Cracked blocks

[Powerstroked162]

Is the casting of the 6.7 block too thin?

I was just being a dik. The 6.7 has a CGI block from the factory IIRC. Just super weak rods that usually window the block, rather than it cracking of it's own issues

It seems the second stud from the rear on either side of the block is where they have been cracking. The pictures of the block Haller put up are identical to what I've got sitting in my shop now. One is cracked on the drivers side and the other block in the passenger side. They split horizontally with the crack crossing the stud area. One of these blocks cracked on the very first torque.

I've got a 2010 truck here with a cracked block and one out of an 09.

The problem with using block sealer is that the crack is going to keep growing under heat cycles and stress of driving the truck. Eventually it WILL leak again.

Even if you fill the block it will not keep it from cracking. It will just keep the coolant from running out the crack because there is block filler in the way.

Like I've stated in the other threads. I believe that when these blocks were cast that the sand core moved and caused what we call "core shift". This basically means that the core of the mold moved a little when the block was poured and the result is that there is some areas that are weaker because they were left thinner than originally designed.

This has happened on other blocks and is not uncommon. Ford Motorsports A460 blocks had a bad batch of core shift that got through to the public. People were blowing engines up because the cylinder walls were thin in some blocks. You'd be running down the drag strip and no warning your block would blow out a cylinder wall and trash a $10-20k (or more) engine. People were scratching their heads till they started sonic checking their new blocks and finding that they had core shift resulting in thin cylinder walls. I dealt with a lot of these blocks.

That would be the only reason why these blocks cracking is so unpredictable. They could have a bad sand mold setup that is not stable. Couple that with trying to lighten these blocks as much as possible to save weight and material cost and you have a recipe for disaster. It may only have happened once in every 200 blocks at the factory. Enough that with more and more people studding their trucks it becomes more prevalent. We are just finding all the weaker ones.

Good point.

.

 

[Meniacal_Mark]

Yeah the 6.7 has a cgi block, and you're right Steve those rods look like they came from a 2-stroke.

 

[Fast-6.0]

I really doubt you will get it down to a casting number. I have seen an early 08 block crack, 09 block, and 2010 block crack. Erik's block wasn't cracked, we did it to seal, if it did crack. My block was a practically new 08 block, torqued it with Custom Age studs and it was fine. Tore it apart to change pistons and on the second go round it cracked.

I put sealer in it and its been fine but once I pull the heads again it will be a problem, so I will just fill it when the time comes.

 

[Highroller54]

that's it, i'm filling the impressions around the head bolt hole in with a stick welder lol

 

[gman1]

I really doubt you will get it down to a casting number. I have seen an early 08 block crack, 09 block, and 2010 block crack. Erik's block wasn't cracked, we did it to seal, if it did crack. My block was a practically new 08 block, torqued it with Custom Age studs and it was fine. Tore it apart to change pistons and on the second go round it cracked.

I put sealer in it and its been fine but once I pull the heads again it will be a problem, so I will just fill it when the time comes.

Do you think the crack will keep growing once they start or will the hard block stop it?

 

[Big Angry Hillbilly]

Without goin through the whole thread the maxx has a different bell housing pattern also.

 

[Meniacal_Mark]

That's the least of problems if the maxxforce 7 was possible to use.

 

[Highroller54]

I wonder how low you would have to go on torque to not risk cracking the block and if you lowered it would studs still be better then tty bolts to keep the heads down.

 

[Meniacal_Mark]

Either way I think it's only a matter of time if your block is gonna crack, it's gonna crack.

 

[01PSD]

Either way I think it's only a matter of time if your block is gonna crack, it's gonna crack.

:whs: BUT if lower torque values can be used, or unnecessary values avoided... maybe the problem can be kept at a minimum

 

[Highroller54]

You could be right but my thinking is the factory head bolts don't seam to put enough pressure on the block to crack it so it must be the extra force from a non tty stud torqued to a high spec that does it. So if that spec/force was lowered........

Does anyone have a pic of a 6.4 and 6.0 deck they could post up?

 

[Meniacal_Mark]

If you lower tty, will the studs stay in? Something to mull around

 

[Ipkyss]

What was the torque spec on Elite studs in 2011? I kinda remember 195? Sounds like this is something that comes from the thought of tighter is better.

 

[Dzchey21]

My truck wouldn't handle load at 190 soon as I was over about 800 on fuel it started puking

 

[madman1234509]

What did you do to remedy this? Apply more torque on the same studs?

 

[Dzchey21]

Yep they are at 325 with arp lube.
My block is cracked tho I had coolant running up the stud. Fixed it with paste for now I'll fill the block if it keeps doing it or just get another junk yard block.

 

[madman1234509]

using arp studs as well?

 

[Dzchey21]

No elite studs

 

[madman1234509]

So you torqued to 325 with elite studs? Ive never used them but if I recall that seems like a pretty high value for elite studs. Wasnt that arps old torque spec? Could be a possibility as to why it cracked. If elites studs dont stretch like an arp stud due to the material, the torque value was too high?

 

[Meniacal_Mark]

I think he meant he retorqued them to 325 after 190 didn't work.