Main bearing web cracks and girdles

[tequilaiam]

Is this a common problem on the j-code engines like it is on the civy versions?

As usual, the interwebs are full of conflicting "info". Some places say it's an issue on all the 6.2/6.5 blocks. Others say the j-code valves are smaller and the military blocks have more nickle, making them less suseptible to the cracking. Is it a common issue with CUCVs?

If so, how do the girdles sold by DSG work? I've read several people on here install them but no real comparisons or even anecdotes about if they prevent the problem or not. They look easy to install, are they? Just drop the pan, remove the old bolts and install the new posts, screws and girdle or is it more complicated than that?

Thanks!

 

[Anubis8472]

Well the real problem is that no one can say whether the girdles 'work' or not in the real world.
You may install the kit and never see any cracks.
Who can say that you would have if you had not installed it?

In theory, the girdles 'should' 'help' to prevent cracks.
The manufacturers also claim that they prevent existing cracks from worsening.
Again, in theory they should help.

I hadn't read anything about 'valves', I thought the cracking issue had to do with to much machining for the bolts. The fix in later blocks was to reduce the bolt diameters.

I think I recall the price tag being somwhere around 150 right?

I figure that's not bad if it does it's job. So I plan to put one on after I drop the pan (likely this spring) to inspect the bottom end and try to clean up some seepage.
It's one of those things that 'can't hurt'.

 

[tequilaiam]

I read that about the bolt size too. The valve issue, per my understanding, is lower pressure differential when they open and therefore less vibration on the crank. Valid? Who knows.

Price is about $180 which seems steep for what is essentially 2 bent pieces of sheet steel and bolts.

 

[ken]

The only small valves i have seen are from 82 and 83 coarse thread injector heads. On "C" code engines.

 

[chevyCUCV]

From what i've read If you have a crack free block it will stay that way.
Im not sold on girdles as doing anything really.
All 6.2/5 can crack, Some dont and those are the keepers
82 is know as red block, supposedly with higher nickel, but none of those would be in cucv's as they started in 83. Also 82's had larger exhaust valves which they downsized because of cracks in the heads.

 

[Anubis8472]

I read that about the bolt size too. The valve issue, per my understanding, is lower pressure differential when they open and therefore less vibration on the crank. Valid? Who knows.

Price is about $180 which seems steep for what is essentially 2 bent pieces of sheet steel and bolts.

Yeah, it's one of those things I wish I could fab myself.
Unfortunately a 500% markup seems to be the norm these days.
When I got my new flatscreen a few years back I was going to purchase one of those wall mounting brackets. They wanted around 120 bucks for it. I actually pulled it out of the box and went up to the guy at the counter. "120 bucks for this?!? It's a peice of stamped steel with 4 screws!"
Off topic... anyway, I was outraged.

For the girdle ... it's something I wouldn't be comfortable making with a hacksaw and a hand drill. So unless I happen to pick up a drill press/band saw etc. before then, I'd consider it a one time cost and 'suck it up'.

Of course if you know someone with the tools.
Primary concerns would be getting the holes centered 'perfectly' you don't want to be adding any stress, and clearance. Some new bolts and torque to spec.

 

[Tanner]

The valve sizes used have absolutely nothing to do with cracking blocks. Nothing. Nada. Zilch.

The blocks are same (to my knowledge) between C-code & J-code 6.2 engines. Differences were in the heads & tuning, maybe cams; I'm too lazy to dig into it any further to find out.

All 6.2/6.5 blocks may crack. Or they may not. Was it a balancer issue that lead to a cracked block or crank? Who knows. It's anecdotal. Mere speculation as to what caused the sh*t to go 'Boom'.... The 'higher nickel content early blocks' legend is just that - legend - until someone reverse-engineers the metallurgy to confirm it. J-Code engines were not specific to the military; the mil versions had a bit different state of tune & increased HP/TQ numbers, but were identical in hard-parts content to the civvy J-Code motor.

