Good fix for bottom end issues

[Missy Good Wench]

Hello to all
New here but not to the diesel boards.

I recently started on a project of stuffing a diesel into a 92 Burb 4x4 along with a MOPAR 4 speed overdrive. (YUP you read that right MOPAR )

I tore down a "Good" 6.2 only to be met by the infamous main web cracks.

AWE S^&T
I was brooding over this issue and contemplating how to deal with it when I learned of Lock N Stich

Now many folks have posted stuff on the boards about the threaded pin devices that they make but I had not heard about the thread inserts.

Some research revealed a local rebuilder that uses these inserts and has for several years to repair the cracked outer main bolt holes.

More digging also turned up that these guys dont do the service as an "out patient thing" only what they build.

Hmmmm I looked up Lock N Stitch and got them on the phone. Not only do they sell the tooling and inserts but have a special set for the 6.5/6.2 application.

They were very helpful and answered all my questions.
The info I have gathered from users is that there have been no failures after the inserts are used to repair a cracked hole.

The Lock N Stitch insert, unlike a Helicoil is fully self contained and not a loose coil. Also the outer threads angle up like a hook and the harder the pull on them the more they try to close the crack and pull things together rather than spread things like a wedge (Normal threads)

I ordered the tooling and some inserts and then the fun began.

I could not get a block (Heavy) onto my mill table so I designed a plate and other goodies so I could do the drilling and tapping with a mag drill.

The task is easy and takes a fairly short time to dril, tap and then lock the insert.

The inserts cost about $9 each

I have lined up a buttload of blocks to fix for some local shops so I can pay for the tooling.

Here are some pix of the operation. The platform drill plate that just gives a solid work place. The insert kit. The finished hole. Now I did use a spotfacer to drop the surface of the area slightly below the original mating area to be sure the main caps seat properly.

Best

MGW

 

[DieselCash]

Thanks for the info
Very interesting!

 

[Slim Shady]

I have been using Lock N Stich for about five years now. Have done a few head repairs with their kit and have used their cast iron repair kits for a couple of projects.

Excellent company and support: the other place and Page kind of PO Poed the idea when brought up. Glad someone else finally took the time to research them. Their products work as described, and have an excellent service life.

I guess old ways die hard and new ideas are even harder to accept. Welcome to DTR we have an open communication policy here and welcome new ideas.

 

[Missy Good Wench]

Far too many folks believe that if its works and does not cost an arm and a leg that it must be too good to be true.

The whole principle of this idea is very sound.
Obviously we all want our blocks to be perfect. Unfortunately sometimes it can't happen and I for one don't have the huge $$$$ amount to buy a new AMG with the built in girdle.

Keeping the old Iron running is a good thing me thinks

MGW

 

[jmiller]

MGW,

Welcome to DTR, nice to see you found us over here.

 

[Sunshine]

MGW,

Welcome to DTR, nice to see you found us over here.

"X2"

 

[davo727]

Yeah, Glad to see you migrated over here MGW.


Dave

 

[daustin]

Good to see ya over here Robin!!
Don

 

[TurboTahoe]

Very interesting, MGW. Thanks for sharing. Here's their website - examples are interesting... http://www.locknstitch.com/RepairExamples.htm

 

[Missy Good Wench]

Its too bad that this system has not been promoted much.

The concept is so simple yet very sound.

best

MGW

 

[NVW]

Its too bad that this system has not been promoted much.

The concept is so simple yet very sound.

best

MGW

I don't know if it's the same system but around 1980 I saw blocks repaired like this in college. Leo

 

[6265 racer]

Missy,

I have heard of this thread repair method, but have never seen it or known anyone who has actually used it. You seem to be quite impressed with it and your comments have piqued my interest. Have you or do you know those who have enjoyed success with it in the 6.2 / 6.5 mainline? Anyone with 50,000 or more working miles on it?

We used the old Heli Coil inserts on a high output engine years ago and one that had no cracks. We did it in an effort to spread the stud load over a greater area by way of the much larger thread engagement area these offer. It never failed, so we considered the operation a successful one-------but this one you refer sounds interesting.

