The Stovebolt Site Forums The Shop Area Engine Shop Cracked block

First start and run after 40 years revealed an engine block crack drivers side behind the manifolds.
I would hate to use any kind of internal sealing products. Other than welding up the crack, has anyone tried grinding a groove down the crack and using 2 part epoxy like "Marine Tex"?

A couple of guys recently have reported success in sealing cracked blocks using JB Weld. MarineTex is a similar product and would likely work OK. There are lots of epoxy products, some even claim to work underwater. I've found that MarineTex doesn't have a tendency to sag like I've seen with JB Weld.

Hope you can get it fixed.

Someone patched a cracked in the same place on my truck decades ago. It was a pretty sloppy job - probably an in-service repair when the truck was still used on the farm.

It looks ugly but it doesn't leak.

Marine Tex is highly recommended by a couple guys here. When it starts to get tacky, press a piece of sandpaper into the repair to give it the texture of cast iron.

Thanks so much for the encouragement. Marine Tex will be my choice.

I used the old liquid glass product on a froze up 350 and turned it into a circle track e gine 👍🇺🇸😁😁

A friend of mine let a 350 freeze up and it actually cracked in the vvalley. JBwelded it up and drove it for years.

Its worth a shot to try imo 👍👍👍👍👍

This recent thread has some additional discussion you might find helpful:

https://www.stovebolt.com/ubbthreads/ubbthreads.php/topics/1503828/need-some-help-cracked-block.html

In addition to veeing out the crack, drill the ends of the crack to prevent it from spreading.

Sodium silicate does not work with the addition of ethelyne gycol(antifreeze).

Ed

I just sealed up about an 18 inch crack in my 54 3100 that had set out in a field in Alabama. I had about a 1/4 inch separation in the middle. Used the metal JB weld that comes in a tube. You mix it my kneading it in your hand. Not a pure fix but a lot cheaper than a new engine.
Good luck on yours.

T Doug post a picture of your repair.

Here's the right fix- - - - -expensive, but effective. Overlapping tapered cast iron plugs threaded across the crack.

https://www.ebay.com/itm/254255895210?

Jerry

Jerry: how thick does the metal have to be at the crack for those to work?

I don't understand how those don't leak between each plug. The head in the picture they show obviously needs to be machined smooth but it seems like there'd be small spaces between the plugs and threads.

Otto,
Notice how the plugs overlap? They're installed one at a time, with part of the previous one drilled out and threaded for the next plug. Yes, there's a tiny crevice between each, but no more than what would be between a single tapered plug and the native cast iron.

Obviously not a job to be done with a hand held drill.

Not a crack but I did a fix on a Cat dozer engine years ago, with JB weld that is exposed to the coolant. I think it was now over 7 years when I had seen the fellow that owned it, that fix was about 20 years old and it was still running and sealing just fine.
JB Weld is great to use around coolant and antifreeze it does not degrade it.

The plugs are installed with a sealant like red LocTite, and the repair is pretty much leakproof. If the casting is at least 1/4" thick they work pretty well. Yes, a hand drill motor is used, with a piece of square key stock with evenly spaced holes in it as a drilling guide. The holes are drilled slightly over 1/4" apart, threaded and plugged, and then holes are drilled and tapped between the plugs after the first set ofl plugs are ground flush with the surface of the repair. The result is a series of "figure 8" shaped plugs that overlap and seal against each other. The repair in the photo must have been done by Ray Charles or Stevie Wonder! A somewhat modified version of that procedure is called "Lock-N-Stitch". Look up the you tube videos on that system. The L&S process tries to make crack repair "idiot-proof". Oldtime machinists usually had enough common sense not to make rookie mistakes with the more primitive repair plugs.

www.youtube.com/watch?v=Pq0wfU4ZaKk

Jerry

I will post that pic when I get home Otto.. I meant to do that before but lost track with everything else going on..

The lumpy part is where I used my thumb to press the JB tube epoxy in to fill the cracks. The lighter color is the two part liquid JB weld I coated it with after the other had cured 24 hours. That will seal up any cracks that might have been missed.

fattboyzz Hadn't heard of or even thought of the old egg preserver trick,they used that clear back in 1951 on flat head circle cars with cracked valve seats. Anything to get an engine to race with.

Enlighten us on the “old egg preserver trick”!

I love epoxy 👍😁

My dad would bring home some from work. Once I got the hang of it ,it was on 😁👍🤣

These days I use it in bodywork 👍

It's already been mentioned in this thread- - - - -sodium silicate, AKA "water glass". I used it on the rig I drove from middle Tennessee to Kansas City for Ed Pruss- - - -the 503 GMC that had a seep leak in a head gasket. Mix a heavy dose of water glass into water, warm the engine up, and let it cool down with a few pounds of pressure applied. When the mix cures especially if it's been exposed to combustion temperature, it cures into a glass-like substance with a melting point of 500+ degrees F. Antifreeze softens it, so it can only be used in warm weather. In the days before refrigeration, a water glass mixture was used to preserve eggs for several weeks at a time by dipping them into the solution and letting an airtight shell form.

https://www.farmhouseonboone.com/water-glassing-eggs

Jerry

It may have been mentioned, but never explained how it was used.

Knew a guy years ago who painted his John Deere H. Noticed a 1/4" by 6" area that wouldn't take paint.
The PO was a dentist. The block cracked. He filled the crack with amalgam. It didn't leak.

Phak1 In the olden days they had a sealant for chicken eggs that would make them keep better,it was a fairly thin liquid that would seal the egg shell. They also called it water glass. Enterprising mechanics learned to mix up a thicker concentration of that and use it to seal cracked blocks and valve seats. This was before permanent anti-freeze when they used methanol for anti-freeze. Prestone came in a 1 gallon rectanguler can that you used your curving oil stabber in the corner. There were many ways to administer crack repair,others will chime in .

Otto You could use a hand drill,especially in the truck,just don't break something off like the hard tap or the drill bit. The shop I worked in had a big box of those tapered plugs. You could use simple 1/8 th. pipe plugs made of cast iron too they would wedge the crack and cover more distance cause they were bigger.