Well as 6.2/6.5 owners, many of us have opened up our beloved little diesel only to find the "Dreaded Main Web Cracks"

Recently I started on a turbo diesel project for a Burb I aquired.
The engine tuned out to have a Metric buttload of cracks in the lower end.
Geeeez, looked like a map of the LA freeways. :eek:

I scrounged up a older Red Block as a foundation to work on but it too had one crack on number 4 main.
This crack was short 3/8 to 1/2 inch long and well inside the depth of the hole.

I had heard of a company locally (Portland Oregon) that was repairing cracked 6.5/6.2 blocks so I went to see them.

They are using the Lock N Stitch full torque inserts.

Futher investigation revealed the full story on this nifty little repair system.

The outer threads on the insert are angled up so the harder the bolt is pulled (torqued) the more the insert pulls the hole in on itself.

The local shop doing the repairs does not offer the service on an "outpatient" basis but only on their own rebuilt engines.

I decided to order the tooling and get set up.

This weekend I machined a steel plate (1/2 X 12 X 14 Inches) to bolt to the pan rail with countersunk bolts to allow the use of a mag drill to do the work.

I located six 1 inch holes over the outer main bolt holes to allow access to the area.

The work was easy and went smoothly.
The plate took several hours to get ready (needed to be sure it was perfect before I dropped the hole through it)

The mag drill was located with a pilot that slipped into the exisiting threads.
Next the drill provided with the "Kit" was run down through the hole and slightly deeper to allow the "Kit" tap to do its job.

The Inserts are then threaded into the holes with an anarobic compound and finally pinned in place.

The reports are that the fix is permanent and that no failures have occured since this has been in use.

We shall see.

This technology is being used by Caterpillar and others as an OEM so if these folks are impressed it certainly has my attention.

I will get some pix of the finished block soon but here are some pix of the tooling and such.

Well as 6.2/6.5 owners, many of us have opened up our beloved little diesel only to find the "Dreaded Main Web Cracks"

Recently I started on a turbo diesel project for a Burb I aquired.
The engine tuned out to have a Metric buttload of cracks in the lower end.
Geeeez, looked like a map of the LA freeways. :eek:

I scrounged up a older Red Block as a foundation to work on but it too had one crack on number 4 main.
This crack was short 3/8 to 1/2 inch long and well inside the depth of the hole.

I had heard of a company locally (Portland Oregon) that was repairing cracked 6.5/6.2 blocks so I went to see them.

They are using the Lock N Stitch full torque inserts.

Futher investigation revealed the full story on this nifty little repair system.

The outer threads on the insert are angled up so the harder the bolt is pulled (torqued) the more the insert pulls the hole in on itself.

The local shop doing the repairs does not offer the service on an "outpatient" basis but only on their own rebuilt engines.

I decided to order the tooling and get set up.

This weekend I machined a steel plate (1/2 X 12 X 14 Inches) to bolt to the pan rail with countersunk bolts to allow the use of a mag drill to do the work.

I located six 1 inch holes over the outer main bolt holes to allow access to the area.

The work was easy and went smoothly.
The plate took several hours to get ready (needed to be sure it was perfect before I dropped the hole through it)

The mag drill was located with a pilot that slipped into the exisiting threads.
Next the drill provided with the "Kit" was run down through the hole and slightly deeper to allow the "Kit" tap to do its job.

The Inserts are then threaded into the holes with an anarobic compound and finally pinned in place.

The reports are that the fix is permanent and that no failures have occured since this has been in use.

We shall see.

This technology is being used by Caterpillar and others as an OEM so if these folks are impressed it certainly has my attention.

I will get some pix of the finished block soon but here are some pix of the tooling and such.

I hope it works out. Should there be a concern for future cracking just deeper down int he main web?
I honestly can't see going through this on a block that is known for cracking when an updated block is out there. Your case may be different as you are doing all the work and are able to do so, but if you have to pay a shop to do all this it may not be worth it.

I assume the crack you are referring to follows a main bolt.

If so, I would have no fear of doing exactly what you're doing. I'd even think about just putting a set of studs in the bottom end.