The girdle is actually not sheet metal; it appears to be angle iron or milled bar stock -

'Tanner'

 

[kapnklug]

I just installed the DSG stud girdle, cost $170 to my door. Check out post #15, 4th pic.
http://www.steelsoldiers.com/showthread.php?74264-m1009-turbo-lift-buildup-2.html

 

[tequilaiam]

IF they are cracked, is there anything that can be done? I saw some pics online and wondered if silver solder would flow into the cracks or hit it with some brazing rod. Using a torch to heat it to that point could mess up the temper though.

 

[Warthog]

Many of the diesel website already talk about the cracking and how to fix it.

The Diesel Page - for the 6.2L, 6.5L, and Duramax 6600 (6.6L) GM Chevrolet and GMC diesel engines.

Go to the BB forum and read the stories and solutions.

 

[Tanner]

By the time you muck around with trying to 'fix' the cracked block. you've pissed away time & money. When I worked for ______ & we we're remanufacturing the 6.X motors, close to 80% of the core blocks we took in were junk & we'd simply use new blocks.

We had a special insert that we'd put into the blocks to stop the cracks from spreading: tried this 'fix' on a couple teest trucks - don't recall the outcome, though.

There are still quite a few usable 6.X blocks around; search for a usable one.

'Tanner'

 

[idM1028]

YAY! I get to use the non-destructive testing books I just paid $250 dollars for! And I'm renting used because I'm broke!
As far as cracks in the casting straight from the factory go, from what I'm finding, the most common cause is hot tears/ shrinkage cracks. Basically, if a casting is composed of light (less metal) and heavy (more metal) sections the light sections solidify and shrink faster than the heavy sections. This creates stress between the light and heavy sections and can cause a tearing of the metal (crack) at the junction of the light and heavy sections. These are generally open to the surface and can be detected visually. However, if they're not caught in the inspection process at the factory, well... If you're worried about it, I'd have the block magnafluxed. This will show surface and just sub-surface cracks.
And as far as cast iron goes, it's actually pretty weak when it comes to stresses (tension, compression, shear loads, and torsion) when compared to say, structural steel for example.
As far as adding nickel, it is added to steel and other metals to increase ductility (the property that allows a metal to deform permanently when loaded in tension I.E. pulled apart), among other things. My understanding is that the cracking problem was solved in LATER military 6.5 (See: HMMWV) blocks by adding more nickel to them as well as a main bearing girdle.
Now for bigger/smaller bolts: Yes, you may be adding more metal to the block (and strengthening it in the process) by going to smaller bolts, but if your smaller bolts are made of the same material as the bigger bolts, you're taking strength away from those bolts (smaller cross sectional area=less part strength)
As far as welding cast iron, it can be done. However, if you go that route, I'd suggest you find a d*** good welder. Just because it can be done doesn't mean it's easy...

 

[Gunfreak25]

I recently spoke with a friend who came down from Canada, the man has lived and breathed anything 6.2 related for the past several years. I won't say he is an expert because there are far too many of those out there these day's. But from what I gathered with talking to him and from the research I have done on several boards, the general consensus seems to be that hairline cracks in the webs are no reason to scrap an otherwise fine running engine. Another man I spoke with in Canada has also used 6.2's and 6.5's since their introduction also agree's with this. He feels the girdles not only help keep a block from cracking, but keep a cracked block from getting worse. And he makes his own "improved" girdles that he feels offer more structural rigidity than the aftermarket one listed above. He goes by the name Turbonator over at the DP forums as well as a few other Diesel forums.

If I recall, the 2 reasons for the webs cracking is because Detroit wanted to keep the overall height of the engine as short as possible, to do this they had to clear out extra room in the web area to allow for piston skirt clearance. The 2nd reason is of course the 12mm bolts which left less meat around the edges.

For what it's worth I will be installing a homemade "5 stud" girdle just like Turbonators in the not too distant future.

