Engine Questions

[hobie237]

I don't have a whole lot of experience with these engines, so I have a couple of basic n00b type questions.

First, what type of lifespan can be expected from the engine before needing a rebuild?

I know that common problem areas involve the harmonic balancer coming apart, and I also heard something about dual-mass flywheels, but something tells me that an automatic trans vehicle wouldn't have a dual-mass flywheel to worry about. Are these concerns? Should I simply replace the part(s) as preventative measures?

I've heard there are issues with some of the blocks being weak castings. Is there a way to tell whether a block is good or bad? I'm thinking about buying a spare motor since they're so cheap, but I want to make sure I get the best I can.

I was thinking about the 6.5L repower, but it'd be more expensive than a turbo on the 6.2L. Does anybody know if the manifolds for the 6.5L turbodiesel motors bolt to the 6.2 blocks? That would allow me to run a cheaper DIY turbo setup rather than the Banks. I can do a 6.2 rebuild/turbo way cheaper than a 6.5 repower, so it just makes more sense.

Thanks for all your help.

PS- Yes, I know I don't *need* the extra power, but I don't *need* a Miata with double its standard horsepower, either.

 

[CUCVFAN]

I think this has been covered a lot, so search the archives for the turbo stuff, but the short story is: Yes, you can use the 6.5 turbo parts on your 6.2L. The balancer can be a problem, but just keep an eye on it. Rubber hunks missing from the elastomer ring are bad. Dry/cracked rubber is bad too. Stock dampers are not that expensive.

 

[hobie237]

That's the thing, a new damper is $60-$100, I got no problem just throwing a new one on if it would be a wise idea.

I did some searching, but I've found some conflicting info both here and on FullSizeChevy.com, so I figured I should ask to get the current thinking. I know from other forums that there is usually more than one school of thought, and the current state of "tribal knowledge" tends to change.

So can I assume that the auto trans models don't have the dual-mass flywheel to worry about?

Any way to determine whether it's a good or bad casting?

That's a sweet dually, BTW.

 

[Recovry4x4]

Mileage? I've had one for 400,000 before selling it

 

[gringeltaube]

Conflicting info???
I can confirm that turbo-ing the 6.2 for under 1K$ has been done a lot in my area, even if it is difficult for us to find 6.5 parts.
I've done that conversion myself in my daily driver '88 (ex)gasser K1500 4x4, installing a CUCV 6.2/ manual 5speed od. (Nissan) and 4.10 diffs on 33” tires. The only 6.5 part used was the pass.side exh. manifold. A ($650,new) waist gated Garret turbo, found on modern Mercedes Benz truck engines 352/366 (5.9l) was a direct bolt on. Exhaust is all stainless 3.5”.
I even managed to adapt a big air/air intercooler in front of the radiator (before knowing that boost pressure for a stock 6.2 should be limited to not exceed 8psi...!)
It sure pulls strong enough though, no matter if level or uphill, loaded over 2000lbs or empty.
In my opinion that motor is a very reliable workhorse with the advantage of being capable of burning “cheaper” alternative fuels too!

G.

 

[hobie237]

See, that's the thing, some people tell me that the 6.2 will be fine, just boost it and call it a day. Others tell me it's junk and I should just replace it with a 6.5. I was just wondering if there was any sort of "final verdict" that had been reached, but the more I read the more I think that both ways have their advantages and disadvantages, but in general boosting the 6.2L should be fine.

So 8psi is about as high as I should go on the 6.2? Why do you mention the intercooler like it's a problem?

 

[Westech]

I love my 6.2 in my M1009 and 08. good on fuel, enough power to move it down the high way at break neck speeds, and can make it smoke knowing the valve seals are not shot like a gasser.

 

[hobie237]

So are the cracking issues overblown? Same with the harmonic balancer issues?

 

[Recovry4x4]

6.2s are more fuel efficient than the 6.5 or so I've heard. It's been my experience too but no scientific data to back it up.

 

[gringeltaube]

...So 8psi is about as high as I should go on the 6.2? Why do you mention the intercooler like it's a problem?

I think that with that little boost air is just not heated up enough, so there is no real benefit, compared to the $$$ and effort to build and adapt the cooler + air conducts + all other mods.. Also when suddenly accelerating there is a (short) delay in response due to having to first charge the cooler and lines before pressure can build up. Combined with a relatively slow spool-up heavy truck turbo it might be the cause of initial black smoking. I did test run it once, with the intercooler cut short and could not really tell the difference regarding acceleration and power. Possibly it would help to keep the EGT down and improve a little in fuel economy for extended trips over 60mph specially with high outside temperatures...?
Sorry, all just theory here, no measurements ever done. Others sure can tell you more!

G.

 

[hobie237]

The intercooler will give you more throttled volume and thus worse throttle response, but depending on the size of the turbo and the turbo's characteristics, it may or may not be a bigger issue. How hot the air gets is less a function of the pressure being run than the insulating characteristics of the turbo, the exhaust gas temperatures, how well the turbo is cooled, etc.- as the heating is mostly a function of running the intake air in such close contact to hot parts (anything spinning 20,000 RPM+ will get really hot) and the hot exhaust gasses in the turbo.

