6.2 Broken Crankshaft Revisited.

[Recovry4x4]

High load at low RPM causes lugging.

 

[85CUCVtom]

High load at low RPM causes lugging.

So like during a tractor pull? Or pulling a trailer slowly uphill?

 

[Two Stroke Madness]

Anytime you are towing or climbing a hill if your giving it more throttle and not gaining any road speed you are lugging.

 

[Tinstar]

That's what I thought but had not heard that term before.

Thank you

 

[rustystud]

This whole thing about "lugging" a diesel engine causing a broken crankshaft is not true. Diesel's by their nature are made to Lug. The reason GM's 6.2L diesel engines had problems with the cranks was due to the Harmonic Balancer, the weird dual flywheel, and the Accessory Drive balancer going bad. GM corrected these problems. Now is there legitimate reasons to blame GM's quality (or lack thereof) of machining ? I would say "Of course" . Just look at the whole "web" issue. GM is notorious for getting products to market without thoroughly vetting them. Just look at the TH700R4 transmission ! I have a book of factory recalls and modifications for this unit alone. I have also thought GM's line boring for the crank was another culprit. But be that as it may, lugging an engine has never caused a crankshaft to break as far as I have ever heard.

 

[Two Stroke Madness]

I believe the solution to this problem would be to have the entire rotating assembly machined and balanced as close to perfect spec as possible. I've read that the cranks are a little out of spec from the factory, and that the pistons and rods are not weight matched very well.

 

[reaper556]

I believe the solution to this problem would be to have the entire rotating assembly machined and balanced as close to perfect spec as possible. I've read that the cranks are a little out of spec from the factory, and that the pistons and rods are not weight matched very well.

basically balanced and blueprinted? I wonder what that would cost?

 

[fitz]

5 pages deep and not 1 comment on how to maintain or repair a CUCV.

 

[TGP (IL)]

5 pages deep and not 1 comment on how to maintain or repair a CUCV.

I didn't think that's what this thread
Is about?
Tom

 

[cucvrus]

How to maintain and repair a broken crankshaft on a CUCV by CUCVRUS.
1.) Shut off engine when broken crank is detected.
2.) Open hood and remove hood. Have assistance to avoid serious injury or death.
3.) remove negative battery cables.
4.) Follow guidelines outlined in TM for removal and replacement of crankshaft in the 6.2 engine.
5.) Problem fixed with post 50.
5 pages deep and not 1 comment on how to maintain or repair a CUCV.

 

[Two Stroke Madness]

basically balanced and blueprinted? I wonder what that would cost?

I've had crankshafts for gas V8's balanced for $60. I think the whole blueprint job costs about $120 ish. With a little know how and a scale you can weight match the pistons and rods yourself.

 

[Two Stroke Madness]

5 pages deep and not 1 comment on how to maintain or repair a CUCV.

5 pages deep, but on the back cover it finally tells you how to prevent unnecessary repairs.

 

[CUCVLOVER]

Here is another idea. Maybe the fact of being a 30 year old, rattling, diesel, that was probably not built to be tight as a Lamborghini engine and is just old could be part of it. Sometimes turds impact the propeller and that's that. It's a old, possible had a hard life, engine. That's just a way to look at it. Could the crank have been cracked from day one? Who knows, someone could have dropped it and just sent it on down the line anyway, or maybe the inspector wanted to get to lunch or take a dump. The possibties are almost endless.

 

[rustystud]

The 6.2 engine is a good basic engine, not as good as the 6.5 but still good. Now if someone wanted to spend the money and have this engine "balanced" and "blueprinted" they would have a better engine but still not as good as say a Cummins. This topic is about the same as the deuce "Multifuel" . Do you want to spend good money trying to make a engine that has issues into something that is great or do you take that same money and buy a more modern engine that is known to be good from the start and still has good ability for improvement plus easily available parts. Unless your a "purist" and are trying to keep the truck as "stock" as possible, I would say go with the newer engine.

 

[nyoffroad]

I've had crankshafts for gas V8's balanced for $60. I think the whole blueprint job costs about $120 ish. With a little know how and a scale you can weight match the pistons and rods yourself.

I have two 6.2's sitting in my driveway right now, one is bone stock the other I rebuilt(stock) with the exception of balancing the rods and pistons (rings on) I also 'ported and polished 'heads and manifolds. It is the smoothest and quietest 6.2 I've ever seen. I do have to admit tho I never owned a brand new truck with a 6.2 so maybe they all were like that when new but I doubt it.
As far as lugging a diesel goes, it may put a lot of stress on the crank but so does starting out on a hill with a load! You can't help that, the bad part as I understand it is with the old mechanical engines like the 6.2 is that not all fuel is burned and the fuel washes oil off the cylinder walls. Also in the 'old' days with high sulphur fuel the sulphur would combine with moisture in the crankcase and valve cover and form sulfur dioxide (think acid) and would corrode soft parts like bearings.
Just my .02