Cracked Block

[oworm]

Just replaced my water pump and noticed a leak at the block heater. Ive never used the heater but the PO might have as I discovered a 4 inch hairline crack! We cleaned the area and dried it with compressed air and saw coolant sweating through the crack. Is there a fix for this without going down the expensive and time consuming route of looking for another block?

 

[Agnem]

Some guys have had good luck with JB Weld. I think you may need to grind the crack out a little bit, and possibly drill a hole at each end to prevent the crack from spreading. It's going to be a pain either way. Sorry.

 

[icanfixall]

Well... It sounds like you have a big issue to deal with... Sorry for that bad news too. Getting the crack dry will be the most difficult part of this hopefull repair as posted above. I would make a suggestion to start looking for another motor or at least a block newer than what you now have. These early blocks have this crack issue. But not all is bad. Every part in your motor is the same part as found in the 7.3 motors so.... Finding a 7.3 block you can bolt it in place without any problems. International shared all the internal engine parts in both of these engines. The crank, rods, cam and oil pump are the same in both blocks. Only the pistons and rods are differant in the turbo blocks...

 

[Knuckledragger]

If it is an early engine, he needs a 6.9 block.

I agree with Mel, and further, if you are going to try JB weld, try grinding a little furrow down the length of the crack for the epoxy to have something to grab. It would be better yet if you applied it from the inside, but that is impractical. Don't worry about drilling holes or grinding, that part of the block doesn't have any stresses on it. heat the crack until you are sure there is no more moisture. Even a little bit will ruin the fix.

 

[oldmisterbill]

I agree with Mel if you can drill the ends of the crack to prevent it from spreading -if the crack started it can spread. If its a flat surface -I hava "stitched" cracks with out welding on antiques. JB weld is worth a try -but I would never trust it on a long trip.
There are several ways to stitch a crack -
1. using small pipe plugs gently start one at the end of the crack by drilling & tapping -grind flush then drill & tap anpther plug overlapping so the first plug looks like a 1/2 moon shap -doesn't have to be exactly 1/2 just a decent overlap-continue to the end of the crack.
2.Stitch with Lock-n-stitch pins. I watched an oldtimer repair a piece of cast iron with a broken out hole he stitched the broken piece back into the main casting ,when finished it was not visable.
Search "cast iron crack stitching" on U Tube

 

[Exekiel69]

Get another 6.9l (not an early one), they are cheap. You'll have spare parts.

 

[Brimmstone]

I agree with Mel if you can drill the ends of the crack to prevent it from spreading -if the crack started it can spread. If its a flat surface -I hava "stitched" cracks with out welding on antiques. JB weld is worth a try -but I would never trust it on a long trip.
There are several ways to stitch a crack -
1. using small pipe plugs gently start one at the end of the crack by drilling & tapping -grind flush then drill & tap anpther plug overlapping so the first plug looks like a 1/2 moon shap -doesn't have to be exactly 1/2 just a decent overlap-continue to the end of the crack.
2.Stitch with Lock-n-stitch pins. I watched an oldtimer repair a piece of cast iron with a broken out hole he stitched the broken piece back into the main casting ,when finished it was not visable.
Search "cast iron crack stitching" on U Tube

Seconded on the Lock-Stitch pins. I've used them myself to fix a crack at the block heater. I deleted the heater at the time also by cutting a piece of mild steel and grinding it till it fit in the hole tight then lock-stitched it in place. Couple years now with no leaks or further cracking.

 

[Black dawg]

the lock stich pins are a regular fix on the 24v cummins

 

[65sixbanger]

There is a block on the cummins motors, the infamous "53" block. The casting formula was not mixed right, and they are expected to crack. There are threads on cumminsforum and such that have different ways to fix these cracks. Stitching is probably going to be the hardest but most effective. There is a marine grade epoxy that works well with this. Ill try to find pics.

 

[oworm]

Seconded on the Lock-Stitch pins. I've used them myself to fix a crack at the block heater. I deleted the heater at the time also by cutting a piece of mild steel and grinding it till it fit in the hole tight then lock-stitched it in place. Couple years now with no leaks or further cracking.

Did you do the repair with the block still in or did you remove the engine? It seems possible to me from looking at it that it might be possible to do it with the fender and starter removed.

 

[Brimmstone]

I did it still in the truck but would pull the engine if I did another. If you do this get some very good drill bits. I used jobber length cobalts and a right angle drill to drill my holes. They show using an air drill to tap with but I did everything by hand. Yes I did remove the starter and inner fender but it was still a pain.

I'm building my original 6.9 for my 87 and will try to get pics when I delete the block heater on it. Sad part is the block heater is what killed the original engine when it came loose and fell out while driving. Our engines will get real hot real fast without coolant. Granted my pics will be just sealing the hole with a plate permanently but you'll get the jist.

 

[Rot Box]

Crap that sucks

This may be useful http://www.stamey.info/Truck/Cummins53BlockFAQ.htm If you scroll down to the bottom there is a "repairs" section with some tips.


http://www.locknstitch.com/

http://www.locknstitch.com/RepairExamples.htm

 

[Dave7.3]

Wow...I have NEVER seen anything like that locknstitch...

Man, makes you sure wonder when these days a crack like that would just be an instant boat anchor with no questions asked.

 

[icanfixall]

These block heater holes will take a standard freeze plug and seal up. No need to use anything else. If the block is cracked then all bets are off. Stiching is a lot of work but it saves a block too... Removing the block and doing the work on a stand is really the best way to repair like this....

 

[oworm]

Thing is.............. I'm not losing any coolant whatsoever which tells me the crack is small. I'm thinking of using Irontite all weather for the inside and JB weld for the outer bock