The Diesel Garage banner

Chevy 6.2 and 6.5. Why no love?

10K views 30 replies 15 participants last post by  M123KT-450 
#1 ·
So i am relatively new to diesel. I've been playing with mud trucks for years and decided to start pullin. I hear the good and bad things about all the cummin's and powerstrokes. Yet when it comes to chevy diesel, i can't find anyone to say a good word about them all that way until duramax. So i ask, why no love for the 6.2 an 6.5? If anyone can help me out with why they are "junk" that would be awesome.
 
#2 ·
They are the lightest duty diesels offered in a pickup.

Neither is abuse tolerant, this means that virtually ANY abuse from skipping an oil change to mile overheating will shorten their life.

They are essentially the same engine with different displacements, that's an over simplification, but reasonabally accurate. They are light and return good mileage when spec'd correctly, but underpowered and short-lived if spec'd wrong or over worked. Not what you expect from a diesel, sorta reminds me of the Olds 350D :(
 
#3 ·
They are mostly popular for folks with a full size rig that are looking for better mpg than a V8 gasser. Think of it as a "Basic Transportation" engine.
 
#4 · (Edited)
they are just cheaply made. poor casting on blocks and heads, the harmonic balancers fail causing them to break cracks. I personally wouldnt take one out my drive way. (there not that bad but you get the point)
 
#5 ·
The later 6.5's aren't that bad...afterall they were used in the military HMMWV's. A little under powered (of course I was driving a 10k pound armored truck through the mountains). It's not a racing motor by anymeans.
 
#7 ·
well if tinkering is what you want to do, the 6.2 or 6.5 is a great choice. they are cheap and very simple to work on. early 6.2 engines [82'/83'] had some head gasket issues. get the uprgade headbolt, problem solved. harmonic balancers with lot of age or miles can as mentioned lead to stress cracks, or more likely a broke crank shaft. this applies to both the 6.2 and 6.5 engines. 6.2 engines will pull any load a 350 will pull, add a turbo and it will run with a stock 454, [pre vortec]. i have/had both, as well as hauled alongside others. the 6.5 is a decent puller also, stick with the mechanical engines for reliability, computerized one's had some issues. wether 6.2 or 6.5, something to keep in mind, if it has a turbo, keep a close eye on egt's. 6.5 engines have a lillte think crowned piston, but both are subject to cracking from excess egt's, too often. rings get brittle also. as for maintnance, both will hold up better then any powerstroke when it comes to poor maintance. my oldest 6.2 had nearly 400k on it before breaking a crank [ see balancer advise] , and it had seen several 12/15k mile oil changes. after nearly a million miles of seat time behind trucks powered with these engines, not a single one left me stranded. i have used them exclusively in my farming and construction buisness, hauling anything from 1500lb hayrakes to 15000lb backhoes , frequently. while i would rather use one of my fords or dodges to do the serious towing these days, i still remember the time when a turboed 6.2 had to do all the pulling, and i still use it on ocassion.
 
#8 ·
My only expierience was with a friend's truck the block was cracked around the main bearing cap bolts all of them, the rebuilder said this was common, with high mileage, hope this info helps, besides its a bow tie.............I would rather own the blue oval, what ever you do have fun with it, even if you need it for work!!!!!!!!
 
#9 ·
6.2/6.5s are not nessesarily bad motors they are just in a different catagory as the PSD, Cummins, and D max. They are more of a lighter duty engine, they have decent power, but will never compare to the heavier duty engines. And can not survive when put under the stess that the other motors are built for.
 
#11 ·
Bla Bla Bla it's simple the 6.2L nad 6.5L are of a Detriot diesel design ! ! !

Now with detriots great idea of a 2 cycle diesel they didn't have any power you used every gear. . .They leaked so bad oil changes where done almost continualy. . .
Semis that had the V- Detroits you walk threw any randum lot of trucks and pick out the DT's by the Large puddle of oil under the truck ! ! !

Don't get me wrong the 53 71 n 92 Modles of DT-diesel would live just as long maybe long longer due the very frequent oil changes as the Cummins or Cat diesels. . .DT has improved they Make HP n TQ now and they dont LEAK OIL as much or as often:happymugs

I been told the 6.2/6.5 will hold there onw as regular drive about diesel for 200K-300K miles. . .

