Experience with Cast Iron Block Repair - Cracked

[JacksFordParts]

I'm looking for real world experience for repairing a FE block with a sizeable crack on the side of the block. I picked up a very well built 431 Stroker a while back from a guy who pulled it because it was cracked in the water jacket on the side of the block.  It's about a 3 inch long crack running at an angle up the side.

It doesn't intersect the freeze plug and I'm pretty confident in repairing it.

I know lock n stitch is probably the best option. But I dove headfirst into researching epoxies and there's a ridiculous amount of options and avenues. Reading online has just made it seemingly worse to make a decision on what to use...

Belzona seems to be the king but isn't easily available quickly. This is going in a convertible Fairlane and I'd like to be cruising ASAP. Emp, A&B and other companies make epoxies that seem like a few notches up from the JB weld world.


I will eventually just switch out the block for one that is sound.


Any success stories or experience shared would be greatly appreciated.

Jack

[jayb]

I agree that Lock n Stitch is the best option.  I always worry about epoxy's ability to handle heat cycles in a large defect area.  A 3" crack repaired with epoxy would make me nervous.  For what it's worth, you could also get the crack welded and then cover any porous areas with epoxy, which would probably survive better in an application like that.

[blykins]

It needs to be pinned/welded.

Next time you're through this way, I'll give you Ray Shepherd's phone number.  He's about 1.5 hours south of me.  He will fix it and you won't know he fixed it.

[428kidd]

Take it to Ray have him fix it and be done with it and ready to rock!

[My427stang]

Strip it, send it to Ray, reassemble....it'll have more value when complete, even if it's planned to be temporary.  Beyond the cost of repair and shipping, all you have is the cost of a gasket set if it's pretty inside.

Ray does beautiful cast iron work, he'll decide if welding or lock/stitch is better and more importantly will pressure test it when done, not only on the crack you know, but look for others that may be doing something less visual.

[JacksFordParts]

Thanks fellas, I've been using Ray for years, Lance turned me onto him many years ago, he is truly a wizard. But... I really don't want to have to take it apart. Was hoping I could band aid it to be able to use it in the car this summer.

[My427stang]

So if you really want to play, and your install and pull time doesn't matter if it fails...drill the ends of the crack to stop travel, grind it nicely and V out the crack, maybe etch the metal,  and lay something in there. I'd be concerned about expansion and contraction with a patch on the wrong side of pressure, but might hold for a while.  Wish I could help with better stuff, but in the end, I think prep and travel control likely more important.

If you can't find the ends of the crack, I think it will travel and probably a waste of time

[JacksFordParts]

If I were to have to strip it to fix it, I would just switch the block out. It's just a 390...

[Joe-JDC]

Short term, AB would work if you can clean it with lacquer thinner of acetone beforehand.  AB is intended to be used under water.  JMO, but if you get it clean, it will work.  Joe-JDC

[JacksFordParts]

Thanks, Joe, I needed a brand to try and use.  Time is an issue on this and that is why I want to try the epoxy route vs other options.

The Belzona product is used in Nuclear reactor facilities and is seriously amazing stuff, but not easy to find for some reason. Per testing it does not shrink, expand or shift in any way once its set.  I am really surprised it is not more known in the muscle car community.  I have heard good things about AB.

[frnkeore]

Per testing it does not shrink, expand or shift in any way once its set.

Since cast iron does shrink and expand, in the long run, it isn't good.

I calculated that 3" of cast iron, will expand .0025 with a 130°F increase in temp.

If it's a flat area, I think a better way, using epoxy's, would be to D&T the ends of the crack, 10x32, then put a piece of at least 16 ga steel, at least 3/4" wide across the crack and attach it with 10x32 button head screws. Add one or two 8x32 button heads to each side of the steel, for a more permanent repair. 

The difference in expansion between CI and steel, over 3" is only .00005

[oldiron.fe]

       most repairs mentioned should work well- best for time/expense-i had a small marina/mercruiser repair service in wis. -repaired many blocks/ex.manifolds-  make sure you find the end of the      crack or any repair may not work well!!    drill- v-notch crack clean well - used devcon product-never had a fail-marine motors get the he-- beat out as may run at full rpm for long periods                  also same process  except heat area with a small torch-used small a/c welder with good cast iron rod-short 1/4 inch weld --peen a lot with chipping hammer (a lot) to repair -- never failed      the repairs were made from freezing people missed or did not clean drain plugs while getting mud in system in shallow water         john

[pbf777]

        One would need to look at the positioning of the crack, attempt to understand why it cracked and it's relationship to stress points within the casting.   

        On the exterior sides of these blocks one of the greatest causes for cracking seems to be from the tension pull from the outside head fasteners, which is quite significant, particularly with the use of aftermarket fasteners of just too great a load capacity that the block was never intended to experience; and this perhaps coupled to a weaker than should have been casting as delivered from the O.E.M., which with heat expansions and contractions, this just pulling the block apart.  If this were the case here, it would seem obvious that "glue" probably isn't going to work, and since the "pinning" process would provide even greater forces in spreading the block open, neither sounds to me to be a good option.

        I'd say there probably isn't going to be any "simple" fix; welding is probably the best option to "try", the better the capabilities of the welder the more likely one might experience success; but as one whom has done such work, do realize that success here still relies greatly on the parent material that one is attempting the fix upon; bad castings with some welding work are still 'bad' castings.   

        Scott.

[Stangman]

This was many years ago in the early 90s. My dads father bought a 67 RS Camero plane Jane 327 2bbl new and it’s been in the family since. We did a restoration on it and had machine work done and when shop was taking side drain plug out block cracked and like yours about three inches. Like you car was done and immaculate didn’t want to take it apart. With a wiz wheel grinded a line at the end of the crack on the one side and grinded a line through the length of the crack which went into the threads of the drain plug. Not sure which one I used but I JB welded the crack and JB welded the drain plug in and let it sit for 2 days. Put water in it and let it run after about 30 minutes had a slight leak near were I grinded to stop the crack. I carefully grinded down just that spot and redid it and  sold that car in 2019 and it still didn’t leak. My dad didn’t drive it a lot maybe 3-5000 miles in all those years but sold it not leaking. Why not just get another block especially when they are so plentiful. Everything on that car was original except for one cylinder head that cracked in the 70s when my cousin Annmarie was driving the car for a couple of years. In the 70s it’s just a car.