miss and in the morning it sounded like a bad bearing.. I just add oil and keep on going. We did have one exhaust valve spring that went that we recently replaced but im sure that was part of the start up noises, and was bad like that before I got the truck. In short my trucks travel 55-65 MPH constantly with full loads ( overloaded) and have done well.

[andrewmp6]

If your looking for more power do some searching,Or banks does make a turbo kit for it but its 2 grand tho.

[Rubble]

The governor is only gonna let it run so fast anyway,cant remember off hand what high idle is on these things.My brothers FIL has a 88 square 1 ton 4x4 DRW with 6,2. That poor truck was drove to the floor all the time & it didn't kill it. The bigger V8 diesels ran high 20s to low 30s, Cat 3208,Cummins 555,903s.

[rs74]

Originally Posted by andrewmp6

If your looking for more power do some searching,Or banks does make a turbo kit for it but its 2 grand tho.

Not really looking for more power. Just don't want to grenade the ol 6.2. If I were to do anything else with it down the road I would entertain a Duramax or 24 valve Cummins.

[mrolds88]

Another avenue that you might want to look at for RPM reduction is a 4L80E. Get a setup from a 93 or earlier diesel setup. You may have to do some driveshaft work because that tranny is a bit longer than the T400 is. But you get the same guts as the T400 and have OD. The diesel trucks with the 4L80E have a stand alone computer to run the tranny.

[crashz]

Around 2000 rpm is the sweet spot. they get loud beyond that, but it won't hurt them.

There are those who love the 6.2L diesel. I'm not one of them, though I've owned at least one at any given time, for most of my life. They have left me stranded more than often than not.

In all fairness, it was ignorance on my part for the service I recieved. But no other engine is as finicky and as punishing as the 6.2/6.5 family. Small items can have a catastrophic effect:

Lack of a starter nose bracket = busted starter bolts/broken block
Fuel air leak = rough running = possible cause of common cracked blocks or broken cranks
V belt tension = constant squeal or burnt alternator bearings.
Timing chain stretch = rough running = possible cause of common cracked blocks or broken cranks
Injection pumps = No start/run, replace every 100K
Glow plugs = no start, burn up and swell, break off in head
Gp controllers = no start
Direct drive starters = 70 lbs of battery consuming monster.
Harmonic balancers = degrade over time, rough running = possible cause of common cracked blocks or broken cranks
Cracked heads = All seem to crack, early ones leak directly into coolant chamber, evetual hydrolock

And at 130 HP / 270 ft-lbs of torque, who wouldn't want all of those issues?

That being said, they could provide excellent fuel econemy if well maintained and in a nice light half ton. Then again, everything does when hauled by a wrecker.

Don't be scared of the issues above, but keep them in mind. Keep the fuel clean and air free. Check the harmonic balance for a loose outer ring. Keep the starting / charging system up, and make sure that little bracket is on the front of the starter connected to the block. Ask me how many blocks I've ruined by not having that piece.

[manimal]

check out..
www.dieselplace.com/forum

[joe231]

A/C 60G glow plugs=no more swollen glows. They are self regulating.

The new starters are gear reduction, way more compact and lighter weight. Neither of mine have the extra starter bracket and no cracks in the blocks.

The '85-up glow plug controllers are trouble-free in my experience.

With today's ultra low sulphur diesel, you need to run an additive in the fuel to lube the pump. I use 2 stroke oil, $1.50 a container.

I advanced the injection pump on both of my 6.2's, made a world of difference in power and throttle response.

[Idaho64GMC]

[QUOTE=joe231;6354899]The '85-up glow plug controllers are trouble-free in my experience.

That's interesting, I've had the exact opposite experience haha. my 82 and 84 that I had never had trouble with glow plug controllers, My 86 and my uncles 85 both went through several until we switched them to manual operation.

[Edahall]

My 82 Suburban with the 6.2 has 3.08's and a 700R4. It would top out at 103 mph not because of rpm's but because of wind drag.

[nekkidhillbilly]

overdrive would be the best help. but 6.2s are pretty tough. a 6.5 isnt but still id have one.