I'm also told the Duramax ain't that great ?
"it'll haul anything you throw at it, they get up and go much quicker but around 150K its about fried ! " was the quote i heard alot. . .

I have a 6.5TD and as far as i can tell it'll tow anything a 454TBC or 427TBC could it'll just get 20mpg instead of 10mpg doing it. . .

I'm still wating to hear how those 7.8L I-6 Duramaxs have been holding up ?
they been out for good 2+ years now. . .

Mike
 
#12 ·
I have a 6.2 in my GMC, and I can tell you it should never have been approved for anything bigger than a half ton or SUV. In 170,000 miles, I have replaced the motor 3 times. My Ford 351 windsor GASSER motor has more miles on it and it's been worked harder than the GMC has. The 6.2/6.5 get great mileage in DD applications, ****ty mileage in a cube van. I wish it had come with the 454.
 
#15 ·
Those old big V6s are cool, but I wouldn't say they are better than a 6.2/6.5, not even close.
 
#16 ·
Well i'm not scared to get my hands dirty. I'm all about making something thats not so great, awesome as hell. If even to just see the look in the nay-sayer's face(s) as the motor they were all told was bad (but really dont know why) pulls away from them in a black smoggy, squirrel mincing fashion. However, i have found myself either, a 95 PSD or a 93 12 valve cummins. So i think until i get some real diesel tinker time under my belt, i'll get something like that. See my other thread for any tips you might have. Or if you think i'm making a huge mistake let me know! haha. Like i said i've been playin with gassers for YEARS in my mud truck, but i'm kinda new at the diesel stuff.
 
#21 ·
My 94, 6.5 that I use to have was great to me. It was still ticking great when I got rid of it a 270,000 miles. The tranny was starting to need some attention but other than that no probs. I drove it hard too.
 
#23 ·
Ive seen one 6.5 with 400,000 miles one it and ive seen one blow up at 62000 miles form the factory, the fact is that you never know with them. Ive seen more blow up early than last to 200,000 miles.
 
#22 ·
I wish I still had that truck.
 
#25 ·
I like my 6.5, Ive had lots of them with very few problems. My 94 has well over 200k and pulls 14k most of the miles. Dont over heat them and dont expect to do 90 mph towing and its fine. Its not a hot rod its a truck to me. I would never by a new truck when I could buy 5 or 6 K3500 6.5s for the same price.
 
#26 ·
So hows the 6.2L ? they live long ?

6.5TD's n 6.5NA's are like 8v71's n 8v91's or V-300's n V-903's if you don't run them and maintain them as they were designed to be ran ! than they won't last. . .

So anywho enough about the .65ers whats the scoop on the 6.2's ?

Mike
 
#30 ·
thats the key to these engines. run the piss out of them. they can take extended oil changes. they can take long hrs of ideling. they can take minor to even heavy overheating[ care process after they overheat detemines if they crack a head or not]. they can run with a bad injector or inj pump for many miles. these engine can take a LOT OF ABUSE. what they cant take is being lugged. having air in there cooling system. running long with a weak harmonic balancer. not getting warmed up before the rpms get up. or excess egt's for to long. even the n/a 6.2 can see egt's in the 1200* range when lugged bad. as mentioned there has been casting issues with some of these engines, some years were better then others. after having 12 6.2/6.5 powered gm trucks, only one has actually failed me. it broke a crank at nearly 400k miles. the cause was running the original balacer . they are not for the most part designed as well as a cummins or ih engine, but then again for what it cost to replace a cummins or ih, you can buy 2 of the gm's.
 
#27 ·
Part of the problem with 6.2s/6.5s is a friggin' cast crank.
Never understood GM: you buy a 350 gasser in a one ton you got a steel crank, but the diesel had a cast crank ?!?!?

Even the 48 horse VW Rabbit diesels had steel cranks.

A diesel should have a crank that will bend and not break.
 
#28 ·
Well i kinda want to go out and buy an old 350D now haha. The 6.5td is something i am going to look into on my next project, as of right now i bought an 85 f-250 6.9l idi. Plain on doin a turbo per bank of cylinders pump an injector mods, dpi and probably some better bits in the trans. (its a 4 speed). Although, i need to wait a bit so i can heal up, i cut off a finger at work. Soooo for right now im in gather info mod. If you have some that would help me out, let me know in the pre 1994 6.9 and 7.3 forum. I have tons of time to read up haha. Thanx!
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top