That all said, since knock would be a non-issue (primary reason for intercoolers in gassers) the only benefit would be cooling the intake air to make the charge more dense, and how much benefit would be derived would be questionable, but relatively easily measured by taking temperature readings in the intake manifold before the turbo and then after.

That all being said, it looks like there's no crossover in the turbos- that one bank has the turbo and the other remains the regular non-turbo manifold. Is that correct? Just seems odd.

 

[CCATLETT1984]

There is a crossover, it runs from the regular drivers side manifold, over to the banks manifold on the passenger side. look at my photo album in my sig.

 

[gringeltaube]

..... and how much benefit would be derived would be questionable, but relatively easily measured by taking temperature readings in the intake manifold before the turbo and then after.

That all being said, it looks like there's no crossover in the turbos- that one bank has the turbo and the other remains the regular non-turbo manifold. Is that correct? Just seems odd.

OK, I promise to take some temp. measurements under different conditions to know what it does.
Yes, the left manifold is stock and connected to the right via that crossover pipe, in my case stainless 60mm od. And just because it was somewhat difficult to route it down between front drive shaft and oil pan over to the other side I had been considering the alternative of a twin turbo application. But then I had to fabricate custom manifolds on both sides! Maybe next time…

G.

 

[Tanner]

I used to sell reman 6.X GM diesels - we had to junk 80-85% of the blocks we received as cores due to cracks in the main webs, block sides, etc. You might get 400k out of a 6.2 or 4k out of one - it's karma, luck, black magic, voodoo, whatever, regarding lifespan.

Experience that I have with the 6.X engine is simple: They are a LIGHT-DUTY diesel engine that redline at ~ 3600rpm. (Caveat here: yes, others will post that "Chevrolet put them into 1-ton trucks" - true, but the General has done stupid crap before, and this is no different - what other diesel engine did GM have to offer??) Driven as ORIGINALLY intended, (light loads, no abuse) it *should* give you many miles of service with typical maintenance issues & an occasional desire for glow plugs/injection pumps. Keep filters changed, OLF done on a regular schedule, don't overheat it (they do have some cooling issues to contend with), they don't use dual-mass clutch & flywheel on auto box transmissions, yata,yata, yata... Yes, some aftermarket companies offer stud girdles (jury still out on effectiveness of the kits - evidence primarily anecdotal), stronger ARP stud kits, threaded inserts for the main web tapped bosses to prevent the spreading of the cracks (anecdotal effectiveness), etc. I used to have the books that listed casting numbers for the later heads & blocks on the 6.X motors that were supposedly better than the earlier castings. Later blocks & heads were supposed to contain a higher nickel content in the metal mix for greater strength. These motors weren't designed to last forever, just 'long enough' - your mileage may vary...

And before others chime in:
- no, a DD 6.X diesel isn't as strong as a Cummins 4B/Detroit 353/Isuzu 4BXX/gnat on my cat's as$, etc...
- yes, the 6.2's, IN MY EXPERIENCE of selling improved units to both civilians & the military, don't like abuse, but have a better durability rating stock than the 6.5, until the better/later 6.5 blocks came into service.
- If your intention is to drag houses off of their foundations, or my sister-in-law away from the desert bar at Golden Corral, then the major power-boosting of a 6.2 is probably not the direction you want to go in.

Yes, Minimal tweaking of the 6.2 is okay, but don't go nuts with it, unless you want to scatter parts on the road. Am I the defacto 'expert' on 6.X engines.... errrr, no - there's always someone smarter than me.

"Tanner"

 

[gringeltaube]

..... I used to have the books that listed casting numbers for the later heads & blocks on the 6.X motors that were supposedly better than the earlier castings...

Thanks for the insight. Any chance to find info regarding casting#s for the later/better versions?

 

[hobie237]

I could go for that info, too, in fact, it'd make a great addition to the FAQ.

 

[Tanner]

..... I used to have the books that listed casting numbers for the later heads & blocks on the 6.X motors that were supposedly better than the earlier castings...

Thanks for the insight. Any chance to find info regarding casting#s for the later/better versions?

Wish I hadn't discarded those casting books now!!

Some of the info can be found from the engine remanufacturers - other places on web also have some good info.

I've read that the 6.2/6.5 with the 10149599 casting number were the thickest blocks made and were produced in the 1992-1993 time frame. Some say they're the strongest of the 6.X blocks. '599' blocks were supposed to be good; discussion of 6.2 block cracks here - http://www.gm-diesel.com/vbull/showthread.php?t=24820

"Tanner"

 

[maritimer]

well for reliability shy of some user created issues my m1009 has been great i use it for pulling stumps getting groceries, patroling the family land, winching lesser abled drivers out of stucks, seducing the girlfriend on the beach, annoying the local constabulary with loud exhuast and slow acceleration. the only power mods i have done to it are cold air from passenger fender, advanced timeing, turned up fuel rate, and free-er flowing exhuast via cherry bombs, eventually i will be going up to a larger dia. exhaust pipe and doing a egar swap from 3.08 to 3.73 but its a stout truck and defintly turns heads, especially when the you pull a 6K dead weight sled without breaking a sweat hehehe

 

[Somemedic]

Advancing the timing...? Do tell!! i wanna know how

 

[Westech]

just have to rotate the injection pump a bit. nothing to it really . 3 bolts