The Stovebolt Site Forums The Shop Area Engine Shop Casting mark or cracked block?

Hello,

‘59- 261, about to be installed. Drivers side below exhaust flange. Cracked or casting mark?

Thanks!

I would say crack. Does it leak coolant?

Looks like a crack to me and it's right at the bottom of the water jacket where they always crack. It might have a pile of rust sediment behind it sealing it from leaking.

Mike B

Thanks for responding. Crack it is᠁

Yea, just where one of mine cracked.

Similar crack in a Pontiac 6 cyl only it runs into a freeze plug hole. Sand blasted to grey iron, roughed up with 24 grit 1" each side of crack and sealed with Marine-Tex. Used expandable rubber plug in freeze plug hole. That was in 2010 and zero problem since.

[img]https://i.postimg.cc/348trwcL/40-Pontiac-engineand-trans-002.jpg[/img]

Yes, it's a crack, but it's repairable. Vendors on Ebay sell threaded, tapered cast iron plugs and the tap to install them. Find both ends of the crack and drill a hole to prevent it from spreading further, then install a series of overlapping plugs to "sew" the crack. Use a sealant like green Loctite on the plugs as you install them. Cut each plug off level with the block before drilling and tapping the next hole to overlap the plugs with each other.
Jerry

Bwana jim Had one at the top almost full length someone epoxied it. Never leaked. Hotrod is right "sew" it up would last aa long time.

I have a 261 with a crack in the same place. Good reason to always clean out the drain hole(s).

Ed

Thanks everyone! I’m going to weld it shut, after drilling the end studs.

Unless you're WAY more skilled than I am, welding is not the way to repair cast iron. It needs to be preheated and cooled slowly after welding. You may even need to re-machine if it warps on you.
It's just a water jacket, so epoxy or Jerry's drill-tap-plug method would be way better.
I tried brazing a cast iron engine side plate once and wound up tossing it, as it was warped so badly that there was no chance of getting it to reseal again.

EdPruss ONE of my 216's is cracked by the block drain I think from sludge or maybe casting flaw ,been like that for 39 yrs. and still OK. Have hauled a train load of wood with it .Load her to the gills dual low head for the house tough piece.

One use to be able to weld them up with ni-rod
Ron

Depending on how the crack goes on your 216, could you tap hole to next larger size?

Ed

Do you have a medium-sized boat that needs an anchor? There's a very good chance that's all the block will be good for after the welding job.
Jerry

Only way for a hobbyist could weld a crack that big would be to weld one, 1/16" dot at a time with one day in between each weld.
If you try to run a bead on room temperature cast iron, you will get spider cracks running in all directions. If you don't have an oven to put it in right after you weld it to allow for slow, gradual cooling, the weld bead will likely crack.

Just a thought, but I believe I'd drill a hole...maybe 1/8" at each end of that crack and then bevel grind it all the way across. Then I'd take a 1/16" brazing rod, measure and bend each end so they'd fit into the two holes and lay the rod in the crack. Then I'd use a flat point hardened chisel to tamp the rod into the crack as tightly as possible. Then I'd use Stay-Silv paste flux, an oxy-acetylene torch and some Stay-Brite silver bearing solder and just solder it all the way across. It wouldn't get the block hot enough to do any damage (that solder melts at a temp just below 450F) and ought to be plenty strong enough to last a long time. That solder is fine for joining dissimilar metals and you can definitely use it on cast iron. In many cases Stay-Brite is stronger than a brazed joint.

Otherwise, I'd say stitching it would be the best answer.