 

[Missy Good Wench]

I learned of this repair process from a local engine rebuilder in Portland Oregon.

The shop has been using this procedure for several years and now that almost every used 6.5 block that comes in has at least one crack they have had a long run with zero mainline failures while using this repair.

The difference in the FULL TORQUE insert is that the insert is solid and not a coil. The inner threads are the standard thread as is in the block.

The outer threads are tapered up toward the top of the hole (The end the insert came in from)
Also the threads dont have the same shape on both sides as do regular threads.
The insert is torqued in with a thread locking sealant plus a little pin is inserted down through the threads in between the insert and the casting to lock it in.

As the torque load is applied the tapered threads actually try and pull the hole together instead of spreading it apart.

Think of it as stuffing a Christmas tree into a sack and then trying to pull it back out.
The threads angle up just like the limbs on the tree.

Once the terrific wedging action is stopped the original cracks will not progress any farther.

The company says that the fix can be used even if the crack is down into the web.
I wont do the repair unless the cracks are confined to the depth of the threaded hole in the block.

I am advocating doing all 6 outer holes when doing a rebuild just to be safe and preempt cracks from starting.

Many folks have used studs with success as they dont apply near the wedging action on the block when they are threaded in by hand with red locktite and then the nut torqued.

The best part of the insert is that they actually pull the crack back together and strengthen the area.

Cat is using this technology on some of their huge pit trucks in the wheel stud area.

(797 Super pit truck)

I wont say that this fix is better than a "new and better designed block" but it is a good fix and can save many otherwise good 6.2/6.5 blocks from the scrap heap.

So many blocks show a couple very small cracks that are not even visible without die or magnaflux and off to the heap they go.

About an hour or so with time for coffee and a donut and all six holes can be repaired and ready to go.

The one caviat is that the block has to be out, apart and completely striped out.

Once finished the block has to be completely and carefully cleaned and washed out to be rid of all tha cast iron particles from the drilling and tapping process.

Hope this helps

MGW

 

[davo727]

Last weekend I had sent some questions to locknstitch via email- I asked if the cracks need to be stop drilled or if a stitch pin should be installed at the end of the crack. Also asked what if there are cracks on the front and rear sides of the same web from the same hole? I received an email back on the same day from the CEO:




Yes our Full-Torque inserts have repaired thousands of cracked main bearing bolt holes in the 6.5 GM blocks. It is not necessary to install a stitching pin at the end of the crack. When installed the bolt holes will never crack again or any farther.

If the cracks turn at the bottom of the bolt hole towards the bearing bore then we stitch that part of the crack only, (not common) It doesn’t matter if there are two cracks per bolt hole and they go all the way to the bottom. In this case nothing but the insert is required. There has never been a failure that I am aware of. Most of the big rebuilders install them in all of the center holes where they normally find cracks whether they are cracked or not to prevent them from cracking in the future. The end bearing bolt holes don’t normally crack as far as I know.

Thanks,

Gary J. Reed

CEO
LOCK-N-STITCH Inc.

1015 S. Soderquist Rd

Turlock, CA

95380

800-736-8261

209-632-2345 X244

Fax 209-632-1740
www.locknstitch.com

www.fulltorque.com

 

[davo727]

In case anyone hasnt seen the way they crack here are mine on a 1995 141 block I was given with the parts truck.
I have been tied up with stuff and havent had time to tear down the other 2 engines I have to see if they are cracked or not. Working the next 12 days straight too.

 

[Sunshine]

davo727 ... i`ve never seen the way they crack, so i hope mine are OK...thanks for
the pic`s..& thanks for keeping every thing tidy thats Flying in the Air , take care with the 12 days...
/Paul

 

[TurboTahoe]

Great post, Missy -

Your explanations really clear up how it works. Frankly, some better diagrams on their website would probably help as well. (They need some better marketing folks). I hope neither of my 6.5s are cracked, but if it comes to that time, I'll likely be looking you up, MGW!

Thanks,

-Rob

 

[JiFaire]

'Way to make a Splash, Robyn! Nice post!

 

[davo727]

'Way to make a Splash, Robyn! Nice post!

Yeah, we like Robyn!, Robyn rules!