Updated blocks at a reasonable price are few and far between. I got lucky and got a 2001 block but it had previously blown up. It mangled a piston completely and did some damage to the pan rails and the bottom of one cylinder.

We have done the proceedure for quite a while. No comebacks yet, but we never do this to a block that has multiple cracks on one web, longer than 3/8" or any that you can physicaly feel. The ones you can feel already have too much core shift to salvage. I have also used blocks that have had the cracks ground out, properly heated and spray welded. That worked too but was very expensive, and of course did not do anything to prevent cracks from appearing in the future.

I attended a seminar on this repair and the "Buzzword" from Lock N Stitch was this, If the crack is not more than a short distance out of the bottom of the hole then the repair will eliminate the original cause and prevent the crack from continuing to spread.

The spreading action of the bolt threads is tremendous and the outer hole area is also subject to an extreme amount of dynamic forces as well.

Once the stress is taken off the area the reports are that the fix is permanent.

Lock N Stitch tells me that even if the cracks can be felt that it can be repaired this way and it will survive.

I will not do any that sees the crack more than the depth of the hole and or having one that has spread open.

The block I am using on my project rig has one small crack but I did all 6 holes just because it will take the stress off the rest and assure no future failures in this area (So it says in fine print) :rolleyes:

The secret behind these inserts is that the harder you pull on the bolt the more it pulls the hole together and actually strengthens the area.

Novel idea that has been around quite a while just not well known.

MGW

Very cool MissyGW, Anxiously awaiting repair pics, Thanks, Dave

I will see if I can get a few pix today of the center main area of the little creature.

To add more info to this discussion.

Picture a log that is 10 feet long and 3 feet in diameter, now start driving a wedge into the end of this log at its outer edge.

It does not take very long and the log will split all the way through its entire length.

This is basically what is happening to the main webs on the 6.5/6.2 blocks.

The installation of the reverse thread insert reverses the spreading action and replaces it with a pulling action that tries to pull the hole in on itself.

The repair not only stops the crack from spreading but strengthens the area.

If the mainline is straight and bearing clearances are good there should be no issue even if the crack has spread some.

I have seen a few of these blocks that cracked at the sharp corner of the register where the main cap fits.

This sort of issue would be fatal as far a I am concerned and I would discard that block.

Best

MGW

Ok got more pix.

shot of the finished block
Shot of the block with the plate sitting on the bottom end
Close up of a finished hole
Close up of a custom spot facer I set up.

The spotfacer is 13/16" and I designed a special pilot that was made from a 12mm hard bolt and has a 1/4" shank.
The pilot is threaded into the hole and the spot facer is allowed to spin on the pilot. The practice assures that the new threads are not going to get damaged.

I set the spotfacer down into the block .030" to be good and sure that the inseret was not above the saddle surface at all.

During this procedure I noticed that the fit on the main caps is very strange.
The area around the inner bolts sits hard on the block but the area between the bolts had little contact (very dark rough surface) The cap was again hard on the block at the register area (outer most point)

This contact pattern was found on a couple other blocks I have so I am going to speculate that it is a normal thing for these engines.
To be honest I have never paid that close of attention before.
Now that I have my little paws into this thing in such an intimate way I have paid close attention to details all the way.

I am very confident now that this repair is as good as it can be and that the block is again quite serviceable.

I am going to proceed now with the cleanup and the reassembly.

Hope this is usefull to others.

MGW

Robyn, for whatever it's worth, -all the caps on both of my 599's exhibited the exact same thing as what you mention.

I did spend a fair amount of time "tuning-up" those surfaces with WD-40 and a stone. I also double checked the mainline bores before and after "tuning" the caps and registers up and saw no measurable change whatsoever.

I'm not sure it made any difference or not, -but I did it anyway.

I need to get up to the ranch and check that thing out!

All the best,
Rich.

Ok got more pix.

shot of the finished block
Shot of the block with the plate sitting on the bottom end
Close up of a finished hole
Close up of a custom spot facer I set up.

