Technical Is my block junk? Freeze crack.....

We ran a 350 with almost the same crack, in a 55 for a while. Cleaned the crack, slight V, and some JB Weld. Ran it like that for some time. Your results may vary.

 

Ni - rod then marine - Tex epoxy , did a friends 350 boat engine in 1981 , been fine since

 

JB Weld is your friend, its cheap and easy. I've used it for years and never had a bad result.

 

There are a lot of power plants and other manufacturing facilities that will sware the Belzona products can mot be matched...

 

Look online for a company called Lock and Stitch in Turlock CA...They repaired my hemi block...Don't try welding it till you talk to them if you want it fixed but being a Chevy it might be cheaper to get another block...

 

A business around the corner when I was an apprentice did this all the time, it always had engine blocks and other casting in the shop and had a pretty regular turnover. When done a quick machine of flat surface(s) and then a rough-over pneumatic scaler on the casting and you wouldn't even know that it had been repaired.

 

I had a crack very similar in a 409 block many years ago, patched it with JB weld. I no longer have the car but its still around. I talk to the guy that bought it from me occasionally, its still holding.

 

Wonder how much it costs to have that Lock N Stitch procedure done?

 

It can be fixed in a number of ways....but why? The time you spend to have it repaired is a crap shoot. I have welded ( cast iron and aluminum) blocks and heads, transmission cases and exhaust manifolds. But take a close look at the block in the second image and you will see that the casting is bulging outward. This will flex every time the engine is heated up and can recrack.
MILLIONS of SBC blocks have been produced since 1954, unless it is a MD or DZ block, replace it.

 

Just a thought...if the coolant/ice slurry had enough pressure to push the outside of the block casting far enough to crack it...it was also applying the same pressure to the coolant sides of your cylinders probably also creating distortion that could affect ring seal.

I would run it while searching for a replacement standard bore block, bore it .030 and use your internals. You will be into it for the cost of a gasket set, used block and a bit of machine work. Good luck.

 

Welcome to the 350 crack club. I bought what was thought to be a good block. Rebuilder found the very same crack. Engine two I got from the builder. Put it in ran it a summer then in the spring following year found another crack at the same spot. Builder found me another 350 crack free and rebuilt it. Fingers crossed for this one!

 

Must be a weak spot in the casting on these blocks? Wondering if a minor crack was already there and this past winters freeze just opened it up?

 

had a crack like that one decades ago in a small block, drilled a hole of either end, v'd out the crack a bit and filled it with jb weld. Sold the car years later still holding.

 

I think you are correct. Weak spot in casting. I do not think your block froze, it just happened to start leaking now. Who knows how long ago the crack started.

JB weld, weld it, whatever you choose.

 

Throw some black pepper in the radiator.

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I'd say that is the best plan. A good block sealer and drive it while you hunt down a replacement block that you can have pretty well prepped before you pull the engine. That way if you do tear into it it won't be down for a long time. The block could be bored and ready for the final honing to fit the pistons before you pulled the engine saving quite a bit of wait time.

 

You also gotta buy a new set of rings for your pistons...

 

I have spent a large part of my work life repairing boilers and pressure vessels where we would chase the cracks, grind them out & weld them back up. Pretty straight forward process in mild steel.
If it was mine & I thought it was the only crack. Lower the antifreeze well below the crack & take a Dremel or die grinder with a small burr to groove it to give a good area to bond the JB weld in. Clean it well with acetone then pack it in and over the area with JB weld. Give it a couple days & then do a wet pressure test to see that it is holding and that there are no other leaks.
I worked in large maintenance shutdown events in an Alberta oil sand refinery where our team was responsible for the inspection, maintenance and repairs on large heat exchangers. The engineers specified Belzona for repairing the heads and tube sheets to extend the life of the equipment. Belzona works but my experience is that it is expensive. It was bought it in large volumes with the deep pockets of major oil company. It might be more reasonable if it can be purchased in a small unit. JB Weld has been around & developed a good reputation. About 20 years ago we had an oil cooled circuit breaker that leaked on start up & the electrical engineers would not allow a weld for repairs. They asked me how to fix the leaking weld. I suggested center punching the pinhole closed, clean with acetone, rough up the area, clean again then place a fillet JB weld. That worked and is still there. The tech rep from GE showed up a week later & the electrical engineer asked how he would have repaired the leak. The GE rep told him that he would have done the same. An hours work & JB Weld is a reasonable cost to see if the engine is going to live.

 

Agree, I can't see the parts costs and massive LABOR hours to replace the bare block on something this simple. Like the thing would leave you stranded on a long trip if it did fail? Hell no, just loosen the radiator cap so it's not under pressure and drive it home. (if it ever leaks again)
.

 

How much heat can JB weld take? The rams horn manifold collector sits about a 1/2" away from the crack.....

 

The crack is close to some good heat.
The JB Weld site says that it is good to 550F.
https://www.jbweld.com/collections/metal/products/j-b-weld-twin-tube
There is a high heat version that is good to 400F continuous & 550 intermittent.
https://www.jbweld.com/collections/automotive/products/highheat-epoxy-putty
The water jacket is right there conducting the heat away so the block would be in that nominal 190F neighbourhood. There is a half inch so there is some space for air circulation.

 

Big trucks get cracks pinned all the time ck with truck drivers/truck stop on who to call, often they can be done in the vehicle.