Question: Main Bearing Stud Girdle Question - Diesel Place : Chevrolet and GMC Diesel Truck Forums

http://www.dieselplace.com/forum/showthread.php?t=438483

 

[Tanner]

YAY! I get to use the non-destructive testing books I just paid $250 dollars for! And I'm renting used because I'm broke!
As far as cracks go in the casting straight from the factory go, from what I'm finding, the most common cause is hot tears/ shrinkage cracks. Basically, if a casting is composed of light (less metal) and heavy (more metal) sections the light sections solidify and shrink faster than the heavy sections. This creates stress between the light and heavy sections and can cause a tearing of the metal (crack) at the junction of the light and heavy sections. These are generally open to the surface and can be detected visually. However, if they're not caught in the inspection process at the factory, well... If you're worried about it, I'd have the block magnafluxed. This will show surface and just sub-surface cracks.
And as far as cast iron goes, it's actually pretty weak when it comes to stresses (tension, compression, shear loads, and torsion) when compared to say, structural steel for example.
As far as adding nickel, it is added to steel and other metals to increase ductility (the property that allows a metal to deform permanently when loaded in tension I.E. pulled apart), among other things. My understanding is that the cracking problem was solved in LATER military 6.5 (See: HMMWV) blocks by adding more nickel to them as well as a main bearing girdle.
Now for bigger/smaller bolts: Yes, you may be adding more metal to the block (and strengthening it in the process) by going to smaller bolts, but if your smaller bolts are made of the same material as the bigger bolts, you're taking strength away from those bolts (smaller cross sectional area=less part strength)
As far as welding cast iron, it can be done. However, if you go that route, I'd suggest you find a d*** good welder. Just because it can be done doesn't mean it's easy...

Nice! Somebody got a new textbook for Christmas!

'Tanner'

 

[idM1028]

Nice! Somebody got a new textbook for Christmas!

'Tanner'

Oh yeah. If I had known they were going to be that expensive, they would've made an AWESOME Christmas present! The AWS structural steel code book that I need is close is around $380 new. I still need to buy my toolkit, but that can wait for a bit. Around $270 or $280... the worst part is, I've already got some of the stuff I need for the kit, but you save a bit more by buying it altogether. For example, a set of individual VWAC gauges: $80. On another note, the school also has a GM program and a couple diesel programs, but they're geared towards ag and over-the-road diesel. I've heard if your car is messed up or needs some maintenance, you can take it to the appropriate program and they'll work on it as a sort of hands-on project. I wouldn't mind having the GM kids rebuild my engine... after I do some mag particle on the appropriate parts down in the lab of course

 

[prh]

I am in the process of building a 6.2 turbo. Is there any concensus on use of a stud girdle. In my research I've heard that they work, theyre junk, and one guy said he spun a bearing after installing a commercially available stud girdle. Also, heath stated that his studs are essential for any high performance builds. Here are my thoughts and observations from dismantling an engine and inspecting the bottom end. Stock bolts do not extend any where near the bottom of the threaded holes in the block. This is good if youre using stock bolts as they should not bottom out. Stock bolts however do not engage all threads possible and are probably weaker than studs regardless of fastener strengtg. I'd recommend use of studs in all builds wether a stud girdle is used or not. From measuring main caps it is observed that the dimension from mating line to the face where the bolt seats is not consistent between caps. Use of a stud girdle without machining caps at the bolt seat for consistent thickness could lead to the girdle not letting the main bolt to fully transmit its clamping force to the main cap. Based on this, i tend to belive that installation of a stud girdle, if not properly done, could lead to bearing failure at one. If anyone has had experience either good or bad, please respond for the those of us who can henefit from those who have gone before. I dont want to "touch the stove" if someone can tell me that it's hot.

 

[richingalveston]

When adding a turbo to a 6.2, a stud girdle cannot hurt as long as it is installed correctly. The basic idea is to spread the load on the caps from the firing cylinder to the non-firing cylinders next to it.
I spent a lot of time researching it also.
From what I have found you want a full girdle and not just the 3 stud version and yes if for some reason the caps are not even, shims are better than milling or bending the girdle.

the girdle must be flush with all caps on install or you will be creating a negative effect on some of the caps.

My 2 cents.
I was going to turbo my 6.2 but after determining that I would add all this extra stuff, I decided to go 6.5 gep so hopefully I don't have to do this again for the life of the truck.