The spotfacer is 13/16" and I designed a special pilot that was made from a 12mm hard bolt and has a 1/4" shank.
The pilot is threaded into the hole and the spot facer is allowed to spin on the pilot. The practice assures that the new threads are not going to get damaged.

I set the spotfacer down into the block .030" to be good and sure that the inseret was not above the saddle surface at all.

During this procedure I noticed that the fit on the main caps is very strange.
The area around the inner bolts sits hard on the block but the area between the bolts had little contact (very dark rough surface) The cap was again hard on the block at the register area (outer most point)

This contact pattern was found on a couple other blocks I have so I am going to speculate that it is a normal thing for these engines.
To be honest I have never paid that close of attention before.
Now that I have my little paws into this thing in such an intimate way I have paid close attention to details all the way.

I am very confident now that this repair is as good as it can be and that the block is again quite serviceable.

I am going to proceed now with the cleanup and the reassembly.

Hope this is usefull to others.

MGW


Very impressive repair.Great job Missy!:)

Thanks guys.

Rich
This little monster should be a winner.
I think the odd patterns on the caps is a result of the iron moving around some during the many duty cycles.

I was really paranoid about the inserts not sitting below the surface as if they were even slightly above this could cause serious issues with the main clearance and the added stress on the block could easily defeat the whole purpose of this exercise.

I think the next block I do (have 4-6 for customers now) I will keep the spotface to about .005-.010 deep

Best

MGW

So are you : Missy and Jason saying if there are cracks on both sides of the same web at the same outer bolt hole that the block is trash?

I just found that on a 1995 141 block that was thrown in with a parts truck I bought, need to clean it up more and get some dye penetrant and go over it closer.

I also have a 96 141 engine and another unknown # in the 92 parts truck I just drug home. I need to tear those 2 down still. Maybe one of those 2 will be good-(yeah right) Dave

If all three blocks are cracked I will be irritated and have to decide:

1- just use main studs, main girdle bars and run it
2- get the tooling to do the repair inserts- I have a milling machine
3- look for crack free block or china block
4-give up and put big heavy inline 6 diesel in truck

Is any kind of stop drilling or repair insert done into the side of a main web at the end of a crack? Thanks, Dave

Missy: How tall are the inserts you used? Do they have the internal threads in them that the main bolt or stud threads into? Dave

They are only about 3/4" long. They have external threads to hold the insert in the block (and hold it together like Missy said) as well as the internal threads to secure the main cap bolts to.

There is no extra drilling or pinning done when the inserts are installed. The insert is designed to pull the block material towards the center of the insert, preventing outward stresses that a bolt and threaded hole cause.

What do you think about the crack on both sides of the web deal?

Also would there be a benefit to using an insert for 10mm bolts instead of 12mm?

Would the insert outside dia be smaller therefor removing less metal from the web?

I would really hesitate to use a block that is cracked on both sides of the main web. Any chance you have a picture or a measurment of how long the cracks are?

I do not think there is much, if any advantage to the smaller bolts. All of our experiences here have pretty much proven that the blocks with the 10mm bolts are just as prone to cracks as the older blocks with the 12mm bolts. I doubt there would be much difference if one was repaired to the same specs.

What if one was to splay the main caps? Would you think it (the repair) would need to be done and then drill for the splay? Or just do this repair and stud it?

I will get it cleaned up and post some pics and measurements. Gonna tear the other 2 engines down too and ck them for cracks

OK pics arent great but they show whats up: I was mistaken, there are 2 cracks but they are not on the same web .

The #2 web lt side front has a 3/4 in crack.

The #3 web rt side rear has a 1/2 in crack.

Edit: In the second pic thats not a giant black crack in the middle of the 2nd from the bottom main bearing saddle, I just went back out and wiped it off and it was just grease.

Hey Missy and Jason: How do the cracks in my block compare to what you all have fixed. I have one 3/4 in and the other is 1/2 in. Thanks, Dave

I would just throw it together and run it. I didn't even look on the 6.2L that I just finished putting together tonight. I figure if it's been fine for 15 years... oh well if there are cracks.

Nice work, Missy!

What do you mean by 4-6 for customers? Are you a professional wrencher?

-Rob